Overview

Overview of iMac Pro (2017)

Features:

Display: 27-inch 5K Retina Display

Processor: 8-Core, 10-Core, 14-Core, 18-Core
Graphics: Radeon Pro Vega 56 graphics processor with 8GB of HBM2 memory
Configurable to Radeon Pro Vega 64 graphics processor with 16GB of HBM2 memory
Ports:
Nbase-T Ethernet
Four Thunderbolt 3 (USB-C) ports
Four USB 3 ports
SDXC card slot
T2 chip with new security features including:
Secure Enclave
Encrypted storage
Secure boot

For full technical specifications, refer to Apple Support Tech Specs: www.apple.com/imac-pro/specs.

Important Service Considerations:

The iMac Pro (2017) will not start up after a logic board and/or flash storage replacement until the Mac Configuration
Utility (MCU) is used. MCU is needed to serialize a logic board after a logic board replacement and to configure the
flash storage after new flash storage is installed. For instructions on how to use MCU, refer to article TP1625: How to
Use Mac Configuration Utility and service video SV369: System Configuration after a Logic Board or Flash Storage
Repair.
The flash storage devices are paired to the logic board and the data cannot be accessed or recovered when installed in
another logic board. Make sure the customer has a working backup of their data before removing or replacing the flash
storage devices. Refer to article HT201250: How to use Time Machine to back up or restore your Mac.

By default, security features keep the iMac Pro (2017) from being able to NetBoot, without disabling security features.
For instructions on how to boot to an external drive or another computer, refer to articles:
HT202796: How to select a different startup disk
HT208330: About Secure Boot
 HT208198: About Startup Security Utility
HT202770: Create a NetBoot, NetInstall, or NetRestore image
HT201462: How to use target disk mode to move files to another computer
Flash storage comes as a pair and must be replaced as a pair.
If the power supply bus bars are damaged or bent they must be replaced.

Fixtures and Special Tools:

Wireless card support tool (923-02218)

Adjustable torque driver 0.3–1.2 Nm (923-0735)
T8 security bit (923-0734)

Software updates:

iMac Pro (2017) ships with a model-specific version of macOS. Refer to article HT204319: Use the Mac operating system
that came with your Mac, or a compatible newer version to check that the system build is correct for this computer model.
Using Software Update, check for and apply the latest software and firmware updates.
Serial Number Location

The serial number for the following iMac models is located on the bottom of the stand.

Note: If the computer has a VESA mount, then the serial number is located on the underside of the VESA mount tongue.
The VESA mount for iMac Pro (2017) is customer installable.

iMac (21.5-inch, Late 2012)

iMac (27-inch, Late 2012)
iMac (21.5-inch, Early 2013)
iMac (21.5-inch, Late 2013)
iMac (27-inch, Late 2013)
iMac (21.5-inch, Mid 2014)
iMac (Retina 5K, 27-inch, Late 2014)
iMac (Retina 5K, 27-inch, Mid 2015)
iMac (21.5-inch, Late 2015)
iMac (Retina 4K, 21.5-inch, Late 2015)
iMac (Retina 5K, 27-inch, Late 2015)
iMac (21.5-inch, 2017)
iMac (Retina 4K, 21.5-inch, 2017)
iMac (Retina 5K, 27-inch, 2017)
iMac Pro (2017)

When replacing the stand, use a fine-tip black permanent marker to neatly write the serial number on the bottom of the new
stand.

Note: If replacing the VESA mount, then write the serial number on the underside of the replacement VESA mount tongue.
Input Devices

iMac Pro (2017) Input Devices

Space Gray Magic Trackpad 2

Space Gray Magic Mouse 2

Space Gray Magic Keyboard with Numeric Keypad

Features

Pairs via Bluetooth or via Lightning connector

Rechargeable embedded battery
On/off switch
Lightning connector

On/Off Switch
To turn on the Magic Trackpad 2 or Magic Keyboard, use the on/off switch (see 1 below) on the back of the device. This
switch is located on the bottom of the device for Magic Mouse 2. If green is visible inside the switch, then the device is turned
on. There is no indicator light. Note: When Magic Keyboards are turned on and paired with a system, the Caps Lock LED will
light up when Caps Lock is active.

Lightning Connector
The Magic Trackpad 2 and Magic Keyboard can be used wirelessly or wired, by plugging into the Lightning connector (see 2
below). The Magic Mouse 2 must be disconnected from Lightning Connector to operate.

Space Gray Magic Trackpad 2 (back)

Space Gray Magic Keyboard with numberic Keypad (back)

Space Gray Magic Mouse 2 (bottom)

Pair the device:

The device will automatically pair when plugged in and turned on. Plug the device into a USB port on the computer and
it will be detected.
The device can also be paired wirelessly. Turn the device on, find the name in the Bluetooth preference pane, and click
the name to pair.

Note: To check if the device is turned on, go to System Preferences > Bluetooth or click the Bluetooth icon in the menu bar.
If the device is both turned on and paired with the computer, then it will show in bold.

Charge the device:

Plug the device into a USB port on the computer using the Lightning cable.
Plug the device into a 5W, 10W, or 12W Apple USB Power Adapter using the Lightning cable.

Note: The computer will show an alert when the battery is low. The battery level information can also be found by selecting
the device in the Bluetooth menu in the menu bar.
General Troubleshooting

iMac Pro (2017) General Troubleshooting

Update Software and Firmware

Important: Make sure the iMac Pro (2017) is running the latest version of software and firmware. To check this, refer to
article HT201260: How to find the macOS version number on your Mac.

Troubleshooting Techniques

For more information, go to ATLAS and enter “troubleshooting” in the search field.

Hardware vs. Software

To isolate a hardware issue from a software issue, refer to article HT203161: Isolating issues in macOS.

To troubleshoot a software issue, refer to the following articles:

HT201516: How to troubleshoot a software issue

HT201861: About incompatible software on your Mac
HT204323: If a flashing question mark appears when you start your Mac
HT204904: How to reinstall macOS

Additional References:

HT204267: If your Mac won’t turn on

HT204156: About the screens you see when your Mac starts up
HT202179: About fans and fan noise in your Apple product
HT204463: Fans run at full speed after computer turns on
Power-On Self-Test (POST)

Intel-based Mac computers such as the iMac rely on a combination of tones and blinking LED lights to display Power-On
Self-Test (POST) error codes.

If the computer detects out-of-specification or no Random-Access Memory (RAM), the screen will remain black but the
computer will beep. This error condition may be due to physically damaged RAM, installing an incorrect type of RAM,
or not having RAM installed.
Some RAM may appear to pass POST, but still cannot be used by the operating system. In this case, the computer will
display a gray screen, sound three beeps and repeat beeps until computer is turned off.
The solution to both of these situations is to first reseat RAM and test computer again. If RAM fails POST again,
remove all installed RAM and test by installing one by one each RAM module that has been verified to work correctly
on another computer (“known-good” RAM, for example) or order new RAM.
A sequence of tones heard at startup or a no video symptom may also be fixed by temporarily removing/replacing the
backup battery.

For more information, refer to articles:

HT202768: About Mac startup tones

HT201702: About Mac Power On Self Test (POST) RAM error codes
HT201255: Startup key combinations for Mac
Quick Check Procedures

Resetting the System Management Controller (SMC)

The System Management Controller (SMC) is a chip on the logic board that controls all power functions. If the computer is
experiencing any power issue, such as not starting up, not displaying video, sleep issues, or fan noise issues, resetting SMC
may resolve it.

For more information and instructions to reset the SMC on different computer models, refer to article HT201295: How to
reset the System Management Controller (SMC) on your Mac.

Note for iMacs: If the power button is pressed while inserting the power cord, the iMac will enter a mode in which the fans
run at full speed. For more information, refer to article HT204463: Fans run at full speed after computer turns on.

Note for iMac Pro (2017): If the power button is pressed while inserting the power cord, the iMac will enter DFU mode and
will need to be restored.

Resetting Non-Volatile RAM (NVRAM)

NVRAM stores certain system and device settings in a location that macOS can access quickly. Exactly which settings are
stored in the computer’s NVRAM varies depending on the type of computer as well as the types of devices and drives
connected. To reset NVRAM:

1. Shut down the computer.

2. Locate the following keys on the keyboard: Command, Option (Alt), P, and R. You will need to hold these keys down
simultaneously in Step 4.
3. Press power button.
4. Immediately press and hold Command-Option-P-R keys.
Important: You must press this key combination before the gray screen appears.
5. Hold down keys until computer restarts, and you hear startup chime a second time.
Note: For MacBook Pro (Late 2016 and 2017) and MacBook (Retina, 12-inch, 2017), hold down keys for at least 20
seconds. There is no startup chime.
6. Release keys.

Note: After resetting NVRAM, you might need to reconfigure settings for speaker volume, screen resolution, startup disk
selection, and time zone information.

For more information, refer to article HT204063: How to Reset NVRAM on your Mac.

Starting Up in Safe Mode

Safe mode (sometimes called safe boot) is a way to start up a Mac so that it performs certain checks and prevents some
software from automatically loading or opening. These changes can help resolve or isolate certain issues on the startup disk.

Follow these steps to start up into safe mode:

1. Be sure the computer is shut down.

2. Press the power button.
3. Press and hold the Shift key.
Note: The Shift key should be pressed as soon as possible after the power button is pressed.
4. Release the Shift key when you see the Apple logo appear on the screen. After the Apple logo appears, it may take
longer than usual to reach the login screen. This is because the computer is performing a directory check as part of
safe mode.
5. To leave safe mode, restart the computer without pressing any keys during startup.

For more information, refer to article HT201262: Use safe mode to isolate issues with your Mac.
Recovering a Lost Firmware Password

Only Apple Retail Stores or Apple Authorized Service Providers can unlock the following Mac models when protected by a
firmware password:

iMac (Mid 2011 and later)

iMac Pro (2017)
MacBook (Retina, 12-inch, Early 2015 and later)
MacBook Air (Late 2010 and later)
MacBook Pro (Early 2011 and later)
Mac mini (Mid 2011 and later)
Mac Pro (Late 2013)

Refer to the technician instructions in article HT204455: How to set a firmware password on your Mac.
Diagnostic Software

Diagnostic Software for iMac Pro (2017)

Apple Service Toolkit 2 (AST 2)

AST 2 is a cloud-based diagnostic system to help technicians triage and verify repairs for Mac computers, starting with Mid
2014 models, except for MacBook Pro (Retina, Mid 2014). With AST 2, technicians are able to initiate diagnostics wirelessly
on a user’s device using Diagnostic Console (a web application on a Mac or iPad). Technicians are also able to view
diagnostic results in Diagnostic Console.

For more information, refer to the following articles:

OP476: Latest Apple Service Toolkit download links and documentation

TP1105: AST 2 for Mac Reference Guide - Table of Contents
TP1118: AST 2 for Mac Reference Guide - Table of Contents (Retail)
HT202731: How to use Apple Diagnostics on your Mac

Thermal Sensors

SMC General Description

Location Repair Suggestion
Name (Degrees C)
Excessive ambient temperature or logic board sensor
Logic board ambient Logic board bottom / front
TA0p is damaged or disconnected from SMC. Check logic
temperature side, near AC inlet
board connectors and fan operation.
Excessive backlight controller temperature or logic
Backlight controller Logic board top / back side,
TB0p board sensor is damaged or disconnected from SMC.
proximity temperature upper left edge
Check logic board connectors and fan operation.
Excessive CPU temperature or logic board sensor is
CPU proximity Logic board bottom / front
TC0p damaged or disconnected from SMC. Check logic
temperature side, middle center edge
board connectors and fan operation.
CPU core voltage Excessive CPU temperature or logic board sensor is
Logic board bottom / front
TC1p regulator proximity damaged or disconnected from SMC. Check logic
side, middle right edge
temperature, input side board connectors and fan operation.
CPU core voltage Excessive CPU temperature or logic board sensor is
Logic board bottom / front
TC2p regulator proximity damaged or disconnected from SMC. Check logic
side, middle right edge
temperature, output side board connectors and fan operation.
Excessive CPU temperature or logic board sensor is
CPU maximum package Logic board top / back side,
TCXc damaged or disconnected from SMC. Check logic
core PECI temperature on large CPU IC
board connectors and fan operation.
Excessive GPU temperature or logic board sensor is
Logic board top / back side,
TG0d GPU die 0 temperature damaged or disconnected from SMC. Check logic
on large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
Logic board top / back side,
TG1d GPU die 1 temperature damaged or disconnected from SMC. Check logic
on large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
Logic board top / back side,
TG2d GPU die 2 temperature damaged or disconnected from SMC. Check logic
on large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
Logic board top / back side,
TG3d GPU die 3 temperature damaged or disconnected from SMC. Check logic
on large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
GPU proximity 1 Logic board top / back side,
TG1p damaged or disconnected from SMC. Check logic
temperature near large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
GPU proximity 2 Logic board top / back side,
TG2p damaged or disconnected from SMC. Check logic
temperature near large GPU IC
board and I/O connectors and fan operation.
Excessive GPU temperature or logic board sensor is
GPU proximity 3 Logic board top / back side,
TG3p damaged or disconnected from SMC. Check logic
temperature near large GPU IC
board and I/O connectors and fan operation.
Excessive flash memory temperature or sensor is
Logic board top / back side,
TH0a/b/c/d SSD A (left) temperature damaged or disconnected from SMC. Check SSD
on SSD A
connectors and fan operation.
 Excessive flash memory temperature or sensor is
Logic board top / back side,
TH1a/b/c/d SSD B (right) temperature damaged or disconnected from SMC. Check SSD
on SSD B
connectors and fan operation.
Excessive Thunderbolt temperature or sensor is
Thunderbolt proximity Logic board bottom / front
TI0d damaged or disconnected from SMC. Check SSD
temperature side, near SSD A
connectors and fan operation.
Logic board top / back side, Excessive Thunderbolt temperature or sensor is
Thunderbolt die
TI1d near bottom-right DIMM damaged or disconnected from SMC. Check SSD
temperature
socket connectors and fan operation.
Logic board top / back side, Excessive Ethernet temperature or logic board sensor
10GB Ethernet proximity
TI0p near Ethernet RJ-45 is damaged or disconnected from SMC. Check logic
temperature
connector board connectors and fan operation.
Logic board top / back side, Excessive USB-C temperature or logic board sensor
USB-C 5V G3S voltage
TI1p near bottom-right DIMM is damaged or disconnected from SMC. Check logic
regulator temperature
socket board connectors and fan operation.
Logic board top / back side, Excessive Ethernet temperature or logic board sensor
TI2d Ethernet temperature near Ethernet RJ-45 is damaged or disconnected from SMC. Check logic
connector board connectors and fan operation.
Excessive display temperature or sensor is damaged
TL0p Display temperature LCD panel, back or disconnected from SMC. Check logic board and
display connectors and fan operation.
Excessive display temperature or sensor is damaged
TL1p TCON temperature LCD panel, back or disconnected from SMC. Check logic board and
display connectors and fan operation.
Logic board top / back side, Excessive memory temperature or sensor is damaged
DIMM proximity 0
TM0p near right side of lower or disconnected from SMC. Check memory
temperature
DIMM sockets connectors and fan operation.
Logic board top / back side, Excessive memory temperature or sensor is damaged
DIMM proximity 1
TM1p near left side of lower DIMM or disconnected from SMC. Check memory
temperature
sockets connectors and fan operation.
Logic board top / back side, Excessive memory temperature or sensor is damaged
DIMM proximity 2
TM2p near right side of upper or disconnected from SMC. Check memory
temperature
DIMM sockets connectors and fan operation.
Logic board top / back side, Excessive memory temperature or sensor is damaged
DIMM proximity 3
TM3p near left side of upper or disconnected from SMC. Check memory
temperature
DIMM sockets connectors and fan operation.
Logic board bottom / front Excessive logic board temperature or logic board
MLB proximity 0
Tm0p side, middle-right, near heat sensor is damaged or disconnected from SMC. Check
temperature
sink logic board connectors and fan operation.
Logic board top / back side, Excessive logic board temperature or logic board
MLB proximity 1
Tm1p upper-left, near power sensor is damaged or disconnected from SMC. Check
temperature
supply bus bars logic board connectors and fan operation.
Excessive logic board temperature or logic board
MLB proximity 2 Logic board bottom / front
Tm2p sensor is damaged or disconnected from SMC. Check
temperature side, lower-left, near SSD B
logic board connectors and fan operation.
Logic board bottom / front Excessive logic board temperature or logic board
MLB proximity 3
Tm3p side, lower-left, near large sensor is damaged or disconnected from SMC. Check
temperature
GPU IC logic board connectors and fan operation.
Excessive power supply temperature or sensor is
Power supply secondary
Tp2h Inside power supply damaged or disconnected from SMC. Check power
heat sink temperature
supply connectors and fan operation.
Logic board bottom / front Excessive logic board temperature or logic board
TPCD PCH Die temperature side, near SSD A, inside sensor is damaged or disconnected from SMC. Check
PCH IC logic board connectors and fan operation.

Electrical Sensor Table

SMC
Location General Description Units Repair Suggestion
Name
Logic Out of range CPU voltage was found or open signal to SMC.
VC0C CPU core load-side voltage Volts
board Check logic board connectors.
Logic Power supply 12V to CPU Out of range power supply voltage to CPU. Check power
VD2R Volts
board voltage supply connections to the logic board.
Logic Out of range GPU voltage was found or open signal to SMC.
VG0C GPU core low-side voltage Volts
board Check logic board connectors.
Logic Power supply 12V to GPU Out of range power supply voltage to GPU. Check power
VG2R Volts
board voltage supply connections to the logic board.
Logic Backlight controller 12V Out of range backlight current. Check connections from the
IB2R Amperes
board current display to the logic board.
Logic CPU core low side IMON Out of range CPU current was found or open signal to SMC.
IC0C Amperes
board current Check logic board connectors.
Out of range input/output current was found or open signal to
Logic
IC0I CPU I/O load-side current Amperes SMC. Check any connected input/output devices and logic
board
board connectors.
Logic CPU system agent Load- Out of range CPU current was found or open signal to SMC.
IC0S Amperes
board side IMON current Check logic board connectors.
Logic CPU core and system agent Out of range CPU current was found or open signal to SMC.
IC2R Amperes
board high-side current Check logic board connectors.
Logic Power supply 12V to CPU Out of range power supply current. Check power supply
ID2M Amperes
board current connections to the logic board.
Logic Power supply 12V to system Out of range power supply current. Check power supply
ID2R Amperes
board current connections to the logic board.
Logic GPU core low-side IMON Out of range GPU current was found or open signal to SMC.
IG0C Amperes
board current Check logic board connectors.
Logic GPU memory controller low- Out of range GPU current was found or open signal to SMC.
IG0M Amperes
board side current Check logic board connectors.
Logic GPU AUX 12V high-side Out of range GPU current was found or open signal to SMC.
IG2A Amperes
board current Check logic board connectors.
Logic Out of range GPU current was found or open signal to SMC.
IG2R GPU 12V high-side current Amperes
board Check logic board connectors.
Logic SSD A (left) 12V high-side Out of range SSD current was found or open signal to SMC.
IH02 Amperes
board current Check flash storage logic board connectors.
Logic SSD A (left) high-side Out of range SSD current was found or open signal to SMC.
IH0R Amperes
board current Check flash storage logic board connectors.
Logic SSD B (right) 12V high-side Out of range SSD current was found or open signal to SMC.
IH12 Amperes
board current Check flash storage logic board connectors.
Logic SSD B (right) high-side Out of range SSD current was found or open signal to SMC.
IH1R Amperes
board current Check flash storage logic board connectors.
Logic Memory SPD channels 0-1 Out of range memory current was found or open signal to SMC.
IM0P Amperes
board Load-side current Check memory connectors.
Logic Memory SPD channels 2-3 Out of range memory current was found or open signal to SMC.
IM2P Amperes
board Load-side current Check memory connectors.
Logic DIMM VDDQ all-channels Out of range memory current was found or open signal to SMC.
IMLR Amperes
board Load-side current Check memory connectors.
CPU memory controller
Logic Out of range CPU or memory current was found or open signal
IR01 channels 0-1 load-side Amperes
board to SMC. Check logic board and memory connectors.
current
CPU memory controller
Logic Out of range CPU or memory current was found or open signal
IR23 channels 2-3 load-side Amperes
board to SMC. Check logic board and memory connectors.
current
Out of range input/output current was found or open signal to
Logic USB-A 5V G3S voltage
IUAR Amperes SMC. Check any connected USB-A input/output devices and
board regulator current
logic board connectors.
Out of range input/output current was found or open signal to
Logic USB-C 5V G3S voltage
IUCR Amperes SMC. Check any connected USB-C input/output devices and
board regulator current
logic board connectors.
Testing the Panel Using the Display Extension Cable Kit

Testing the Panel Using the Display Extension Cable Kit for iMac (27-inch, Late 2012–2017) and iMac Pro (2017)

Use the display extension cable kit to:

Test the system and/or panel before securing the panel to the very high bond (VHB) adhesive strips.
Test the functionality of the panel’s Embedded DisplayPort (eDP) cable.

Warning: HIGH VOLTAGE. Use extreme caution when troubleshooting with the display panel removed. Avoid
touching the logic board or power supply while the computer is plugged in, the power supply retains a charge
whether or not the computer is on.

After unplugging the computer from the electrical outlet, wait two minutes before removing the display panel,
disconnecting modules, or substituting cables and components. This will allow the power supply and logic board
time to discharge.

Never remove or install any physical components while the computer is plugged in to an electrical outlet.
When plugged in, the power supply and logic board are energized, even when the computer is turned off.
Unplug the computer and allow sufficient time for the power supply and logic board to self-discharge before removing
the display panel.
Do NOT touch the logic board or the power supply while the computer is plugged in, or before sufficient time has
passed to discharge stored voltage to a safe level after being unplugged.

Refer to the following articles for more safety information:

TP833: iMac and Displays: Power Supply Cover Instructions

TP820: iMac (27-inch): Safety
TP1620: iMac Pro (2017): Power Supply Cover Instructions
TP1637: iMac Pro (2017): Safety

Tools

ESD wrist strap and mat

Black stick
Power supply protective covers, pack of two (923-0189)
LCD service support stand, iMac (923-0416)
Kit, display extension cable set (076-1431) for iMac (27-inch, Late 2012 and Late 2013)
 Kit, display extension cable set (076-00010) for iMac (Retina 5K, 27-inch, Late 2014–2017)
Kit, display extension cable set (076-00373) for iMac Pro (2017)
Painter’s tape

Note: The iMac (27-inch, Late 2013) display and extension cable kit are shown for the procedures. Follow the same setup
steps and procedures if testing the iMac (Retina 5K, 27-inch, Late 2014–2017) display or the iMac Pro (2017), but use the
correct kit for each.

iMac (Retina 5K, 27-inch, Late 2014–2017): 076-00010

iMac Pro (2017): 076-00373

Procedure #1: Testing the System With the Panel Off, Using Extension Cables

This procedure allows you to test the system with the panel off in order to ensure everything is functioning before securing
the panel with very high bond (VHB) adhesive strips.

First Steps

For iMac (27-inch, Late 2012–2017):

Display panel removal

Display panel - removing very high bond (VHB) strips

For iMac Pro (2017):

Display panel removal

Display panel - removing very high bond (VHB) strips

1. Place the LCD panel on the service support stand.

2. Orient the service support stand so the LCD backlight cable (#1) and eDP (#2) cable are facing you.
3. Locate the eDP extension cable in the kit.

4. Either end of the eDP substitution cable can connect to the logic board; the other end connects to the display.

Important: Each end of the eDP extension cable has a gold dot to indicate cable orientation. Orient the cable with the gold
dot side up when connecting the eDP extension cable to the logic board connector and the end of the LCD eDP cable.
Connecting cables upside down (with the brass connector facing up) will damage the logic board and/or the LCD panel.

Note: With proper care, cables will last for approximately 50 insertions. After 50 insertions, cable degradation may occur and
Apple recommends ordering a new Display Extension/Substitution Cable Kit (refer to the Tools section above).
 Correct Orientation (Gold Dot Side Up) Incorrect Orientation (Brass Side Up)

5. Flip the black tab up before connecting the eDP extension cable to the logic board connector.

Flip Tab Up Ready to Insert

6. With the iMac unplugged, connect the extension cable to the logic board connector. The cable should be aligned straight
on with the connector and never inserted at an angle. Important: Ensure that the black tab is attached to the locking lever on
the eDP cable. Attaching the locking lever without the black tab may cause damage to the logic board and/or the LCD panel.

Verify that each end of the cable has the gold dot side up.
Check that the connector is fully seated.
Flip the black tab down.
Press the locking lever to secure the cable to the logic board.
 Press Locking Lever to Secure
Flip Tab Down
Connector

7. Secure the logic board end of the eDP extension cable to the speaker with painter’s tape (see step 10).

8. Connect the other end of the eDP extension cable to the end of the dangling DisplayPort cable (#2).

9. Securely mate the cable connectors. Flip the black tab over and press the locking lever bar around the connector to
secure the cables.
10. The eDP extension cable will look like the image below when connected properly.

11. Next, locate the backlight extension (BLC) cable.

12. With the iMac unplugged, connect the backlight extension cable to the backlight connector on the logic board.
13. Connect the other end of the backlight extension cable to the dangling end of the LCD backlight cable (#1).

14. Securely mate the backlight extension cable with the panel’s backlight cable connector.
15. Locate the two power supply covers. With the iMac unplugged, position one horizontally over the power supply and one
vertically over the logic board and cables. Tape the power supply covers securely to the rear housing. Proper eDP and
backlight extension cable setup is shown below.

16. Attach the power cord to the iMac and start up the system to verify system functionality.

Procedure #2: Testing the Panel with the eDP Substitution Cable

This procedure tests an eDP cable to determine whether the issue is with the eDP cable. Remove the “suspect” eDP cable
from the circuit and replace it with the eDP substitution cable.

First Steps

For iMac (27-inch, Late 2012 – 2017):

 Display panel removal
Display panel - removing very high bond (VHB) strips

For iMac Pro (2017):

Display panel removal

Display panel - removing very high bond (VHB) strips

1. Place the LCD panel on the service support stand.

2. Orient the service support stand so the backlight cable (#1) and eDP (#2) cable are facing you.
3. Disconnect the eDP cable from the connector on the LCD panel. Use your fingernail to flip the locking lever bail. Pull the
cable out of the connector.

Unlock Locking Lever Bail Pull eDP Cable Out of Panel Connector

4. Locate the eDP substitution cable.

5. Either end of the eDP substitution cable can connect to the logic board; the other end connects to the display.

Important: Each end of the eDP substitution cable has a gold dot to indicate the cable orientation. Orient the cable with the
gold dot side up when connecting the eDP substitution cable to the logic board and to the connector on the LCD panel.
Connecting the cable upside down (with the brass connector facing you) will damage the logic board and/or the LCD panel.

Note: With proper care, cables will last for approximately 50 insertions. After 50 insertions, cable degradation may occur and
Apple recommends ordering a new Display Extension/Substitution Cable Kit (refer to the Tools section above).
 Incorrect Orientation
Correct Orientation
(Brass Side Up)
(Gold Dot Side Up)

6. With the iMac unplugged, connect one end of the eDP substitution cable to the connector on the logic board. The cable
should be aligned straight on with the connector and never inserted at an angle. The eDP substitution cable is shown
properly connected to the logic board. Important: Ensure that the black tab is attached to the locking lever on the eDP cable.
Attaching the locking lever without the black tab may cause damage to the logic board and/or the LCD panel.

Verify that each end of the cable has the gold dot side up.
Check that the connector is fully seated.
Flip the black tab down (#1).
Press the locking lever (#2) to secure the cable to the logic board.

Flip Tab Down, Press Locking Lever Correct Installation

7. Connect the other end of the eDP substitution cable to the eDP connector on the back of the LCD panel.
8. Flip the black tab up and press the locking lever bar to secure the cable to the connector on the panel.

9. Locate the backlight extension cable (BLC).

10. With the iMac unplugged, connect the backlight extension cable to the backlight connector on the logic board.
11. Connect the other end of the backlight extension cable to the dangling end of the LCD backlight cable (#1).

12. Securely mate the backlight extension cable with the panel’s backlight cable connector.
13. Locate the two power supply covers. With the iMac unplugged, position one horizontally over the power supply and one
vertically over the logic board and cables. Tape the power supply covers securely to the rear housing. The image below
shows the proper cable setup for the eDP substitution cable and backlight extension cable.

14. Attach the power cord to the iMac and start up the system to verify eDP cable functionality.
Interconnect Diagram

Interconnect Diagram for iMac Pro (2017)

Thermal sensors and cable connector locations are shown below.

Block Diagram

Block Diagram for iMac Pro (2017)

Refer to this diagram to see how modules are interrelated.

Functional Overview

Functional Overview for iMac Pro (2017)

For information on sensors and cable connections, refer to article TP1617: Interconnect Diagram.

Back of Logic Board

Refer to this diagram for symptoms related to the connectors on the back of the logic board.

1 = Coin cell battery

No power
No video

2 = DIMM memory (4)

Error beep tones on startup

Freeze or kernel panic
No boot

3 = Flash storage data and power (left connector A)

No flash storage seen in System Info

No boot from flash storage

4 = Flash storage data and power (right connector B)

No flash storage seen in System Info

No boot from flash storage

5 = Backlight fuse (FC600)

No LED backlight on internal display

6 = Display fuse (FC500)

No video but LED backlight on internal display

7 = Ethernet RJ-45
 No wired Ethernet connectivity
Wired Ethernet data transfer issues

8 = Thunderbolt 3 (USB-C) ports (4)

USB connectivity issues

USB power issues
No video to external display
No audio to external display speakers
Thunderbolt device not found
Thunderbolt controller not recognized
Thunderbolt driver issue
Thunderbolt power issues

9 = USB 3 ports (4)

USB connectivity issues

USB power issues

10 = SDXC Card Slot

No SD card seen in System Info

Data transfer issues

Front of Logic Board

Refer to this diagram for symptoms related to connectors on the front of the logic board.

11 = Dual fan assembly, left

System shuts down if fan is disconnected or blocked

System freezes or kernel panics
Noisy fan perception

12 = Display power (backlight control)

No LED backlight on internal display

Open backlight fuse F8100 on logic board

13 = Internal DisplayPort video

No video, blurred, or monochrome video on internal display

Open display fuse F4400 on logic board
14 = Diagnostic LEDs 1–5

1 = AC input voltage (trickle power present)

2 = Power supply DC output voltage
3 = Memory is functioning
4 = GPU is functioning
5 = Display panel is connected

15 = Diagnostic LED Button SL550

Press this button to view diagnostic LEDs

16 = RTC reset pads (SP1802 & SP1803)

Short across to reset Real Time Clock (RTC)

17 = Camera, camera LED, front microphones, and ambient light sensor (ALS)

No camera function
No LED when camera is on
No or distorted internal microphone input (with Internal Microphone selected in Sound Input Preferences)

18 = Dual assembly fan, right

System shuts down if fan is disconnected or blocked

System freezes or kernel panics
Noisy fan perception

19 = Rear microphone

No or distorted internal microphone input (with Internal Microphone selected in Sound Input Preferences)

20 = Right speaker

No sound from right speaker

Distorted sound from right speaker

21 = Wireless antenna connectors

Weak signal strength over Wi-Fi or Bluetooth

Cannot connect to Wi-Fi networks or Bluetooth peripherals
Slow Wi-Fi or Bluetooth connection speed

22 = Audio input/output

No external analog audio input

No external analog audio output
No headset controls or mic input

23 = Backup battery test points (SP8100 and SP8101)

Use to measure 3V DC backup battery coin voltage

24 = Left speaker

No sound from left speaker

Distorted sound from left speaker

25 = Power button

No power

26 = Power on signal and power supply temperature sensor

No power
Intermittent shutdown (if cable is pinched or damaged)
Fan runs at full speed
Bluetooth Device Connection Issues
Unlikely causes:
Battery, camera/microphone/ALS cable, fan, DisplayPort cable, display panel, left speaker, memory, power supply, rear
enclosure, right speaker, flash storage card, stand

Quick Check

Symptoms Quick Check

1. In System Preferences > Bluetooth, check that
Bluetooth is on.
2. Attempt to pair the computer with a known-good
Bluetooth keyboard, mouse, or trackpad.
3. Reset the Bluetooth device or delete the pairing (if
applicable).
4. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.
5. If the customer is using a USB 3 device, review article
HT201163: Using USB devices with your Mac to identify
possible interference with Wi-Fi and Bluetooth
communications if the device is positioned near their
antennas.
6. If the user’s computer pairs Bluetooth normally at your
service location, research potential sources of
interference in the user’s environment, such as
microwave ovens or cordless phones in the 2.4/5GHz
range. Refer to article HT201542: Potential sources of
Bluetooth cannot be enabled Wi-Fi and Bluetooth interference.
Bluetooth is not detected or available in System
7. Follow steps listed in HT204066: Use Bluetooth
Information
Diagnostics to help you isolate issues with wireless
Bluetooth can be turned on, but the computer is unable
devices.
to pair with a known-good Bluetooth device
Intermittent loss of communication with paired Bluetooth 8. Reset the NVRAM using the procedure for this computer
device in article HT204063: How to Reset NVRAM on your Mac.
Data transfer over Bluetooth times out or is too slow 9. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Note: Inform the user that computer failures due to accidental Controller (SMC) on your Mac to return computer to a
damage are not covered. If applicable, discuss out-of- known power-off state. Try to turn on from power-off
warranty repair options. state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
into DFU mode if you do.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Go to step 2.
Yes ${nodeText.yesSymptomCode}
Replace logic
Run Mac Resource Inspector (MRI) or check System board.
Information to verify that the wireless module is
recognized. Use Blank
Board
System Information: Serializer
1. (BBS) to set
Hardware > Bluetooth No the M36 MLB
computer’s
serial number.
Is Bluetooth service detected in MRI or System
Information? Verify that the
issue is
resolved.

Go to the
“External
Open System Preferences > Bluetooth. Remove all
Apple
paired devices. Pair the computer with a known-good
Bluetooth
Bluetooth device. Yes ${nodeText.yesSymptomCode}
Peripherals”
2.
troubleshooting
flow.
Does the computer pair with a known-good Bluetooth
device?
Go to step 3.
No ${nodeText.noSymptomCode}
Reinstall
macOS on the
user’s
computer.
Follow steps listed in HT208198: About Boot Security Refer to
Utility to enable starting up from an external storage HT201260:
device on the user’s computer. How to find the
macOS version
Start up computer using an up-to-date, bootable macOS number on
volume. See articles HT201314: About macOS your Mac to
Recovery and HT201260: How to find the macOS check that the ${nodeText.yesSymptomCode}
Yes
3. version number on your Mac. system build is
correct for this
Connect to a known-good Bluetooth device. Compare computer
Bluetooth performance and reliability to a known-good model. Check
computer of similar type and Bluetooth specification. for and apply
the latest
software and
Is the pairing issue resolved and is Bluetooth firmware
performance as expected? updates. Verify
resolution.

Go to step 4.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Turn off computer. Unplug computer from AC mains by Go to step 5.
Yes ${nodeText.yesSymptomCode}
disconnecting both ends of its power cord. Ensure
computer is completely disconnected from AC mains
before proceeding.

Remove display panel.

Locate the Bluetooth antenna, and inspect antenna’s

cable and connector for any damage.

Warning: HIGH VOLTAGE: The power supply

remains energized whenever the computer is
plugged in, whether or not the computer has been
turned on. Use extreme caution when
troubleshooting with the display panel removed.

Replace
4. Bluetooth
OTHER
No antenna. Verify X03
ELECTRIC
issue resolved.

Are antenna cable and connector in good condition?

Locate Bluetooth antenna port on logic board (top Go to step 6.
Yes ${nodeText.yesSymptomCode}
connector), and verify it is not damaged, loosened, or
unsoldered.
Replace logic
board.
Note: Be sure to follow all service guide procedures and
use the appropriate antenna removal tool and wireless
Use Blank
card support tool when working with antenna cables.
Board
Failure to do so may result in logic board damage.
Serializer
5. (BBS) to set
Disconnect the Bluetooth antenna cable (top connector)
No the M36 MLB
from the logic board.
computer’s
serial number.
Reseat antenna connector to logic board. Make sure
connection is secure and correctly aligned.
Verify that the
issue is
resolved.
Is Bluetooth antenna connector port in good condition
and securely seated?
Issue resolved
Connect an external display and try to pair with a by reseating
known-good Bluetooth device. Bluetooth
Yes ${nodeText.yesSymptomCode}
antenna. Verify
6.
resolution.
Did computer pair successfully with known-good
Bluetooth device? Go to step 7.
No ${nodeText.noSymptomCode}
Go to step 8.
The Bluetooth antenna is located on upper edge of the Yes ${nodeText.yesSymptomCode}
enclosure and is available as a standalone part.
Replace
7. Bluetooth
OTHER
No antenna. Verify X03
Do you have immediate access to a known-good ELECTRIC
issue resolved.
Bluetooth antenna?
 Check Result Action Code Commodity
Replace
Bluetooth
OTHER
Yes antenna. Verify X03
ELECTRIC
issue resolved.

Reinstall user's
Bluetooth
antenna.
Substitute known-good (upper) Bluetooth antenna. Replace logic
Connect an external display and try to pair with a board.
known-good Bluetooth device.
8. Use Blank
Board
Did computer pair successfully with known-good Serializer
No M36 MLB
Bluetooth device? (BBS) to set
the
computer’s
serial number.

Verify that the

issue is
resolved.

The issue is
Yes resolved. ${nodeText.yesSymptomCode}

Pair with a known-good Bluetooth device and verify that

the connection is sustained for several minutes.

Run AST 2 Full System Diagnostic (EFI & OS), if

available, to ensure no other issues remain. ESCALATION
9.
REQUIRED.
Verify that the issue is resolved. No X99
Contact ACS
for additional
Is the issue resolved? support or a
multiple-part
repair.
Ethernet Issues
Unlikely causes:
AirPort/Bluetooth antenna(s), battery, camera, camera/microphone/ALS cable or camera cable, CPU fan, DisplayPort cable,
hard disk drive (HDD), hard drive data or power or combo cable, display panel, left speaker, memory, power supply, rear
enclosure, right speaker, solid-state drive (SSD)/flash storage card, stand, wireless card

Quick Check

Symptoms Quick Check

1. Verify the network setup by accessing it directly via a
known-good computer’s Ethernet port.
2. Launch System Information. Verify that the computer’s
Ethernet port appears in the Network devices tree.
3. Test with known-good network hardware and an
Ethernet cable (Cat-5 or better is recommended for
100+ Mbps connections).
4. Using known-good network hardware and cable, start up
from a known-good, up-to-date macOS volume. Go to
Network Utility > Info and verify that Link Status is
“Active.”
5. Check network settings. If a known-good DHCP server
is available, set System Preferences > Network >
Ethernet to Using DHCP. Verify the IP address. (If it
begins with 169.x.x.x, the system was unable to get a
valid IP address.)
6. When started up from user’s OS, revert to default
network settings by creating a new location in System
Preferences > Network.
7. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure the system build is correct for this computer
model. Check for and apply the latest software and
No Ethernet device present. firmware updates.
Unable to access Ethernet network resources. 8. Run AST 1 or AST 2 Mac Resource Inspector (MRI) and
Ethernet device shows no connection. check results to verify that Ethernet hardware is
Ethernet device unable to get an IP address. detected.
Slow Ethernet network performance. 9. If AST 1 or AST 2 is not available, use System
Information to verify that Ethernet hardware is
Note: Inform user that computer failures due to accidental recognized.
damage are not covered. If applicable, discuss out-of-
warranty repair options. Warning: Be extremely careful when working inside the
computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Inspect the Ethernet port for dust, Go to step 2.
Yes ${nodeText.yesSymptomCode}
debris, damage, or bent pins. Use
compressed air to remove debris.
Plug in a known-good Ethernet
cable and make sure all pins
make physical contact with
1. connector.
Go to step 4.
No ${nodeText.noSymptomCode}

Are any Ethernet port pins

damaged or insufficiently
contacting the known-good
Ethernet connector?
Inspect logic board, Ethernet port, Go to step 3.
Yes ${nodeText.yesSymptomCode}
and enclosure for dents,
scratches, or other indications of
impact or abuse. Replace logic
2.
board. Verify issue
No M10 MLB
resolved.
Does accidental damage appear
to be cause of issue?
Inform user that computer failures Replace logic
due to accidental damage are not board. Verify issue
Yes M10 MLB
covered under any Apple resolved.
warranty, including AppleCare. If
applicable, discuss out-of-
3. Issue resolved.
warranty repair options.
Return computer to
No user using correct ${nodeText.noSymptomCode}
positioning.
Does user want to proceed with
out-of-warranty repair?
Ensure that the user’s computer Reinstall macOS on
is connected to the Internet using the user’s
a known-good Ethernet cable, computer. Refer to
and that Wi-Fi is turned off so that HT204319: Use the
all network traffic goes through Mac operating
built-in Ethernet. system that came
with your Mac, or a
Start up the computer using compatible newer
macOS Recovery or an up-to- version to check
date, bootable macOS volume. Yes ${nodeText.yesSymptomCode}
that the system
Hold down Command-R during build is correct for
startup to restart from the this computer
recovery partition. See articles model. Check for
HT201314: About macOS and apply the latest
Recovery and HT204319: Use software and
the Mac operating system that firmware updates.
4.
came with your Mac, or a Verify resolution.
compatible newer version.

Open Safari and attempt to

access a known-good external
web page such as
www.apple.com to verify Ethernet
connectivity. Look for the web
page to load, or for a timeout Go to step 5.
No ${nodeText.noSymptomCode}
indicating that the page did not
load.

Are Ethernet network resources

accessible starting from recovery
partition or a known-good OS?
 Check Result Action Code Commodity
Restart the user’s computer to Go to step 6.
Yes ${nodeText.yesSymptomCode}
the built-in macOS boot volume.

In System Preferences > Network

> Ethernet, verify that the link
status is Connected (green dot)
and that a valid IP address is
listed. Connect the computer to
an Ethernet network with a
known-good DHCP server. Make Replace logic
5.
sure static DHCP maps or board. Verify issue
No M10 MLB
filtering are not preventing resolved.
address allocation.

Note: DHCP allocation may not

be instantaneous, depending on
network. Retest.

Is Ethernet link status active?

No performance or
connectivity issues
detected. No repair
Go to System Preferences > necessary. The
Network > Ethernet and obtain problem may be the
router IP address. Use Network network
Utility to ping router IP address. environment. Refer
Yes user to article ${nodeText.yesSymptomCode}
Use a simple hub/switch
6. TS1317:
environment.
Troubleshooting a
cable modem, DSL,
Is Network Utility able to ping or LAN Internet
router IP address? connection.

Go to step 7.
No ${nodeText.noSymptomCode}
Replace logic
board. Verify issue
Yes M10 MLB
resolved.

No performance or
Perform network testing from connectivity issues
previous step, using same cable
detected. No repair
and network, but with a known- necessary. The
good computer. problem may be the
7. network
environment. Refer
Is network performance of user's No ${nodeText.noSymptomCode}
user to article
computer inferior to known-good TS1317:
computer?
Troubleshooting a
cable modem, DSL,
or LAN Internet
connection.
 Check Result Action Code Commodity
1. Connect Ethernet cable to a Yes Issue resolved.
${nodeText.yesSymptomCode}
known-good network with a
DHCP server.
2. In System Preferences >
Network > Ethernet, verify
link status is Connected
(green dot).
3. Configure TCP/IP settings
to Using DHCP and check
that a valid IP address is
obtained from server (not a
self-assigned one starting
with 169.x.x.x).
8. 4. Launch web browser and ESCALATION
verify that you can access No REQUIRED. M99
websites and download
files. Contact ACS for
additional support
Run ASD or AST 2 Full System or a multiple-part
Diagnostic (EFI & OS), if repair.
available, to ensure no other
issues remain.

Verify that the issue is resolved.

Is issue resolved?
Wi-Fi Connection Issues
Unlikely causes:
Battery, camera/microphone/ALS cable, DisplayPort cable, fan, flash storage card, display panel, left speaker, memory,
power supply, right speaker, stand

Quick Check

Symptoms Quick Check

 On user’s computer:

1. Refer to HT201260: How to find the macOS version

number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.
2. Using Ethernet network interface, connect to Internet,
then check for and apply latest software and firmware
updates.
3. Start up computer using recovery partition or an up-to-
date, bootable macOS volume, and attempt to connect
to a wireless network.
4. On a known-good computer, go to System Preferences
> Sharing and select Internet Sharing. Configure the
known-good computer to “Share your connection from”
> Ethernet and “To computers using” > Wi-Fi. Try to
connect user’s computer to the newly created wireless
network.
Using a known-good OS and base station, compare Wi
Fi throughput in Activity Monitor > Network to that of a
similar computer.
6. Refer to article HT202663: Check for Wi-Fi issues using
your Mac to familiarize yourself with the macOS
Wireless Diagnostic utility.
7. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
8. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Controller (SMC) on your Mac to return computer to a
known power-off state. Try to turn on from power-off
Wi-Fi cannot be enabled state. Do not hold in the power button when turning on
Wi-Fi is not detected or available in System Information the computer. You could inadvertently put the computer
Unable to find or connect to wireless networks into DFU mode if you do.
Slow or stalled data transfers
Intermittent connection dropouts If the issue cannot be reproduced on site, prompt the
user to check their Wi-Fi base station for the following:
Note: Inform the user that computer failures due to accidental
damage are not covered. If applicable, discuss out-of- 1. Check for base station firmware updates.
warranty repair options. 2. Check for nearby interference sources in the 2.4/5GHz
range such as microwave ovens and cordless phones.
See article HT201542: Potential sources of Wi-Fi and
Bluetooth interference.
3. Make sure base station is not using MAC address
filtering or has not created a hidden network.
4. Make sure base station is not set to low-power
transmission mode.
5. Make sure base station is not using an unsupported
connection and encryption protocol.
6. Check for Wi-Fi channel overlap (a nearby base station
using an adjacent channel).
7. Connect to a known-good test network.
8. Test in a different environment.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety
Deep Dive

Check Result Action Code

Go to step 2.
Run Mac Resource Inspector (MRI) or check System Yes ${nodeText.yesSymptomCode}
Information to verify that the wireless module is
Replace logic board.
recognized.
Use Blank Board Serializer
System Information:
1. (BBS) to set the computer’s
No serial number. M35
Network > Wi-Fi
Verify that the issue is
resolved.
Is Wi-Fi service detected in MRI or System Information?
Run Wireless Diagnostics by holding down the Option Go to step 3.
Yes ${nodeText.yesSymptomCode}
key, clicking the wireless icon in the menu bar, and then
choosing Open Wireless Diagnostics.

Wireless Diagnostics can also be found at:

2. /System/Library/CoreServices/Applications/Wireless
Go to step 4.
Diagnostics.app No ${nodeText.noSymptomCode}

Does the computer complete Wireless Diagnostics with

no issues?
Connect to a known-good wireless network and open Wi-Fi performance is within
Wireless Diagnostics > Window > Performance. Review specification. Verify that the
Yes ${nodeText.yesSymptomCode}
the quality graph to evaluate the signal quality of the issue is resolved.
wireless connection. Verify that the signal is good or
excellent, and that the transmission rate (Tx Rate) is
comparable to another known-good computer of similar
type and Wi-Fi specification. Where available, switch
between 2.4GHz and 5GHz networks to verify that the
signal quality is comparable to a known-good computer.
3.
Using a network with a high transmission rate, download
a large file from a known-good website or file server. Go to step 4.
No ${nodeText.noSymptomCode}
Compare network performance to another known-good
computer of similar type and Wi-Fi specification. Verify
throughput using Activity Monitor > Network.

Are the performance and throughput comparable

between the user’s computer and a known-good
computer?
Follow steps listed in HT208198: About Boot Security Go to step 5.
Yes ${nodeText.yesSymptomCode}
Utility to enable starting up from an external storage
device on the user’s computer.
Reinstall macOS on the user’s
Start up computer using an up-to-date, bootable macOS computer. Refer to HT201260:
volume. See articles HT201314: About macOS How to find the macOS version
Recovery and HT201260: How to find the macOS number on your Mac to check
4.
version number on your Mac. No that the system build is correct ${nodeText.noSymptomCode}
for this computer model. Check
Attempt to reproduce the Wi-Fi performance or for and apply the latest
connection issue. software and firmware
updates. Verify resolution.

Does issue persist with known-good OS?

Go to step 6.
Turn off Bluetooth to eliminate potential interference. Yes ${nodeText.yesSymptomCode}
Check for other interference such as microwave ovens
or cordless phones. See article HT201542: Potential Issue caused by interference.
Remove sources of
sources of Wi-Fi and Bluetooth interference. Change
5. interference, or use a different
base station channel.
No Wi-Fi channel or mode ${nodeText.noSymptomCode}
(2.4GHz or 5GHz). Verify issue
resolved.
Does the issue persist?
 Check Result Action Code
Turn off computer. Unplug computer from AC mains by Go to step 8.
Yes ${nodeText.yesSymptomCode}
disconnecting both ends of its power cord. Ensure
computer is completely disconnected from AC mains
before proceeding.

Remove display panel.

Locate the three Wi-Fi antennas and inspect each

antenna’s cable and connector for any damage.

6.
Go to step 7.
No ${nodeText.noSymptomCode}

Are Wi-Fi antenna cables and connectors in good

condition?
Replace affected Wi-Fi
Yes antenna. Verify issue resolved. X03

ESCALATION REQUIRED.

The antenna is part of the rear

Verify whether affected Wi-Fi antenna is available housing. Replace the rear
separately as a service part. housing. Verify issue resolved.
7.
No Inform user that failures due to X99
Is Wi-Fi antenna available as service part? accidental damage are not
covered by Apple’s one-year
limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.
 Check Result Action Code
Locate Wi-Fi antenna connector ports on logic board Go to step 9.
Yes ${nodeText.yesSymptomCode}
(bottom three connectors) and verify that they are not
damaged, loosened, or unsoldered.

Note: Be sure to follow all service guide procedures and

use the appropriate antenna removal tool and wireless
Replace logic board.
card support tool when working with antenna cables.
Failure to do so may result in logic board damage.
Use Blank Board Serializer
8. (BBS) to set the computer’s
Disconnect the Wi-Fi antenna cables (bottom three
No serial number. M35
connectors) from the logic board.
Verify that the issue is
Reseat antenna connectors to logic board. Make sure
resolved.
connections are secure and correctly aligned.

Are Wi-Fi antenna connector ports in good condition and

securely seated?
To verify Wi-Fi performance and reliability, start up Wi-Fi performance is within
computer using an up-to-date, bootable macOS, 10.8.4 specification. Verify issue
Yes ${nodeText.yesSymptomCode}
or later volume for access to Wireless Diagnostics resolved.
application. See article HT202663: Check for Wi-Fi
issues using your Mac to familiarize yourself with
wireless diagnostic utilities.

Connect to a known-good wireless network and open

Wireless Diagnostics > Window > Performance. Review
Quality and Rate graphs to evaluate signal of wireless
connection. Verify signal is good or excellent and
transmission rate (Tx Rate) is comparable to another
9. known-good computer of similar type and Wi-Fi
specification. Where available, switch between 2.4GHz
Go to step 10.
and 5GHz networks to verify signal quality is No ${nodeText.noSymptomCode}
comparable to a known-good computer. Using a
network with a high transmission rate, download a large
file from a known-good website or file server. Compare
network performance to another known-good computer
of similar type and Wi-Fi specification. Verify throughput
using Activity Monitor > Network.

Are performance and throughput comparable between

user's computer and a known-good computer?
Go to step 11.
Yes ${nodeText.yesSymptomCode}
To troubleshoot this issue completely, a set of known-
good Wi-Fi antennas is required. Replace logic board.

Note: Some Wi-Fi antennas are part of the rear housing Use Blank Board Serializer
10. and are not separately replaceable. (BBS) to set the computer’s
No serial number. M35

Do you have immediate access to a set of known-good Verify that the issue is
Wi-Fi antennas? resolved.

Go to step 12.
Yes ${nodeText.yesSymptomCode}
Substitute known-good Wi-Fi antenna. Connect external Reinstall user's Wi-Fi antenna.
display and retest, comparing performance and Replace logic board.
throughput of user's computer with known-good
computer. Repeat with other antennas. Use Blank Board Serializer
11.
(BBS) to set the computer’s
No M35
serial number.
Are performance and throughput comparable between
computers? Verify that the issue is
resolved.
 Check Result Action Code
Replace affected Wi-Fi
Yes antenna. Verify issue resolved. X03

ESCALATION REQUIRED.

The antenna is part of the rear

Verify whether affected Wi-Fi antenna is available housing. Replace the rear
separately as a service part. housing. Verify issue resolved.
12.
No Inform user that failures due to X99
Is Wi-Fi antenna available as service part? accidental damage are not
covered by Apple’s one-year
limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.

Connect to a known-good wireless network and retest Issue resolved.

Yes ${nodeText.yesSymptomCode}
data throughput, checking for adequate transfer
speeds.

Verify that wireless connection is sustained for several

minutes.
13.
Run ASD or AST 2 Full System Diagnostic (EFI & OS), ESCALATION REQUIRED.
No X99
if available, to ensure no other issues remain.
Contact ACS for additional
Verify that the issue is resolved. support or a multiple-part
repair.

Is issue resolved?
Backlight Issue / No Backlight
Unlikely causes:
Wireless antenna(s), battery, camera, camera/microphone/ALS cable, fan, left speaker, memory, power supply, rear
enclosure, right speaker, flash storage card, stand

Quick Check

Symptoms Quick Check

1. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.
2. Cover ambient light sensor to mimic a dark room and
adjust brightness to maximum setting using F2 key on
wired keyboard.
3. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
4. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Controller (SMC) on your Mac to return computer to a
Display not illuminated known power-off state. Try to turn on from power-off
Flickering, unstable, or non-uniform backlight state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
Poor backlight at some or all settings
Display backlight fails after warmup into DFU mode if you do.
Display backlight fails at certain brightness settings 5. Put the computer to sleep by pressing Control-Shift-
Unit appears to turn on and operate, but no image is Eject. Wake it by pressing any key.
seen on the display
Warning: Be extremely careful when working inside the
Note: Inform user that computer failures due to accidental computer with power applied and the system energized. Avoid
damage are not covered. If applicable, discuss out-of- touching the logic board or power supply while the computer
warranty repair options. is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive

Check Result Action Code Commodity

Connect a compatible external Go to step 2.
Yes ${nodeText.yesSymptomCode}
display. Check to see whether
the external display mirrors the
backlight issue or shows any Go to “Power But
1. video at all. Blank/No Video”
No troubleshooting ${nodeText.noSymptomCode}
flow.
Does external display show a
video signal of any kind?
Run AST 2 MRI. Review MRI Go to step 3.
Yes ${nodeText.yesSymptomCode}
results or System Information >
Graphics/Displays. Look for
Go to “Power But
information indicating internal
2. Blank/No Video”
display presence in results.
No troubleshooting ${nodeText.noSymptomCode}
flow.
Does MRI detect the display?
 Check Result Action Code Commodity
Shine bright (low-heat) flashlight Go to step 4.
Yes ${nodeText.yesSymptomCode}
onto front of display panel. With
computer turned on, verify
Go to “Power But
whether a faint image is visible.
3. Blank/No Video”
No troubleshooting ${nodeText.noSymptomCode}
flow.
Does display show a video signal
despite not being backlit?
Important: Ensure that user’s Replace the
computer is shut down, then display panel,
remove power cord and wait two which includes the
minutes for self discharge to Yes display power L09 LCD
occur. Remember to remove cable. Verify issue
power cord whenever resolved.
disconnecting modules or
substituting cables and
4.
components.

Inspect display power cable and

Go to step 5.
its connectors between logic No ${nodeText.noSymptomCode}
board and display panel.

Is the cable damaged?

Reseat display power cable Issue resolved by
between logic board and display reseating display
panel. Connect power cord to power cable.
Yes ${nodeText.yesSymptomCode}
computer, wait five seconds for Verify issue
SMC to become ready, then resolution.
press power button to start up
computer.

Warning: Be extremely careful

when working inside the
computer when power is applied
and system is energized. Avoid
5. touching the logic board or power
supply while the computer is
plugged in.
Go to step 6.
No ${nodeText.noSymptomCode}
For additional safety information
and tips, refer to article:

TP1637: iMac Pro (2017):

Safety

Is normal video including

backlight restored?
Important: Ensure that user’s Replace
computer is shut down, then DisplayPort cable.
INTERNAL
remove power cord and wait two Yes Verify issue X03
CABLE
minutes for self discharge to resolved.
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.
6.
Inspect DisplayPort cable for
misrouting. Disconnect
Go to step 7.
DisplayPort cable from logic No ${nodeText.noSymptomCode}
board. Inspect cable for pinching
and cable connector for damaged
or bent pins.

Is DisplayPort cable or its

connector damaged?
 Check Result Action Code Commodity
Replace logic
board.
Keep DisplayPort cable
Use Blank Board
disconnected from logic board.
Serializer (BBS)
Inspect DisplayPort connector on
to set the
the logic board for damaged or Yes M24 MLB
computer’s serial
7. bent pins.
number.

Verify that the

Is logic board cable connector
issue is resolved.
damaged?
Go to step 8.
No ${nodeText.noSymptomCode}
Test the logic board backlight Replace logic
fuse with a multimeter. For board.
information about using a
multimeter, see article HT3250: Use Blank Board
Diagnostics: Using a digital Serializer (BBS)
multimeter. to set the
Yes M25 MLB
computer’s serial
Refer to the service guide number.
Functional Overview for
information about locating Verify that the
backlight fuse. issue is resolved.

Locate backlight fuse on the logic

board. Be careful not to scratch
8. or knock nearby components off
the logic board when using the
multimeter probes.

Set the multimeter to measure

ohms ( ). Place the multimeter
Go to step 9.
probes on each side of the fuse No ${nodeText.noSymptomCode}
that is soldered to the logic
board. The multimeter should
measure between zero and one
ohm.

Does the multimeter show a

reading greater than 1 ?
Reseat the DisplayPort cable Issue resolved by
between display panel and logic reseating
board. DisplayPort cable.
Yes ${nodeText.yesSymptomCode}
Verify issue
Warning: Be extremely careful resolution.
when working inside the
computer when power is applied
9.
and system is energized. Avoid
touching the logic board or power
supply while the computer is Go to step 10.
No ${nodeText.noSymptomCode}
plugged in.

Is normal video restored?

 Check Result Action Code Commodity
To troubleshoot this issue Go to step 11.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
DisplayPort cable is required.
The iMac Display Extension
Cable Kit contains an embedded
DisplayPort (eDP) substitution
cable that can be used for
testing.
Replace
10. Refer to article TP981: iMac (27- DisplayPort cable.
INTERNAL
inch): Testing the Panel Using No Verify issue X03
CABLE
the Display Extension Cable Kit resolved.
for information about how to use
extension cables.

Do you have immediate access

to a known-good DisplayPort
cable?
Important: Ensure that user’s Replace
computer is shut down, then DisplayPort cable.
INTERNAL
remove the power cord and wait Yes Verify issue X03
CABLE
two minutes for self discharge to resolved.
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.
11.
Substitute a known-good
DisplayPort cable or use the Go to step 12.
No ${nodeText.noSymptomCode}
DisplayPort substitution cable
found in the extension cable kit in
place of suspect DisplayPort
cable.

Is normal video restored?

To troubleshoot this issue Go to step 13.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
12.
panel. Verify issue
No L09 LCD
resolved.
Do you have immediate access
to a known-good display panel?
Important: Ensure that user’s Replace display
computer is shut down, then panel. Verify issue
Yes L09 LCD
remove power cord and wait two resolved.
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
13. substituting cables and
components.
Go to step 14.
No ${nodeText.noSymptomCode}
Substitute a known-good display
panel.

Is normal video restored?

 Check Result Action Code Commodity
Go to step 15.
Yes ${nodeText.yesSymptomCode}
Replace logic
board.
To troubleshoot this issue
completely, a known-good logic
Use Blank Board
board is required.
Serializer (BBS)
14.
to set the
No M25 MLB
computer’s serial
Do you have immediate access
number.
to a known-good logic board?
Verify that the
issue is resolved.

Replace logic
board.

Use Blank Board

Serializer (BBS)
Important: Ensure that user’s to set the
computer is shut down, then Yes M25 MLB
computer’s serial
remove power cord and wait two number.
minutes for self discharge to
occur. Remember to remove Verify that the
power cord whenever issue is resolved.
disconnecting modules or
15. substituting cables and
components.

Substitute a known-good logic

board.
ESCALATION
No REQUIRED. M99
Is normal video restored?
Contact ACS for
additional support
or a multiple-part
repair.

Issue resolved.
Restart the computer and verify Yes ${nodeText.yesSymptomCode}
that the display backlight is fully
functional.

Run AST 2 Full System

Diagnostic (EFI & OS), if
16. available, to ensure no other ESCALATION
issues remain. No REQUIRED. ${nodeText.noSymptomCode}

Verify that the issue is resolved. Contact ACS for

additional support
or a multiple-part
Is the issue resolved? repair.
Display Anomalies
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, flash storage card/solid-state drive (SSD), hard disk
drive (HDD), hard drive data or power or combo cable, left speaker, power supply, rear enclosure, right speaker, stand, Wi-
Fi/Bluetooth antenna(s), wireless card.

Quick Check
 Symptoms Quick Check
References to the “Test Patterns Tool (TPT)” diagnostic
in this procedure are intended for all iMacs introduced
before 2014, that are supported by AST 1. For iMacs
introduced in 2014 and later, use the “Display
Anomalies” diagnostic that is supported by AST 2.

Note: Verify the issue after using the computer for a few
minutes to warm it, or by following steps in HT207571: Warm
a Mac for testing. Doing this may help identify intermittent
issues.

1. Use macOS Recovery to troubleshoot potential software

issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
2. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure the system build is correct for this computer
model. Check for and apply the latest software and
firmware updates, especially those that deal with display
or graphic issues. Remember that some external Apple
display adapters also contain firmware that may need
updating. For more information, refer to the following
articles:

HT201177: Get help with video issues on external

Distorted or blurred image displays connected to your Mac
Pixel anomalies HT201261: Intel-based iMac: Available updates
Vertical/horizontal lines
Unstable flickering 3. Verify that System Preferences > Accessibility > Display
Incorrect or missing colors > Display Contrast is set to Normal.
Nonuniform brightness at specific location 4. Check System Preferences > Displays > Color for
Vertical lines of nonuniform brightness repeating over possible use of a custom display profile. Ensure profile
the display is set to “iMac.”
Image persistence or image sticking on screen 5. Check the brightness setting.
Light leakage around the display 6. Clean the display and check for dust or debris.
7. Reset the NVRAM using the procedure for this computer
Note: Inform the user that computer failures due to accidental in article HT204063: How to Reset NVRAM on your Mac.
damage are not covered. If applicable, discuss out-of- 8. Reset the SMC using the procedure for this computer in
warranty repair options. article HT201295: How to reset the System
Management Controller (SMC) on your Mac.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Use the Display Anomalies test Go to “Unstable
suite in AST 2 or compare an Flickering”
image on the user’s display with Yes troubleshooting ${nodeText.yesSymptomCode}
the same image on an flow.
equivalent, known-good display.

Of the eight issues below,

determine if “unstable
flickering” best describes the
primary symptom:

Unstable flickering
1. Distorted/blurred image
Vertical/horizontal lines
Pixel anomalies Go to step 2.
No ${nodeText.noSymptomCode}
Nonuniform brightness
Incorrect or missing colors
Light leakage around the
display
Image persistence or
image sticking on screen

Is unstable flickering the primary

display issue?
Use the Display Anomalies test Go to step 3.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the seven issues below,

determine if “distorted/blurred
image” or “unstable flickering”
best describes the primary
symptom:

2. Distorted/blurred image
Go to step 15.
Vertical/horizontal lines No ${nodeText.noSymptomCode}
Pixel anomalies
Nonuniform brightness
Incorrect or missing colors
Light leakage around the
display
Image persistence or
image sticking on screen

Is a distorted or blurred image

the primary display issue?
Connect a compatible external Go to step 4.
Yes ${nodeText.yesSymptomCode}
display.
3.
Go to step 9.
No ${nodeText.noSymptomCode}
Does image on external display
appear distorted and/or blurred?
A distorted or blurred image may Go to step 9.
Before ${nodeText.yesSymptomCode}
be related to a failing memory
module. Watch closely during
startup sequence for exact point
at which issue starts to occur.
4.
Go to step 5.
After ${nodeText.noSymptomCode}
Does issue occur BEFORE or
AFTER Apple logo and spinning
gear appears?
 Check Result Action Code Commodity
Start the computer in Safe Go to step 9.
Yes ${nodeText.yesSymptomCode}
Mode.

To start up into Safe Mode,

follow steps listed in HT201262:
5. Use safe mode to isolate issues
Go to step 6.
with your Mac. No ${nodeText.noSymptomCode}

Does issue still occur in Safe

Mode?
Some models have RAM Go to step 7.
Yes ${nodeText.yesSymptomCode}
modules that are directly
connected to the MLB. You are
unable to remove the RAM on
6. these models.
Go to step 9.
No ${nodeText.noSymptomCode}

Are you able to remove RAM

modules?
Perform one-by-one Replace memory
replacement of user's memory module(s).
modules with known-good
memory, reassemble and Note: Only
retest. Depending on computer replace defective
model, this may simply require memory
Yes X06 MEMORY
removal of the rear door, or the module(s). There
removal of display panel and is no need to
logic board to access the replace memory
memory modules. in pairs. Verify
issue resolved.
Note: Be sure to always have at
least the minimum amount of
7.
memory installed to support the
computer and its OS. This may
mean replacing a memory
module with a known-good one
of larger capacity for testing. For
example, you may need to Go to step 8
No ${nodeText.noSymptomCode}
replace a 1 GB module with a
known-good 2 GB module to
support starting into macOS.

Does issue occur only with

specific memory module(s)?
Install a known-good memory Replace logic
module in one memory slot and board. Reinstall
retest. Repeat test with known- user’s memory.
Yes M04 MLB
good memory for each additional Verify issue
memory slot, one at a time. resolved.
8.

Does issue occur only with a Go to step 9.

No ${nodeText.noSymptomCode}
specific memory slot on logic
board?
 Check Result Action Code Commodity
Important: Ensure that user’s Go to step 10.
Yes ${nodeText.yesSymptomCode}
computer is shut down, then
remove power cord and wait two
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.

9. Remove display panel and

Go to step 12.
inspect DisplayPort cable for No ${nodeText.noSymptomCode}
misrouting. Disconnect
DisplayPort cable from logic
board. Inspect cable for pinching
and cable connector for
damaged or bent pins.

Is DisplayPort cable or its

connector damaged?
To troubleshoot this issue Go to step 11.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
DisplayPort cable is required.
The iMac Display Extension
Cable Kit contains an embedded
DisplayPort (eDP) substitution
cable that can be used for
testing.

Refer to article TP981: iMac (27-

inch): Testing the Panel Using Replace
10. DisplayPort cable.
the Display Extension Cable Kit INTERNAL
No Verify issue X03
or TP982: iMac (21.5-inch): CABLE
resolved.
Testing the Panel Using the
Display Extension Cable Kit for
information about how to use
extension cables.

Do you have immediate access

to a known-good DisplayPort
cable?
Important: Ensure that user's Replace
computer is shut down, then DisplayPort cable.
INTERNAL
remove power cord and wait two Yes Verify issue X03
CABLE
minutes for discharge to occur. resolved.
Remember to remove power
cord whenever disconnecting
modules or substituting cables
and components.
11.
Substitute a known-good eDP
cable or use the eDP Go to step 12.
No ${nodeText.noSymptomCode}
substitution cable found in the
extension cable kit in place of
suspect eDP cable.

Is normal video restored?

Keep DisplayPort cable Replace logic
disconnected from logic board. board. Verify
Yes M24 MLB
Inspect DisplayPort connector issue resolved.
on logic board for damaged or
12. bent pins.
Go to step 13.
No ${nodeText.noSymptomCode}
Is logic board cable connector
damaged?
 Check Result Action Code Commodity
To completely troubleshoot this Go to step 14.
Yes ${nodeText.yesSymptomCode}
issue, a known-good display
panel is required.
Replace display
13.
panel. Verify issue
No L04 LCD
resolved.
Do you have immediate access
to a known-good display panel?
Important: Ensure that user’s Replace display
computer is shut down, then panel. Verify issue
Yes L04 LCD
remove power cord and wait two resolved.
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.

Substitute a known-good display

panel to test logic board video
output.

Warning: Be extremely careful

when working inside the
computer with power applied Replace logic
14. and the system energized. Avoid
board. Reinstall
touching the logic board or user’s display
power supply while the computer No panel. Verify issue
M04 MLB
is plugged in. resolved.

For additional safety information

and tips, refer to articles:

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

Use the Display Anomalies test Go to step 16.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the six issues below,

determine if “vertical/horizontal
lines” best describes the
primary symptom:

15. Vertical/horizontal lines

Go to step 29.
Pixel anomalies No ${nodeText.noSymptomCode}
Nonuniform brightness
Incorrect or missing colors
Light leakage around the
display
Image persistence or
image sticking on screen

Are vertical or horizontal lines

the primary display issue?
 Check Result Action Code Commodity
Connect an external compatible Go to step 17.
Yes ${nodeText.yesSymptomCode}
display.

16.
Go to step 22.
Are vertical and/or horizontal No ${nodeText.noSymptomCode}
lines present on external
display?
Vertical and/or horizontal lines Go to step 22.
Before ${nodeText.yesSymptomCode}
may be related to a failing
memory module. Watch closely
during startup sequence for
exact point at which issue starts
17. to occur.
Go to step 18.
After ${nodeText.noSymptomCode}

Does issue occur BEFORE or

AFTER Apple logo and spinning
gear appears?
Start the computer in Safe Go to step 22.
Yes ${nodeText.yesSymptomCode}
Mode.

To start up into Safe Mode,

follow steps listed in HT201262:
18. Use safe mode to isolate issues
Go to step 19.
with your Mac. No ${nodeText.noSymptomCode}

Does issue still occur in Safe

Mode?
Some models have RAM Go to step 20.
Yes ${nodeText.yesSymptomCode}
modules that are directly
connected to the MLB. You are
unable to remove the RAM on
19. these models.
Go to step 22.
No ${nodeText.noSymptomCode}

Are you able to remove RAM

modules?
Perform one-by-one Replace memory
replacement of user's memory module(s).
modules with known-good
memory, reassemble and retest. Note: Only
Depending on computer model, replace defective
this may simply require removal memory
Yes X06 MEMORY
of the rear door, or the removal module(s). There
of display panel and logic board is no need to
to access the memory modules. replace memory
in pairs. Verify
Note: Be sure to always have at issue resolved.
least the minimum amount of
20. memory installed to support
computer and its OS. This may
mean replacing a memory
module with a known-good one
of larger capacity for testing. For
example, you may need to
Go to step 21.
replace a 1GB module with a No ${nodeText.noSymptomCode}
known-good 2GB module to
support starting into macOS.

Does issue occur only with

specific memory module(s)?
 Check Result Action Code Commodity
Install a known-good memory Replace logic
module in one memory slot and board. Reinstall
retest. Repeat test with known- user’s memory.
Yes M04 MLB
good memory for each additional Verify issue
memory slot, one at a time. resolved.
21.

Does issue occur only with a Go to step 22.

No ${nodeText.noSymptomCode}
specific memory slot on the logic
board?
Important: Ensure that user’s Go to step 23.
Yes ${nodeText.yesSymptomCode}
computer is shut down, then
remove power cord and wait two
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.

22. Remove display panel and

Go to step 25.
inspect DisplayPort cable for No ${nodeText.noSymptomCode}
misrouting. Disconnect
DisplayPort cable from logic
board. Inspect cable for pinching
and cable connector for
damaged or bent pins.

Is DisplayPort cable or its

connector damaged?
To troubleshoot this issue Go to step 24.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
DisplayPort cable is required.
The iMac Display Extension
Cable Kit contains an embedded
DisplayPort (eDP) substitution
cable that can be used for
testing.

Refer to article TP981: iMac (27-

inch): Testing the Panel Using Replace
23. DisplayPort cable.
the Display Extension Cable Kit INTERNAL
No Verify issue X03
or TP982: iMac (21.5-inch): CABLE
resolved.
Testing the Panel Using the
Display Extension Cable Kit for
information about how to use
extension cables.

Do you have immediate access

to a known-good DisplayPort
cable?
Important: Ensure that user’s Replace
computer is shut down, then DisplayPort cable.
INTERNAL
remove power cord and wait two Yes Verify issue X03
CABLE
minutes for discharge to occur. resolved.
Remember to remove power
cord whenever disconnecting
modules or substituting cables
and components.
24.
Substitute a known-good eDP
cable or use the eDP Go to step 25.
No ${nodeText.noSymptomCode}
substitution cable found in the
extension cable kit in place of
suspect eDP cable.

Is normal video restored?

 Check Result Action Code Commodity
Keep DisplayPort cable Replace logic
disconnected from logic board. board. Verify
Yes M24 MLB
Inspect DisplayPort connector issue resolved.
on logic board for damaged or
25. bent pins.
Go to step 26.
No ${nodeText.noSymptomCode}
Is logic board cable connector
damaged?
To troubleshoot this issue Go to step 27.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
26.
Go to step 28.
No ${nodeText.noSymptomCode}
Do you have immediate access
to a known-good display panel?
Important: Ensure that user’s Go to step 28.
Yes ${nodeText.yesSymptomCode}
computer is shut down, then
remove power cord and wait two
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.

Substitute a known-good display

panel to test logic board video
output.

Warning: Be extremely careful

when working inside the Replace logic
computer with power applied board. Reinstall
27. and the system is energized.
user’s display
Avoid touching the logic board or No panel. Verify issue
M04 MLB
power supply while the computer resolved.
is plugged in.

For additional safety information

and tips, refer to articles:

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

Replace display
Examine image on display and panel. Verify issue
Vertical L27 LCD
determine whether lines are resolved.
vertical or horizontal.
28.
Replace display
panel. Verify issue
Horizontal L26 LCD
Are lines vertical or horizontal? resolved.
 Check Result Action Code Commodity
Use the Display Anomalies test Go to step 30.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the five issues below,

determine if “pixel anomalies”
best describes the primary
symptom:
29.
Pixel anomalies Go to step 32.
No ${nodeText.noSymptomCode}
Nonuniform brightness
Incorrect or missing colors
Light leakage around the
display
Image persistence or
image sticking on screen

Are vertical or horizontal lines

the primary display issue?
Inspect display closely and Clean display
determine whether pixel panel if possible.
“anomalies” are actually dust or Yes Verify issue ${nodeText.yesSymptomCode}
debris on surface of display resolved.
panel.
30.

Go to step 31.
Are anomalies caused by dust, No ${nodeText.noSymptomCode}
debris, or other surface
contamination?
Refer to article HT202025: About Replace display
LCD display pixel anomalies for Yes panel. Verify issue
L20 LCD
Apple products released in 2010 resolved.
and later to determine whether
number of anomalies exceeds
specification. Determine whether Explain to user
that display is
31. number of bright or dark pixel
anomalies (or a combination of within
these) exceed specification. specifications. Do
No ${nodeText.noSymptomCode}
not replace
display panel.
Does the number of pixel Verify resolution.
anomalies exceed the specified
limit?
Use the Display Anomalies test Go to step 33.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the four issues below,

determine if “nonuniform
brightness” best describes the
primary symptom:
32.
Go to step 37.
Nonuniform brightness No ${nodeText.noSymptomCode}
Incorrect or missing colors
Light leakage around the
display
Image persistence or
image sticking on screen

Is nonuniform brightness the

primary display issue?
 Check Result Action Code Commodity
Go to step 34.
Determine whether variation in Yes ${nodeText.yesSymptomCode}
uniformity appears excessive
Display panel
when compared to a known-
seems to be
good similar computer.
within
33.
specifications. Do
No ${nodeText.noSymptomCode}
not replace
Does nonuniform brightness
display panel.
exceed that of a known-good
Verify resolution.
computer?
Important: Ensure that user’s Issue resolved by
computer is shut down, then reseating internal
remove power cord and wait two components.
Yes ${nodeText.yesSymptomCode}
minutes for self discharge to Verify issue
occur. Remember to remove resolution.
power cord whenever
disconnecting modules or
substituting cables and
components.

Remove display panel. Inspect

for mechanical interference from
screws or cables making contact
34.
with back of display panel.
Reseat components and cables.
Go to step 35.
No ${nodeText.noSymptomCode}
Carefully clean all surfaces of
any leftover tape or adhesive
residue where panel contacts
enclosure edges to ensure a
good seal and a flat mating
surface when display is reseated
to these surfaces.

Is normal video restored?

 Check Result Action Code Commodity
Important: Ensure that user’s Issue resolved by
computer is shut down, then reseating
remove power cord and wait two backlight cables.
Yes ${nodeText.yesSymptomCode}
minutes for self discharge to Verify issue
occur. Remember to remove resolution.
power cord whenever
disconnecting modules or
substituting cables and
components.

Inspect and reseat backlight

cable.

Connect power cord to

computer, wait five seconds for
SMC to become ready, then
press power button to start up
computer.

35. Warning: Be extremely careful

when working inside the
computer with power applied
and the system energized. Avoid No Go to step 36.
${nodeText.noSymptomCode}
touching the logic board or
power supply while the computer
is plugged in.

For additional safety information

and tips, refer to articles:

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

Important: Ensure that user’s Issue resolved by
computer is shut down, then reseating
remove power cord and wait two DisplayPort cable.
Yes ${nodeText.yesSymptomCode}
minutes for self discharge to Verify issue
occur. Remember to remove resolution.
power cord whenever
disconnecting modules or
substituting cables and
components.
36.
Reseat DisplayPort cable Replace display
connector securely to logic panel. Verify issue
No L21 LCD
board. Reconnect all internal resolved.
cables and reinstall display
panel. Retest.

Is normal video restored?

 Check Result Action Code Commodity
Use the Display Anomalies test Go to step 38.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the three issues below,

determine if “incorrect or
missing colors” best describes
the primary symptom:
37.
Go to step 46.
Incorrect or missing No ${nodeText.noSymptomCode}
colors
Light leakage around the
display
Image persistence or
image sticking on screen

Is incorrect or missing colors the

primary display issue?
Verify that display is listed in Go to step 39.
Yes ${nodeText.yesSymptomCode}
System Information > Hardware
> Graphics/Displays > Video
Card. This ensures that color
38. profile can be matched with
Go to step 40.
display panel. No ${nodeText.noSymptomCode}

Is display hardware detected?

Go to System Preferences > Go to step 40.
Yes ${nodeText.yesSymptomCode}
Displays > Color to make sure
“iMac” is selected under Issue resolved by
Display profile. Inspect display setting a valid
again for incorrect or missing display profile.
39. colors. User may have
No created an off- ${nodeText.noSymptomCode}
color calibration
Are colors still incorrect or setting. Verify
missing when display profile is resolution.
set to “iMac”?
Run Mac Resource Inspector Go to step 42.
Yes ${nodeText.yesSymptomCode}
(MRI) to check for display panel
presence.
40.
Go to step 41.
No ${nodeText.noSymptomCode}
Is display panel detected (green)
in MRI?
 Check Result Action Code Commodity
Important: Ensure that user’s Issue resolved by
computer is shut down, then reseating
remove power cord and wait two Yes DisplayPort cable. ${nodeText.yesSymptomCode}
minutes for self discharge to Verify resolution.
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.

Reseat DisplayPort cable

connector securely to logic
board and retest.

Connect power cord to

computer, wait five seconds for
SMC to become ready, then
press power button to start up
computer.
41. Warning: Be extremely careful
when working inside the
computer with power applied Go to step 42.
No ${nodeText.noSymptomCode}
and the system energized. Avoid
touching the logic board or
power supply while the computer
is plugged in.

For additional safety information

and tips refer to articles:

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

Launch the Test Pattern Tool Go to step 44.
Yes ${nodeText.yesSymptomCode}
(TPT) in AST or the Display
Anomalies test suite in AST 2 to
display the Solid Gray Light
display test pattern.
42.
Go to step 43.
Verify whether incorrect/missing No ${nodeText.noSymptomCode}
color issue affects entire screen.

Is entire screen affected?

Go to step 44.
Put computer side-by-side with a Yes ${nodeText.yesSymptomCode}
known-good equivalent iMac
Small variations in
display showing same Solid
color uniformity
Gray Light image.
43. are normal and do
No not warrant ${nodeText.noSymptomCode}
replacement of
Is issue noticeably worse on the
display.
user’s display?
To troubleshoot this issue Go to step 45.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
44.
panel. Verify issue
No L02 LCD
resolved.
Do you have immediate access
to a known-good display panel?
 Check Result Action Code Commodity
Important: Ensure that user’s Replace display
computer is shut down, then panel. Verify issue
Yes L02 LCD
remove power cord and wait two resolved.
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and Replace logic
45.
components. board. Reinstall
user’s display
No M04 MLB
Substitute a known-good display panel. Verify issue
panel to test logic board video resolved.
output.

Is normal video restored?

Use the Display Anomalies test Go to step 47.
Yes ${nodeText.yesSymptomCode}
suite in AST 2 or compare an
image on the user’s display with
the same image on an
equivalent, known-good display.

Of the two issues below,

determine if “light leakage
around the display” best
46. describes the primary symptom:
Go to step 50.
No ${nodeText.noSymptomCode}
Light leakage around the
display
Image persistence or
image sticking on screen

Is light leakage around display

edges the primary display issue?
Launch the Test Pattern Tool Go to step 48.
Yes ${nodeText.yesSymptomCode}
(TPT) in AST or the Display
Anomalies test suite in AST 2 to
display the All Black display test
pattern.

It is very important that you

verify this issue using ONLY an
all black display test pattern with
no other images present such as Explain to user
icons, dock, and so on. that display is
within
47.
Adjust display position and specifications. Do
No ${nodeText.noSymptomCode}
brightness to normal settings. not replace
display panel.
Dim lights so you can more Verify resolution.
clearly see any light leakage
around edges of the display
panel.

Is any noticeable light leakage

present around edges of the
display?
 Check Result Action Code Commodity
Important: Ensure that user’s Replace chin
computer is shut down, then strap. Reinstall
remove power cord and wait two user’s display
Yes X13 PIECE PART
minutes for self discharge to panel. Verify issue
occur. Remember to remove resolved.
power cord whenever
disconnecting modules or
substituting cables and
components.

Carefully disconnect and remove

display panel.

Carefully clean all surfaces of

any leftover tape or adhesive
residue where panel contacts
enclosure edges to ensure a
48. good seal and a flat mating
surface when display is reseated
to these surfaces.
Go to step 49.
No ${nodeText.noSymptomCode}
Remove and closely inspect chin
strap for any damage, bowing,
or bending.

Verify that all cushioned pads

are securely installed on each
end of the chin strap and are not
damaged, torn, out of place, or
missing. These pads are part of
the chin strap.

Does chin strap appear

damaged, bent, or bowed?
 Check Result Action Code Commodity
Recheck that previous Replace display
disassembly was performed panel. Verify issue
Yes L28 LCD
properly using proper tools and resolved.
techniques and not by simply
pulling display off. Incorrect
removal technique can damage
or bow chin strap, causing light
leakage in lower display area.

Reinstall chin strap, being very

careful to not damage, bow, or
otherwise bend chin strap during
installation.

Reapply new foam tape gaskets

for all four display sides, being
very careful to apply the tape
smoothly around entire edge.

Reinstall display panel, being

careful when seating edges of Issue resolved by
49.
display against foam-backed reseating display
tape around edges to ensure a and chin strap.
No ${nodeText.noSymptomCode}
smooth, complete seal around Verify issue
entire perimeter. resolution.

Connect power cord to

computer, wait five seconds for
SMC to become ready, then
press power button to start up
computer.

Retest using the Test Pattern

Tool (TPT) in AST or the Display
Anomalies test suite in AST 2 to
display the All Black display test
pattern.

Is any noticeable light leakage

still present around edges of
display?
A display might show a Replace display
temporary faint remnant of a panel. Verify issue
Yes L25 LCD
previous image even after a new resolved.
image replaces it. Follow
instructions using procedure
listed for this computer in article
TP949: Image Persistence Test The display is
50.
to determine if display fails or within
passes the Image Persistence specification. Do
No ${nodeText.noSymptomCode}
Test. not replace
display panel.

Does the display fail the Image

Persistence Test?
Issue resolved.
Yes ${nodeText.yesSymptomCode}
Verify that display issue or
anomaly has been resolved.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
available, to ensure no other ESCALATION
51.
issues remain. REQUIRED.
No M99
Verify that the issue is resolved. Contact ACS for
additional support
or a multiple-part
Is issue resolved? repair.
Power But Blank/No Video
Unlikely causes:
Battery, camera/microphone/ALS cable, CPU fan, flash storage card, left speaker, power supply, rear enclosure, right
speaker, stand, Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

1. Adjust settings to increase screen brightness.
2. In the event that there is an iBridge / macOS version
mismatch in the user’s computer, iBridge firmware will
update automatically while the computer is connected to
the Internet. During this process the computer’s display
can remain completely black for some period of time (at
least 30 seconds). If the computer is turned off or
disconnected from the Internet during this process under
the assumption that something went wrong, the black
screen will occur again until the iBridge update has
completed. To resolve this issue, plug in the computer,
attempt to turn it on, then wait at least one minute to
provide an opportunity for any updates to complete if
needed. Once completed, the computer should display
video once again. For more information, see OP1935:
iMac Pro (2017) Service Readiness Guide.
3. After logic board replacement, if the computer turns on
but displays only a black screen and does not start up,
this could mean that the replacement logic board has
not yet been configured for use. For complete
instructions to configure a replacement logic board, refer
to TP1625: How to use the Mac Configuration Utility.
4. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
5. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Power available, but no video visible on display
Controller (SMC) on your Mac to return computer to a
Fan spinning sounds are audible
known power-off state. Try to turn on from power-off
Caps Lock key LED illuminates when pressed
state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
Note: Inform user that computer failures due to accidental
into DFU mode if you do.
damage are not covered. If applicable, discuss out-of-
6. Disconnect all peripherals.
warranty repair options
7. Use macOS Recovery to troubleshoot potential software
issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
8. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety
Deep Dive

Check Result Action Code Commodity

Reset the NVRAM using the Go to step 3.
Yes ${nodeText.yesSymptomCode}
procedure for this computer in
article HT204063: How to Reset
NVRAM on your Mac.

Press the power button to start

up the computer.
1.
Look and listen for any evidence Go to step 2.
No ${nodeText.noSymptomCode}
that the computer is starting up.
Be aware that this iMac model
does not emit a startup sound.

Is there any evidence that the

computer is starting up?
Connect a known-good Apple Go to “Will Not
wired keyboard and Apple wired Start Up”
mouse to user's computer. Yes troubleshooting ${nodeText.yesSymptomCode}
flow.
Hold down Command-R during
startup to restart from the
recovery partition.
2.
Check whether computer has a
memory error (a series of beep Go to step 3.
No ${nodeText.noSymptomCode}
tones during startup).

Does computer make error tones

during startup?
Determine whether issue is no Go to “Backlight
backlight or no image: Issue / No
No Backlight”
${nodeText.yesSymptomCode}
Image with no backlight Backlight troubleshooting
can be seen by shining a flow.
flashlight onto the built-in
display during or after
startup.
3.
No image can be identified
by a blank display with or
without backlight or a solid Go to step 4.
No Image ${nodeText.noSymptomCode}
color on the built-in display.

Is the issue no backlight or no

image?
Connect a known-good external Go to step 5.
Yes ${nodeText.yesSymptomCode}
display and press power button.
Hold down Command-R during
startup to restart from the
recovery partition. Toggle video
mirroring (Command-F1) to view
main screen startup screen on
4.
external display. Verify that video Go to step 11.
No ${nodeText.noSymptomCode}
is correct when viewed on
external display.

Is correct image visible on

external display?
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 11.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding and
allow the power supply and logic
board to discharge.

Use one of the methods below to

determine whether the user's
computer recognizes its built-in
display panel.

METHOD 1:
Review MRI results or System
Information > Graphics/Displays.
Look for information indicating
internal display presence in
results.

METHOD 2:
Follow service guide procedures
to remove the display to gain
access to view diagnostic LEDs
on the logic board. Use display
extension cables and the display
service stand to keep the display
5. connected while removed.
Go to step 6.
No ${nodeText.noSymptomCode}
Connect AC power cord to the
computer and plug into mains.
Locate diagnostic LEDs on logic
board. Press the power button to
start up the computer. Press the
diagnostic button (near
diagnostic LEDs on logic board)
to activate and view LEDs.
During startup, the computer
should communicate with video
controller and light diagnostic
LED #5 to indicate an active
display.

Warning: HIGH VOLTAGE: The

power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Is built-in display panel

detected?
Inspect eDP cable and Go to step 7.
Yes ${nodeText.yesSymptomCode}
connectors for damage. Also
inspect connectors on display
panel and logic board.
6.
Go to step 8.
No ${nodeText.noSymptomCode}
Did you find any damaged
components?
 Check Result Action Code Commodity
Replace
embedded
DisplayPort (eDP) INTERNAL
Yes X03
cable. Verify issue CABLE
resolved.

Damage to multiple parts

requires an escalation to ACS for
approval for repair.
7.

Is damage limited to eDP cable ESCALATION

only? No REQUIRED. ${nodeText.noSymptomCode}
Contact ACS for
additional support
or a multiple-part
repair.

Test the logic board display Replace logic

power fuse with a multimeter. board. Verify issue
Yes M03 MLB
For information about using a resolved.
multimeter, see article HT3250:
Diagnostics: Using a digital
multimeter.

Refer to the service guide

Functional Overview for
information about locating
display fuse.

Locate display fuse on the logic

board. Be careful not to scratch
8. or knock nearby components off
the logic board when using the
Go to step 9.
multimeter probes. No ${nodeText.noSymptomCode}

Set the multimeter to measure

ohms ( ). Place the multimeter
probes on each side of the fuse
that is soldered to the logic
board. The multimeter should
measure between zero and one
ohm.

Does the multimeter show a

reading greater than 1 ?
To troubleshoot this issue Go to step 10.
Yes ${nodeText.yesSymptomCode}
completely, a known-good eDP
cable is required. The iMac
Display Extension Cable Kit
contains an eDP substitution
cable that can be used for
testing.
Replace
embedded
9. Refer to article TP981: iMac (27-
DisplayPort (eDP) INTERNAL
inch): Testing the Panel Using No X03
cable. Verify issue CABLE
the Display Extension Cable Kit
resolved.
for information about how to use
extension cables.

Do you have immediate access

to a known-good eDP cable?
 Check Result Action Code Commodity
Important: Ensure that user's Replace
computer is shut down, then embedded
remove power cord and wait two With DisplayPort (eDP) INTERNAL
X03
minutes for discharge to occur. Backlight cable. Verify issue CABLE
Remember to remove power resolved.
cord whenever disconnecting
modules or substituting cables
and components.

Substitute a known-good eDP

cable or use the eDP substitution
10. cable found in the extension
cable kit in place of suspect eDP Replace the
cable. display panel.
No
Verify issue L03 LCD
Backlight
If any known-good cables are resolved.
still installed from previous steps,
continue using known-good
cables to help find faulty module.

Does display present video with

or without backlight?
Turn off computer. Unplug Go to step 12.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding and
allow the power supply and logic
board to discharge.

Remove display panel.

Locate diagnostic LEDs on logic

board. Connect AC power cord
and press power button. Press
the diagnostic button (near
diagnostic LEDs on logic board)
to activate and view LEDs. Go to “No Power”
11.
Diagnostic LEDs #1 and #2 troubleshooting
No ${nodeText.noSymptomCode}
should turn on. This indicates flow.
power to computer.

Warning: HIGH VOLTAGE: The

power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Are diagnostic LEDs #1 and #2

on?
 Check Result Action Code Commodity
Disconnect embedded Replace display
DisplayPort (eDP) cable from panel. Verify issue
Yes L03 LCD
logic board. Connect a known- resolved.
good external display and press
power button. Hold down
Replace logic
Command-R during startup to
board.
restart from recovery partition.
Toggle video mirroring
Use Blank Board
12. (Command-F1) to view main
Serializer (BBS)
screen startup screen on
to set the
external display. Verify that video No M03 MLB
computer’s serial
is correct when viewed on
number.
external display.
Verify that the
issue is resolved.
Is correct image visible on
external display?
Issue resolved.
Yes ${nodeText.yesSymptomCode}
Restart the computer and verify
that the video is fully functional.

Run AST 2 Full System

Diagnostic (EFI & OS), if
available, to ensure no other ESCALATION
13.
issues remain. REQUIRED.
No ${nodeText.noSymptomCode}
Verify that the issue is resolved. Contact ACS for
additional support
or a multiple-part
Is the issue resolved? repair.
Unstable Flickering
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, hard disk drive (HDD), hard drive data or power or
combo cable, left speaker, memory, power supply, rear enclosure, right speaker, solid-state drive (SSD)/flash storage card,
stand, Wi-Fi/Bluetooth antennas, wireless card

Quick Check

Symptoms Quick Check

Note: Verify the issue after using the computer for a few
minutes to warm it, or by following steps in HT207571: Warm
a Mac for testing. Doing this may help identify intermittent
issues.

1. Use macOS Recovery to troubleshoot potential software

issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
2. Check the brightness setting.
3. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure the system build is correct for this computer
model. Check for and apply the latest software and
firmware updates, especially those that deal with display
or graphic issues. Remember that some external Apple
display adapters also contain firmware that may need
updating. For more information, refer to the following
articles:

HT201177: Get help with video issues on external

displays connected to your Mac
HT201261: Intel-based iMac: Available updates
Flickering video image
Flickering backlight 4. Clean display and check for dust or debris.
Dock and/or menu bar position not stable 5. Reset the NVRAM using the procedure for this computer
Display intermittently flashes on/off in article HT204063: How to Reset NVRAM on your Mac.
Unstable image 6. Reset the SMC using the procedure listed for this
computer in article HT201295: Reset the System
Note: Inform user that computer failures due to accidental Management Controller (SMC) on your Mac.
damage are not covered. If applicable, discuss out-of-
warranty repair options. Warning: Be extremely careful when working inside the
computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety
Deep Dive

Check Result Action Code Commodity

Adjust built-in display brightness Go to step 2.
Backlight ${nodeText.yesSymptomCode}
setting to low backlight level, just
above off.

Verify whether user issue is due

to backlight flickering or to an
unstable or flickering video image
on display.

You may need to shine a bright

(low heat) flashlight onto front of
display panel with computer
turned ON to verify whether a
faint video image is occasionally
1.
visible through the flickering. Go to step 8.
Video ${nodeText.noSymptomCode}
Note: If video is present but
backlight never turns on, exit this
procedure and go to the “
Backlight Issue / No Backlight
” troubleshooting flow instead.
Use this procedure only for
flickering backlight or video
image.

Which is flickering, backlight or

video?
Important: Ensure that user's Replace display
computer is shut down, then panel, which
remove power cord and wait two includes display
minutes for self discharge to Yes power cable. L06 LCD
occur. Remember to remove Verify issue
power cord whenever resolved.
disconnecting modules or
substituting cables and
2.
components.

Inspect display power cable and

Go to step 3.
its connectors between logic No ${nodeText.noSymptomCode}
board and display panel.

Is display power cable damaged?

 Check Result Action Code Commodity
Reseat display power cable Issue resolved by
between logic board and display reseating display
panel. Connect power cord to power cable.
Yes ${nodeText.yesSymptomCode}
computer, wait five seconds for Verify issue
SMC to become ready, then resolution.
press power button to start up
computer.

Warning: Be extremely careful

when working inside the
computer while power is
connected and system is
energized. Avoid touching the
logic board or power supply while
3. the computer is plugged in.

For additional safety information Go to step 4.

and tips, refer to articles: No ${nodeText.noSymptomCode}

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

To troubleshoot this issue Go to step 5.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
4.
panel. Verify
No L06 LCD
issue resolved.
Do you have immediate access
to a known-good display panel?
Important: Ensure that user's Replace display
computer is shut down, then panel. Verify
Yes L06 LCD
remove power cord and wait two issue resolved.
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
5. substituting cables and
components.
Go to step 6.
No ${nodeText.noSymptomCode}
Substitute a known-good display
panel.

Is normal video restored?

To troubleshoot this issue Go to step 7.
Yes ${nodeText.yesSymptomCode}
completely, a known-good power
supply is required.
Replace power
6.
supply. Verify POWER
No P99
issue resolved. SUPPLY
Do you have immediate access
to a known-good power supply?
 Check Result Action Code Commodity
Replace power
Important: Ensure that user's supply. Verify POWER
computer is shut down, then Yes P99
issue resolved. SUPPLY
remove power cord and wait two
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
7. substituting cables and
components. ESCALATION
No REQUIRED. M99
Substitute a known-good power
supply. Contact ACS for
additional support
or a multiple-part
Is normal video restored? repair.

Turn off computer. Unplug Replace

computer from AC mains by DisplayPort
INTERNAL
disconnecting both ends of its Yes cable. Verify X03
CABLE
power cord. Ensure computer is issue resolved.
completely disconnected from
AC mains before proceeding.

Remove display panel and

inspect DisplayPort cable for
8.
misrouting. Disconnect
DisplayPort cable from logic
Go to step 9.
board. Inspect cable for pinching No ${nodeText.noSymptomCode}
and cable connector for
damaged or bent pins.

Is DisplayPort cable or its

connector damaged?
Keep DisplayPort cable Replace logic
disconnected from logic board. board. Verify
Yes M24 MLB
Inspect DisplayPort connector on issue resolved.
logic board for damaged or bent
9. pins.
Go to step 10.
No ${nodeText.noSymptomCode}
Is logic board cable connector
damaged?
 Check Result Action Code Commodity
Reseat DisplayPort cable Issue resolved by
between LCD panel and logic reseating
board. Connect power cord to DisplayPort
Yes ${nodeText.yesSymptomCode}
computer, wait five seconds for cable. Verify
SMC to become ready, then issue resolution.
press power button to start up
computer.

Warning: Be extremely careful

when working inside the
computer while power is
connected and system is
energized. Avoid touching the
logic board or power supply while
10. the computer is plugged in.

For additional safety information Go to step 11.

and tips, refer to articles: No ${nodeText.noSymptomCode}

TP820: iMac (27-inch):

Safety
TP914: iMac (21.5-inch):
Safety
TP1637: iMac Pro (2017):
Safety

Is normal video restored?

To troubleshoot this issue Go to step 12.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
DisplayPort cable is required.
The iMac Display Extension
Cable Kit contains an embedded
DisplayPort (eDP) substitution
cable that can be used for
testing.

Refer to article TP981: iMac (27-

inch): Testing the Panel Using Replace
11. DisplayPort
the Display Extension Cable Kit INTERNAL
No cable. Verify X03
or TP982: iMac (21.5-inch): CABLE
issue resolved.
Testing the Panel Using the
Display Extension Cable Kit for
information about how to use
extension cables.

Do you have immediate access

to a known-good DisplayPort
cable?
Important: Ensure that user's Replace
computer is shut down, then DisplayPort
INTERNAL
remove power cord and wait two Yes cable. Verify X03
CABLE
minutes for self discharge to issue resolved.
occur. Remember to remove
power cord whenever
disconnecting modules or
substituting cables and
components.
12.
Substitute a known-good eDP
Go to step 13.
cable or use the eDP substitution No ${nodeText.noSymptomCode}
cable found in the extension
cable kit in place of suspect eDP
cable.

Is normal video restored?

 Check Result Action Code Commodity
To troubleshoot this issue Go to step 14.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
13.
panel. Verify
No L06 LCD
issue resolved.
Do you have immediate access
to a known-good display panel?
Important: Ensure that user's Replace display
computer is shut down, then panel. Verify
Yes L06 LCD
remove power cord and wait two issue resolved.
minutes for self discharge to
occur. Remember to remove
power cord whenever
disconnecting modules or
Replace logic
14. substituting cables and
board. Reinstall
components.
user’s display
No M29 MLB
panel. Verify
Substitute a known-good display
issue resolved.
panel.

Is normal video restored?

Issue resolved.
Confirm that the computer Yes ${nodeText.yesSymptomCode}
display flickering or unstable
video issue is resolved.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
15. available, to ensure no other ESCALATION
issues remain. No REQUIRED. ${nodeText.noSymptomCode}

Verify that the issue is resolved. Contact ACS for

additional support
or a multiple-part
Is the issue resolved? repair.
Audio-in Jack Issues
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, DisplayPort cable, hard disk drive (HDD), hard drive
data or power or combo cable, display panel, left speaker, memory, power supply, right speaker, solid-state drive (SSD)/flash
storage card, stand, Wi-Fi/Bluetooth antennas, wireless card

Quick Check

Symptoms Quick Check

1. Use controls to adjust sound volume and ensure that
audio output is not muted.
2. Ask user which type of audio input cable is connected to
the computer's audio-in jack: analog or optical cable.

Important: Some iMac models do not support optical audio.

Refer to Apple product specifications for more information.

3. Use macOS Recovery to troubleshoot potential software

issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
4. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure system build is correct for this computer
model. Check for and apply the latest software and
firmware updates.
5. Check that a known-good audio cable is used with the
analog 3.5 mm stereo mini plug end connected to the
proper input on the computer and the other end
connected to a compatible line-level audio source.
6. Check that a known-good analog audio device (such as
an iPod, iPhone, or Mac) is used as a source and is
playing audio.
7. On the user's computer, go to System Preferences >
Sound and verify the following:

Input tab:
“Line In” input source is available and selected
when an analog audio source is connected.
“Input volume” slider is not set to zero (available
only with an analog audio input).
Output tab:
Sound output device is set to Internal Speakers.
Output volume is not muted or set to zero.
External audio-in port does not work with an analog or
8. Open QuickTime Player. Choose “New Audio
digital line-level source Recording” from File menu. Choose “Built-in Input: Line
In” input source from right pop-up menu and adjust
Note: Inform user that computer failures due to accidental sound volume using slider in center of window.
damage are not covered. If applicable, discuss out-of-
9. If audio is heard, then verify user's cable and audio
warranty repair options. device using same process.

Note: Disconnecting an analog stereo mini plug cable

from the iPod/iPhone side will pause audio playback.

8. Perform visual and mechanical inspection of audio input

and output jacks. Use an otoscope to inspect for dust
and/or debris. Use compressed air to clean and remove
any dust and/or debris.
9. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.
 Before removing any components, be sure to turn off the
computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive

Check Result Action Code Commodity

Play a known-good audio Go to step 3.
Yes ${nodeText.yesSymptomCode}
file or reliable Internet radio
station via iTunes. Verify
that sound is clearly audible
and free of distortion
1. through both headphones
Go to step 2.
and internal speakers. No ${nodeText.noSymptomCode}

Does the audio file play

correctly?
Specify whether playback Go to “Distorted Audio from
from known-good audio Internal Speaker(s)”
Distorted ${nodeText.yesSymptomCode}
source is distorted or not troubleshooting flow.
audible.
2.
Go to “No Audio from Internal
Not Speaker(s) or Headphone Jack”
${nodeText.noSymptomCode}
Is sound distorted or not Audible troubleshooting flow.
audible?
Go to step 4.
Yes ${nodeText.yesSymptomCode}
Hold down Command-R Reinstall macOS on the user's
during startup to restart from computer. Refer to HT204319:
recovery partition, and try to
Use the Mac operating system
reproduce audio input issue
that came with your Mac, or a
using known-good audio
3. compatible newer version to
sources and cables.
No check that the system build is ${nodeText.noSymptomCode}
correct for this computer model.
Does audio issue persist Check for and apply the latest
with known-good OS? software and firmware updates.
Verify resolution.

From user information, Analog Go to step 5.

${nodeText.yesSymptomCode}
identify whether analog line- Line-in
in or optical digital-in is
causing issue.

Some iMac models do not

support optical audio. Refer
4. to Apple product
Optical Go to step 10.
specifications for more ${nodeText.noSymptomCode}
Digital-in
information.

Which audio input is

affected: analog line-in or
optical digital-in?
 Check Result Action Code Commodity
Go to step 6.
Yes ${nodeText.yesSymptomCode}

To troubleshoot this issue

completely, a known-good
3.5 mm stereo cable is
required.
5. ESCALATION REQUIRED.
No ${nodeText.noSymptomCode}
Do you have immediate Computer analog input cannot
access to a known-good 3.5 be tested without an adequate
mm stereo cable? 3.5 mm male-to-male stereo
mini plug cable.

Disconnect any cable from Go to step 8.

Yes ${nodeText.yesSymptomCode}
audio in (mic) port to verify
default setting for audio in.

In System Preferences >

Sound > Input, verify that
the Line In audio input
source is listed and that the
6. Input volume slider is
Go to step 7.
present. No ${nodeText.noSymptomCode}

Set Input volume to middle

position.

Is Line In audio input

available?
Line in activity appears to be Issue resolved by resetting
stuck to optical digital-in audio-in jack. To prevent the
mode: issue from recurring suggest
that user check physical
Yes ${nodeText.yesSymptomCode}
Insert a 3.5 mm stereo specifications of cable
mini plug into the connectors previously
audio in port and then connected to this jack.
rapidly unplug it and
plug it in several times
to reset internal
switches in the
connector.
Verify whether System
Preferences > Sound
7.
> Input reverts to Line
In after plug insertion
and removal.
Close and reopen Go to step 14.
No ${nodeText.noSymptomCode}
Sound Preferences
window to refresh list
of current audio input
sources.

Does audio input in System

Preferences revert to Line In
after minijack insertion and
removal?
 Check Result Action Code Commodity
Play a known-good audio Go to step 9.
Yes ${nodeText.yesSymptomCode}
file or Internet radio station
in iTunes, and verify that it
plays through internal
speakers.

Connect 3.5 mm male-to-

male stereo mini plug cable
between the audio in (mic)
port and the audio out
(headphone) port.

In System Preferences >

Sound > Output verify that
8. Headphones audio output
Go to step 14.
source appears and select No ${nodeText.noSymptomCode}
it.

In System Preferences >

Sound > Input, select Line
In, then adjust the Input
volume slider to observe
activity level without peaking
at maximum.

Does the bar graph at

bottom of recording window
show input activity?
Open QuickTime Player and Computer analog audio input
choose New Audio appears to be performing to
Recording from File menu. Yes specifications. Verify issue ${nodeText.yesSymptomCode}
resolved.
In the new recording
window, choose "Built-In:
Line Input" source from
input source right pop-up
menu. Adjust volume using
slider in center of window.

Press record button to start

recording. Record for
several seconds, then click
record button again to stop
recording.

9. Disconnect stereo cable

from audio out (headphone)
port to hear audio through Go to step 14.
No ${nodeText.noSymptomCode}
internal speakers. If needed,
press F11-F12 keys to
adjust volume, and confirm
that computer is able to play
sound.

Stop playing known-good

audio file or Internet radio.

Play recorded audio file.

Does computer accurately

reproduce sound recorded
from audio input?
 Check Result Action Code Commodity
Go to step 11.
Yes ${nodeText.yesSymptomCode}

To troubleshoot this issue

completely, a known-good
3.5 mm mini-TOSLINK
optical cable is required.
10. ESCALATION REQUIRED.
No ${nodeText.noSymptomCode}
Do you have immediate Computer digital input cannot be
access to a known-good 3.5 tested without adequate 3.5 mm
mm mini-TOSLINK cable? mini-TOSLINK male-to-male
optical cable.

Connect 3.5 mm mini- Go to step 12.

Yes ${nodeText.yesSymptomCode}
TOSLINK cable to the audio
out (headphone) port.

In System Preferences >

Sound > Output, verify that
a Digital Out audio output
source appears, and select
it.

Play a known-good audio

file or Internet radio station.
11.
Go to step 14.
No ${nodeText.noSymptomCode}
Audio out should switch to
optical digital audio, and
unplugged end of cable will
emit a red light to indicate
transmission of a digital
audio stream.

Is red light visible at

unplugged end of mini-
TOSLINK cable?
Continue to play known- Go to step 13.
Yes ${nodeText.yesSymptomCode}
good audio.

Connect other end of 3.5

mm mini-TOSLINK cable to
audio in (mic) port.

Open QuickTime Player and

choose New Audio
Recording from File menu.
12.
In the new recording Go to step 14.
No ${nodeText.noSymptomCode}
window, choose "Built-in
Input: Digital In" from the
input source pop-up menu,
and adjust volume using
slider in center of window.

Does the bar graph at

bottom of the recording
window show input activity?
 Check Result Action Code Commodity
Press record button to start Computer digital audio input
recording. Record for appears to be performing to
several seconds. Press Yes specifications. Verify issue ${nodeText.yesSymptomCode}
record button again to stop resolved.
recording.

Disconnect optical cable

from audio out (headphone)
port to hear audio through
internal speakers. Press
F11 and F12 keys to adjust
volume, and confirm that
13.
computer is able to play
sound.
Go to step 14.
No ${nodeText.noSymptomCode}
Stop playing known-good
audio.

Play the recorded audio file.

Does computer accurately

reproduce sound recorded
from audio input?
Disconnect cable from audio Replace logic board. Verify
in (mic). Open QuickTime Yes issue resolved. M09 MLB
Player and choose New
Audio Recording from the
File menu. Choose "Built-in
Microphone: Internal
Microphone" from the pop-
up menu to record from an
internal microphone input
14. source. Compare distortion
between recorded internal Go to step 15.
No ${nodeText.noSymptomCode}
input and external input
sources.

Is recorded sound also

distorted when recorded
from internal microphone
input?
 Check Result Action Code Commodity
Disconnect headphones or Issue resolved by reseating
external speakers. Yes audio cable. Verify resolution. ${nodeText.yesSymptomCode}

Turn off computer. Unplug

computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC
mains before proceeding.

Remove display panel.

Inspect audio cable

connector and its
corresponding connector on
15. logic board. Reseat
connection and retest. Go to step 16.
No ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting
with the display panel
removed.

Is recorded sound audible,

clear, and free of distortion?
Go to step 17.
Yes ${nodeText.yesSymptomCode}

ESCALATION REQUIRED.

To troubleshoot this issue Audio I/O ports are part of the

completely, a known-good rear enclosure. Replace the rear
rear enclosure is required. enclosure. Verify issue resolved.
16.
No Inform user that failures due to X99
Do you have immediate accidental damage are not
access to a known-good covered by Apple’s one-year
rear enclosure? limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.
 Check Result Action Code Commodity

Substitute a known-good ESCALATION REQUIRED.

rear enclosure with audio
ports and retest recording. Audio I/O ports are part of the
rear enclosure. Replace the rear
To do this, carefully place enclosure. Verify issue resolved.
known-good rear enclosure
near the user's computer, Yes Inform user that failures due to X99
then temporarily plug audio accidental damage are not
17. covered by Apple’s one-year
flex cable from known-good
rear enclosure into audio limited warranty or the
connector on the logic board AppleCare Protection Plan.
inside user's computer. Refer to
www.apple.com/legal/warranty.

Is recorded sound audible, Contact ACS for additional

clear, and free of distortion? support regarding warranty
coverage for this part.

Replace logic board. Verify

No issue resolved. M09 MLB

Plug a known-good analog Issue resolved.

Yes ${nodeText.yesSymptomCode}
audio source into audio in
jack, and verify that sound
recorded is audible and free
of distortion.

Repeat with digital (optical)

audio source (for models
that support digital optical
audio only).
18.
Run ASD or AST 2 Full No ESCALATION REQUIRED. X99
System Diagnostic (EFI &
OS), if available, to ensure Contact ACS for additional
no other issues remain. support or a multiple-part repair.

Verify that the issue is

resolved.

Is issue resolved?
Camera Issues
Unlikely causes:
Battery, fan, DisplayPort cable, left speaker, memory, power supply, rear enclosure, right speaker, flash storage card, stand,
Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

1. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.
2. Verify that the camera lens and display are clean and
clear of contaminants.
3. Verify that another application is not using the camera.
Refer to HT201715: “Your camera is in use by another
application” message .
4. Ask user about lighting conditions in his or her working
environment. Dim lighting causes poor image quality.
Overly bright lighting can bounce off surfaces onto
subject and make image foggy.
5. Striped, textured, and mesh clothing can create moiré
patterns in image.
6. Reset SMC using the procedure listed for this computer
Camera not detected in article HT201295: How to reset the System
No green LED for camera Management Controller (SMC) on your Mac to return
Excessive blooming computer to a known power-off state. Try to turn on from
Poor white balance power-off state. Do not hold in the power button when
Poor focus resetting the SMC. You could inadvertently put the
Green image computer into DFU mode if you do.
Image distortion 7. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
Note: Inform user that computer failures due to accidental 8. Disconnect all peripheral devices and restart computer.
damage are not covered. If applicable, discuss out-of-
warranty repair options. Warning: Be extremely careful when working inside the
computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Check Mac Resource Inspector Go to step 2.
Yes ${nodeText.yesSymptomCode}
(MRI) results to verify that the
camera is detected.

If AST 1 or AST 2 is not

available, use System
Information to verify that the
FaceTime HD Camera is
recognized.
1.
Go to step 3.
The camera will be listed in No ${nodeText.noSymptomCode}
System Information > Hardware
> Camera Device Tree. Verify
that “FaceTime HD Camera
(Internal)” is listed.

Does MRI or System Information

detect the camera?
Launch Photo Booth. Verify that Go to step 4.
Yes ${nodeText.yesSymptomCode}
the green LED next to the
camera illuminates when an
2. image is present in Photo Booth.
Go to step 3.
No ${nodeText.noSymptomCode}

Does the camera LED light up?

Follow steps listed in HT208198: Reinstall macOS on
About Boot Security Utility to the user’s
enable starting up from an computer. Refer to
external storage device on the HT201260: How to
user’s computer. find the macOS
version number on
Start up computer using an up- your Mac to check
to-date, bootable macOS that the system
Yes ${nodeText.yesSymptomCode}
volume. See articles HT201314: build is correct for
3. About macOS Recovery and this computer
HT201260: How to find the model. Check for
macOS version number on your and apply the latest
Mac. software and
firmware updates.
Retest the camera. Verify resolution.

Go to step 5.
Does the camera function No ${nodeText.noSymptomCode}
properly in a known-good OS?
The issue is
Verify that the camera image is
resolved. Verify
clear and undistorted. Yes ${nodeText.yesSymptomCode}
resolution.
4.
Go to step 5.
Is the image clear? No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 6.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding.

Remove display panel.

Locate and disconnect the

camera/front microphone/ALS
5. cable from the logic board and
Go to step 7.
camera. No ${nodeText.noSymptomCode}

Inspect both ends of the cable,

the logic board connector, and
the camera connector for any
damage.

Is there any damage to the

camera/front microphone/ALS
cable or any connectors?
Replace the
camera/front
microphone/ALS
cable. INTERNAL
Yes X03
CABLE
Verify that the issue
Determine whether the damage is resolved.
is located on the camera/front
microphone/ALS cable, the logic
board, the camera, or a
combination of multiple
6. components.

ESCALATION
Is the damage limited to the REQUIRED.
camera/front microphone/ALS No X99
cable cable only? Contact ACS for
additional support
or a multiple-part
repair.

Reseat camera/front Go to step 8.

Yes ${nodeText.yesSymptomCode}
microphone/ALS cable securely
to logic board and camera.

Turn on computer and check

System Information again.

Warning: HIGH VOLTAGE: The

power supply remains
energized whenever the
7.
computer is plugged in, Go to step 9.
No ${nodeText.noSymptomCode}
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does camera appear in System

Information?
 Check Result Action Code Commodity
Issue resolved by
Launch Photo Booth. Verify that
reseating the
green LED next to camera lights
camera/front
up. Make sure image looks
Yes microphone/ALS ${nodeText.yesSymptomCode}
normal.
8. cable. Verify
resolution.
Does camera LED light up and
Go to step 11.
image appear normal? No ${nodeText.noSymptomCode}
Go to step 10.
To troubleshoot this issue Yes ${nodeText.yesSymptomCode}
completely, a known-good
Replace
camera/front microphone/ALS
camera/front
cable is required.
microphone/ALS
9.
cable. INTERNAL
No X03
CABLE
Do you have immediate access
Verify that the issue
to a known-good camera/front
is resolved.
microphone/ALS cable?
Replace
camera/front
Substitute a known-good microphone/ALS
camera/front microphone/ALS cable. INTERNAL
Yes X03
cable and retest. CABLE
10.
Verify that the issue
is resolved.
Is camera working normally?
Go to step 11.
No ${nodeText.noSymptomCode}
The camera is part of the display Go to step 12.
Yes ${nodeText.yesSymptomCode}
panel in this model.
Replace display
To troubleshoot this issue panel, which
completely, a known-good includes the
11.
display panel is required. camera.
No L17 LCD
Verify issue
Do you have immediate access resolved.
to a known-good display panel?
Replace display
panel, which
includes the
camera.
Yes L17 LCD
Verify issue
resolved.
Substitute a known-good display
panel and retest. Replace logic
12. board.

Is camera working normally? Use Blank Board

Serializer (BBS) to
No set the computer’s M13 MLB
serial number.

Verify that the issue

is resolved.
 Check Result Action Code Commodity
Issue resolved.
Yes ${nodeText.yesSymptomCode}
Confirm that the computer’s
FaceTime camera is recognized
and functional.

Run AST 2 Full System

Diagnostic (EFI & OS), if ESCALATION
13. available, to ensure no other REQUIRED.
issues remain. No M99
Contact ACS for
Verify that the issue is resolved. additional support
or a multiple-part
repair.
Is issue resolved?
Distorted Audio from Internal Speaker(s)
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, DisplayPort cable, flash storage card/solid-state drive
(SSD), hard disk drive (HDD), hard drive data or power or combo cable, display panel, memory, power supply, stand, Wi-
Fi/Bluetooth antennas, wireless card

Quick Check

Symptoms Quick Check

1. Test with a known-good stereo sound file.
2. Compare the same sound and settings against a known-
good similar model computer to make sure sound is
indeed distorting.
3. In System Preferences > Sound > Output, adjust the
Output volume and use Balance slider to isolate left and
right speakers. Check whether issue only happens with
one speaker.
4. If testing with iTunes, make sure both equalizer and
preamp settings are set to Flat.
5. Test audio output using more than one application or
website.
6. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
7. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure system build is correct for this computer
model. Check for and apply the latest software and
Sound is distorted, fuzzy, or crackly. firmware updates.
Symptom only appears in internal speaker.
Symptom also appears in external Warning: Be extremely careful when working inside the
speakers/headphones. computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
Note: Inform user that computer failures due to accidental is plugged in. Always cover the power supply and logic board
damage are not covered. If applicable, discuss out-of- with power supply covers to protect yourself when working
warranty repair options. inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Start up computer using an Go to step 2.
Yes ${nodeText.yesSymptomCode}
up-to-date, bootable macOS
volume. See articles Reinstall macOS on the user's
HT201314: About macOS computer. Refer to HT204319:
Recovery and HT204319: Use the Mac operating system
Use the Mac operating that came with your Mac, or a
1. system that came with your compatible newer version to
Mac, or a compatible newer No check that the system build is ${nodeText.noSymptomCode}
version. correct for this computer model.
Check for and apply the latest
software and firmware updates.
Does the audio issue persist Verify resolution.
from a known-good OS?
Play known-good audio file Go to step 3.
Yes ${nodeText.yesSymptomCode}
on internal speakers, then
connect known-good
headphones or external
speakers and compare for
2. distortion.
Go to step 7.
No ${nodeText.noSymptomCode}

Is sound also distorted

through headphones or
external speakers?
Turn off computer. Unplug Go to step 4.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding.

Remove display panel.

3.
Go to step 5.
Inspect audio cable to audio No ${nodeText.noSymptomCode}
I/O ports and its
corresponding connection on
logic board.

Did you find damage to

audio cable or logic board
connector?
Replace the logic board. Verify
Yes that the issue is resolved. M09 MLB

ESCALATION REQUIRED.

Determine whether damage Audio I/O ports are part of the

is on the logic board, audio rear enclosure. Replace the rear
cable, or both. enclosure. Verify issue resolved.
4.
No Inform user that failures due to ${nodeText.noSymptomCode}
Is the damage limited to accidental damage are not
logic board? covered by Apple’s one-year
limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.
 Check Result Action Code Commodity
To troubleshoot this issue Go to step 6.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
logic board is required.
5. Replace the logic board. Verify
No that the issue is resolved. M09 MLB
Do you have immediate
access to a known-good
logic board?
Replace the logic board. Verify
Yes that the issue is resolved. M09 MLB

ESCALATION REQUIRED.

Substitute known-good logic Audio I/O ports are part of the

board and retest. rear enclosure. Replace the rear
enclosure. Verify issue resolved.

6. Inform user that failures due to

Is sound through
headphones or external No accidental damage are not ${nodeText.noSymptomCode}
speakers audible, clear, and covered by Apple’s one-year
free of distortion? limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.

Run AST 1 or AST 2 Audio

Test to verify left and right
speakers produce expected
audio test patterns from
each speaker. Yes ESCALATION REQUIRED. X99
7.
Refer to article TP587: Using Contact ACS for additional
Audio Test. support or a multiple-part repair.

Go to step 8.
Does unit pass Audio Test? No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 9.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding.

Remove display panel.

Locate speaker connections

on logic board. Disconnect
and inspect both speaker
8. cable connectors and
Go to step 10.
corresponding connectors on No ${nodeText.noSymptomCode}
logic board for damage.

Reconnect the left and right

speakers to the logic board,
verifying that the
connections are all seated
properly.

Did you find damage to

speakers or logic board
connector?
Speakers are replaced as a
matched set. Replace speakers
with a matched-pair replacement
OTHER
Yes kit. X08
ELECTRIC
Determine whether damage Verify that the issue is resolved.
is on the logic board,
speakers, or both.
9.

Is the damage limited to

speaker(s)?
No ESCALATION REQUIRED. X99

Contact ACS for additional

support or a multiple-part repair.
 Check Result Action Code Commodity
With speaker connectors The issue was resolved by
reseated to logic board, reseating cables. Verify
Yes ${nodeText.yesSymptomCode}
verify you can hear audio resolution.
through internal speakers.

In System Preferences >

Sound > Output tab, adjust
Balance slider to check left
and right speaker channel
separation.

Play music with high and low

tones to check bass and
tweeter performance of left
and right speakers.
10.
Warning: HIGH VOLTAGE: Go to step 11.
No ${nodeText.noSymptomCode}
The power supply remains
energized whenever the
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting with
the display panel removed.

Is sound from affected

speaker audible, clear, and
free of distortion?
Inspect and carefully clean Issue resolved by cleaning the
affected speaker cone using speaker membrane. Verify
Yes ${nodeText.yesSymptomCode}
a soft tissue to remove dust, resolution.
debris, or foreign material
such as metal fragments that
easily adhere to the
magnetic speaker. Reseat
11.
speaker connection and
retest. Go to step 12.
No ${nodeText.noSymptomCode}

Is sound from affected

speaker audible, clear, and
free of distortion?
To troubleshoot this issue Go to step 13.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
internal speaker set is
required.

Internal speakers are

specified to work as a
matched pair and must be Speakers are replaced as a
tested or replaced as matched set. Replace speakers
12. matched pairs. with a matched-pair replacement
OTHER
No kit. X09
ELECTRIC
Keep and identify your
known-good speakers from Verify that the issue is resolved.
one kit as a matched pair.

Do you have immediate

access to a known-good
speaker set?
 Check Result Action Code Commodity
Substitute a known-good Speakers are replaced as a
internal speaker set and matched set. Replace speakers
verify you can hear audio with a matched-pair replacement
OTHER
through internal speakers. Yes kit. X09
ELECTRIC
Retest using AST 1 or AST 2 Verify that the issue is resolved.
Audio Test to verify left and
right speakers produce
expected audio test patterns
from each speaker.

Refer to article TP587: Using

Audio Test.
13.
Warning: HIGH VOLTAGE:
The power supply remains Replace the logic board. Verify
energized whenever the No that the issue is resolved. M09 MLB
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting with
the display panel removed.

Does unit pass Audio Test?

Connect and disconnect The issue is resolved. Verify
headphones/external Yes resolution. ${nodeText.yesSymptomCode}
speakers. Verify that audio
can be played through both
external and internal
speakers, and that sound is
clear and free of distortion.

Run ASD or AST 2 Full

14.
System Diagnostic (EFI &
OS), if available, to ensure No ESCALATION REQUIRED. X99
no other issues remain.
Contact ACS for additional
Verify that the issue is support or a multiple-part repair.
resolved.

Is the issue resolved?

External Apple Bluetooth Peripherals
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

Apple Bluetooth wireless keyboard, mouse, or trackpad IMPORTANT:
is not recognized by known-good computer This troubleshooting procedure is intended only for Apple
Apple Bluetooth wireless keyboard, mouse, or trackpad Bluetooth wireless peripheral devices, such as the following
will not pair with known-good computer Apple products:
Apple Bluetooth wireless keyboard, mouse, or trackpad
intermittently loses its connection Magic Mouse or Magic Mouse 2
Apple wireless keyboard has one or more of the Magic Trackpad or Magic Trackpad 2
following issues: Apple Wireless Keyboard or Magic Keyboard
No power
Battery will not charge (for peripherals with For simplicity, this procedure refers to these products as
embedded batteries) wireless mouse, wireless trackpad, and wireless keyboard
Swollen battery (for peripherals with embedded unless otherwise noted.
batteries)
Battery runtime too short For third-party devices, contact the manufacturer for support,
Will not turn off software/firmware updates, or service options.
Specific key(s) do not work
Keys seem to stick, do not respond properly, or 1. Check for and apply the latest software and firmware
respond slowly updates.
Wrong keyboard language 2. In System Preferences, make sure Bluetooth is on and
Keys missing or falling off keyboard set to Discoverable.
Paint is wearing off of one or more keys on the 3. For Apple Bluetooth peripherals with replaceable
keyboard batteries, such as the Magic Mouse, Magic Trackpad, or
Physical and/or cosmetic issues Apple Wireless Keyboard: If the device does not turn on,
Apple wireless mouse has one or more of the following then install new or freshly charged batteries.
issues: 4. For Apple Bluetooth peripherals with embedded
No power batteries, such as the Magic Mouse 2, Magic Trackpad
Battery will not charge (for peripherals with 2, or Magic Keyboard: If the device does not turn on,
embedded batteries) then connect a known-good USB Power Adapter and
Swollen battery (for peripherals with embedded Lightning cable to the device to charge it for at least two
batteries) minutes. Switching the device power button or switch to
Battery runtime too short the ON position will allow the device to charge more
Will not turn off quickly than when OFF.
No mouse response 5. For Apple Bluetooth peripherals with embedded
Mouse click not recognized batteries such as the Magic Mouse 2, Magic Trackpad 2,
Mouse causes erratic cursor tracking or Magic Keyboard, verify that the computer being used
Physical and/or cosmetic issues with the peripheral supports Bluetooth 4.0 or later.
Apple wireless trackpad has one or more of the Computers with earlier versions of Bluetooth support will
following issues: not pair with Apple Bluetooth peripherals with embedded
No power batteries.
Battery will not charge (for peripherals with 6. Reset Bluetooth device or delete pairing (if applicable).
embedded batteries) 7. If Bluetooth pairs normally at your service location, then
Swollen battery (for peripherals with embedded research potential sources of interference in the user’s
batteries) environment, such as microwave ovens or cordless
Battery runtime too short phones in the 2.4/5GHz range. See article HT201542:
Will not turn off Potential sources of Wi-Fi and Bluetooth interference.
No trackpad response 8. Magic Mouse 2, Magic Trackpad 2, and Magic
Trackpad click not recognized Keyboard, can pair with the computer using either
Trackpad causes erratic cursor tracking Bluetooth or a Lightning cable. If Bluetooth pairing is not
Trackpad requires high click force possible due to interference or other reasons, then try
Trackpad click overly sensitive pairing these products by connecting them to the known-
Force Touch or haptic feedback issue good computer with a known-good Lightning cable.
Physical and/or cosmetic issues 9. Follow steps listed in HT204066: Use Bluetooth
Diagnostics to help you isolate issues with wireless
Note: Inform user that computer failures due to accidental devices.
damage are not covered. If applicable, discuss out-of- 10. For keyboard issues, refer to HT204540: If your Apple
warranty repair options. keyboard doesn’t work for troubleshooting tips.

Deep Dive
 Check Result Action Code Commodity
Visually inspect the user’s Go to step 2.
Yes ${nodeText.yesSymptomCode}
wireless mouse, wireless
trackpad, or wireless keyboard
for any for physical, cosmetic,
and/or liquid damage.

On a wireless mouse or wireless

trackpad, verify that the mouse
or trackpad button clicks.
1.
Go to step 11.
On keyboards, verify that all No ${nodeText.noSymptomCode}
keyboard buttons are present
and can be depressed normally.

Does the user’s wireless

mouse, wireless trackpad, or
wireless keyboard show signs of
damage?
Go to step 3.
Yes ${nodeText.yesSymptomCode}

Determine whether there is a

safety issue, such as fumes,
excessive heat, or shock.

Do not perform procedures that ESCALATION

2. REQUIRED.
can be a safety risk to you or the
No ${nodeText.noSymptomCode}
user.
Contact ACS for
additional support
Can you proceed safely? regarding safety
procedures for
this product.

Isolate damage issue to either Wireless Go to step 4.

${nodeText.yesSymptomCode}
user’s wireless keyboard, or keyboard
wireless mouse or trackpad.
3. Wireless
Go to step 8.
mouse or ${nodeText.noSymptomCode}
trackpad
Which peripheral is damaged?
Closely examine the user’s Replace the
device to determine exact nature user’s wireless
of the issue. Yes keyboard out of K90 KEYBOARD
warranty.
Look for any signs of liquid spill,
4. liquid penetration, or liquid
damage to device.
Go to step 5.
No ${nodeText.noSymptomCode}
Is damage to user’s device
related to liquid spill?
Closely examine the user’s Replace the
device for any signs of physical user’s wireless
damage that may affect Yes keyboard out of K16 KEYBOARD
operation. warranty.
5.

Go to step 6.
Does the user’s device exhibit No ${nodeText.noSymptomCode}
this symptom?
Closely examine the user’s Replace the
device for signs of paint wearing user’s wireless
off of one or more keys. Yes keyboard out of K35 KEYBOARD
6. warranty.

Does the user’s device exhibit Go to step 7.

No ${nodeText.noSymptomCode}
this symptom?
 Check Result Action Code Commodity
Closely examine the user’s Replace the
device for any signs of cosmetic user’s wireless
damage that does not affect Yes keyboard out of K21 KEYBOARD
operation. warranty.
7.
Issue cannot be
Does the user’s device exhibit No duplicated. ${nodeText.noSymptomCode}
this symptom?
Closely examine the user’s Replace the
device to determine exact nature user’s wireless
of the issue. mouse or
Yes K90 MOUSE
wireless trackpad
Look for any signs of liquid spill, out of warranty.
8. liquid penetration, or liquid
damage to device.
Go to step 9.
No ${nodeText.noSymptomCode}
Is damage to user’s device
related to liquid spill?
Closely examine the user’s Replace the
device for any signs of physical user’s wireless
damage that may affect mouse or
Yes K16 MOUSE
operation. wireless trackpad
9.
out of warranty.

Does the user’s device exhibit Go to step 10.

No ${nodeText.noSymptomCode}
this symptom?
Replace the
Closely examine the user’s
user’s wireless
device for any signs of cosmetic
mouse or
damage that does not affect Yes K21 MOUSE
wireless trackpad
operation.
10. out of warranty.

Issue cannot be
Does the user’s device exhibit
No duplicated. ${nodeText.noSymptomCode}
this symptom?

Follow steps listed in HT201171:

Using a Bluetooth mouse,
keyboard, or trackpad with your
Mac to pair the user’s Bluetooth
device with a known-good Mac. ESCALATION
REQUIRED.
Test the user’s wireless mouse,
wireless trackpad, or wireless The Bluetooth
keyboard manually, using built-in device appears to
applications on a known-good be performing to
Mac. For example, use the specifications.
Notes application to check the Yes There may be an ${nodeText.yesSymptomCode}
11. keys on a wireless keyboard. issue with the
user’s computer,
Refer to HT204621: If your Apple or wireless
wireless mouse, keyboard, or interference in
user’s
trackpad aren't working as
environment.
expected for tips to resolve
issues. If issue persists,
then contact ACS
for additional
Does the user’s wireless support.
mouse, wireless trackpad, or
wireless keyboard pair and
Go to step 12.
function normally? No ${nodeText.noSymptomCode}
Isolate failure to either user’s Wireless Go to step 13.
${nodeText.yesSymptomCode}
wireless keyboard, or wireless keyboard
mouse or trackpad.
12. Wireless Go to step 29.
mouse or ${nodeText.noSymptomCode}
Which peripheral is trackpad
malfunctioning?
 Check Result Action Code Commodity
Look for for any signs of power Go to step 14.
Yes ${nodeText.yesSymptomCode}
on the user’s wireless keyboard,
such as a power LED turning on.
Note: Not all devices have a
power LED.

Verify that the user’s wireless

keyboard turns ON when the
power button or switch is placed
in the ON position.
13.
Go to step 18.
No ${nodeText.noSymptomCode}
Verify that the user’s wireless
keyboard turns OFF when the
power button or switch is placed
in the OFF position.

Does the user’s wireless

keyboard exhibit any power-
related symptoms?
Confirm that the issue with the Replace the
user’s wireless keyboard is: user’s wireless
keyboard.
User’s wireless keyboard Yes K09 KEYBOARD
is not functioning at all Verify that the
(seems dead, no power, issue is resolved.
14.
power LED does not turn
on)
Go to step 15.
No ${nodeText.noSymptomCode}
Does the user’s wireless
keyboard exhibit this symptom?
Verify that the user’s wireless Replace the
keyboard turns ON when the user’s wireless
power button or switch is placed keyboard.
in the ON position. Yes K19 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless keyboard is:
15.
Power switch or button is
defective
Go to step 16.
No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
Verify that the user’s wireless Replace the
keyboard turns off when the user’s wireless
power button or switch is placed keyboard.
in the OFF position. Yes K34 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless keyboard is:
16.
User’s wireless keyboard
remains ON when power
button or switch has been
Go to step 17.
placed in the OFF position No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
 Check Result Action Code Commodity
Verify if the user’s wireless Replace the
keyboard has any other power- user’s wireless
related issue that is not related keyboard.
to the power button or switch. Yes K20 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless keyboard is:
17.
Power Issue, not due to
power button or switch
Go to step 18.
No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
If the user’s issue involves Go to step 19.
Yes ${nodeText.yesSymptomCode}
pairing or connecting to a Magic
Keyboard, then you can connect
to, pair, and use this device with
the computer using either
Bluetooth or a Lightning cable.

If Bluetooth pairing is not

possible due to interference or
other reasons, then try Replace the
connecting the user’s Magic user’s wireless
18. Keyboard to the known-good keyboard.
computer with a known-good No K30 KEYBOARD
Lightning cable. Verify that the
issue is resolved.
For other Apple Bluetooth
peripherals, select the “Yes”
answer to continue.

Does the user’s Magic

Keyboard connect and pair using
USB?
Verify that a known-good Replace the
computer can recognize the user’s wireless
user’s wireless keyboard. keyboard.
Yes K15 KEYBOARD
Confirm that the issue with the Verify that the
user’s wireless keyboard is: issue is resolved.
19.
User’s wireless keyboard
is not recognized by
known-good computer
Go to step 20.
No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
Verify that a known-good Replace the
computer can pair with the user’s wireless
user’s wireless keyboard using keyboard.
Bluetooth. Yes K07 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless keyboard is:
20.
User’s wireless keyboard
cannot pair with a known-
good computer Go to step 21.
No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
 Check Result Action Code Commodity
Verify that a known-good Replace the
computer maintains a Bluetooth user’s wireless
connection to the user’s keyboard.
wireless keyboard, and does not Yes K08 KEYBOARD
drop this connection. Verify that the
issue is resolved.
Confirm that the issue with the
user’s wireless keyboard is:
21.
User’s wireless keyboard
intermittently loses its
connection with a known- Go to step 22.
No ${nodeText.noSymptomCode}
good computer

Does the user’s wireless

keyboard exhibit this symptom?
Ask the user how often and how Go to step 23.
Yes ${nodeText.yesSymptomCode}
long the wireless keyboard is
used.

Explain to the user that the

battery issue could likely be
caused by the user using the
wireless keyboard continuously
over a long period of time, rather
than any fault of the wireless
keyboard itself, macOS, or the Replace the
user’s computer. user’s wireless
22. keyboard.
Gain agreement from the user No K32 KEYBOARD
that lengthy wireless keyboard Verify that the
usage is likely to be the cause of issue is resolved.
the battery life issue, and that
there is no service issue with the
wireless keyboard itself.

Does the user agree that the

battery life issue is likely caused
by lengthy wireless keyboard
usage?
Attempt to charge the user’s Replace the
wireless keyboard battery for user’s wireless
several more minutes. Verify that keyboard.
the user’s wireless keyboard Yes K31 KEYBOARD
battery charge level that appears Verify that the
on the known-good computer issue is resolved.
that is paired with this user’s
wireless keyboard has increased
and shows that the user’s
wireless keyboard is charging.

Confirm that the issue with the

23.
user’s wireless keyboard is:

User’s wireless keyboard

Go to step 24.
battery will not charge No ${nodeText.noSymptomCode}

Note: This symptom does not

apply to peripherals with
replaceable batteries.

Does the user’s wireless

keyboard exhibit this symptom?
 Check Result Action Code Commodity
Closely inspect the user’s Replace the
wireless keyboard enclosure for user’s wireless
signs of a swollen battery. keyboard.
Yes K33 KEYBOARD
Confirm that the issue with the Verify that the
user’s wireless keyboard is: issue is resolved.

User’s wireless keyboard

24. battery appears swollen

Note: This symptom does not

apply to peripherals with Go to step 25.
No ${nodeText.noSymptomCode}
replaceable batteries.

Does the user’s wireless

keyboard exhibit this symptom?
Verify that each and every Replace the
wireless keyboard key functions user’s wireless
as expected when pressed and keyboard.
released. Yes K01 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
25. user’s wireless keyboard is:

Specific key(s) do not work

Go to step 26.
No ${nodeText.noSymptomCode}
Does the user’s wireless
keyboard exhibit this symptom?
Verify that each and every Replace the
wireless keyboard key functions user’s wireless
as expected when pressed and keyboard.
released. Yes K05 KEYBOARD
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless keyboard is:
26.
Keys seem to stick, do not
respond properly, or
respond slowly Go to step 27.
No ${nodeText.noSymptomCode}

Does the user’s wireless

keyboard exhibit this symptom?
Verify that each and every Replace the
wireless keyboard key is intact user’s wireless
and not missing. keyboard.
Yes K27 KEYBOARD
Confirm that the issue with the Verify that the
user’s wireless keyboard is: issue is resolved.
27.
Keys missing or falling off
keyboard
Go to step 28.
No ${nodeText.noSymptomCode}
Does the user’s wireless
keyboard exhibit this symptom?
Verify that the wireless keyboard Replace the
language is as expected. user’s wireless
keyboard.
Confirm that the issue with the Yes K04 KEYBOARD
user’s wireless keyboard is: Verify that the
issue is resolved.
28.
Wrong keyboard language
version
Issue cannot be
No duplicated. ${nodeText.noSymptomCode}
Does the user’s wireless
keyboard exhibit this symptom?
 Check Result Action Code Commodity
Look for for any signs of power Go to step 30.
Yes ${nodeText.yesSymptomCode}
on the user’s wireless mouse or
trackpad, such as a power LED
turning on. Note: Not all devices
have a power LED.

Verify that the user’s wireless

mouse or trackpad turns ON
when the power button or switch
is placed in the ON position.
29.
Go to step 34.
No ${nodeText.noSymptomCode}
Verify that the user’s wireless
mouse or trackpad turns OFF
when the power button or switch
is placed in the OFF position.

Does the user’s wireless mouse

or trackpad exhibit any power-
related symptoms?
Confirm that the issue with the Replace the
user’s wireless mouse or user’s wireless
trackpad is: mouse or
trackpad.
Yes K09 MOUSE
User’s wireless mouse or
trackpad is not functioning Verify that the
at all (seems dead, no issue is resolved.
30.
power, power LED does
not turn on)

Go to step 31.
No ${nodeText.noSymptomCode}
Does the user’s wireless mouse
or trackpad exhibit this
symptom?
Verify that the user’s wireless Replace the
mouse or trackpad turns ON user’s wireless
when the power button or switch mouse or
is placed in the ON position. trackpad.
Yes K19 MOUSE
Confirm that the issue with the Verify that the
user’s wireless mouse or issue is resolved.
trackpad is:
31.
Power switch or button is
defective
Go to step 32.
No ${nodeText.noSymptomCode}
Does the user’s wireless mouse
or trackpad exhibit this
symptom?
Verify that the user’s wireless Replace the
mouse or trackpad turns off user’s wireless
when the power button or switch mouse or
is placed in the OFF position. trackpad.
Yes K34 MOUSE
Confirm that the issue with the Verify that the
user’s wireless mouse or issue is resolved.
trackpad is:

32. User’s wireless mouse or

trackpad remains ON when
power button or switch has
been placed in the OFF
Go to step 33.
position No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
 Check Result Action Code Commodity
Verify if the user’s wireless Replace the
mouse or trackpad has any other user’s wireless
power-related issue that is not mouse or
related to the power button or trackpad.
Yes K20 MOUSE
switch.
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless mouse or
33. trackpad is:

Power Issue, not due to

power button or switch
Go to step 34.
No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
If the user’s issue involves Go to step 35.
Yes ${nodeText.yesSymptomCode}
pairing or connecting to a Magic
Mouse 2 or Magic Trackpad 2,
then you can connect to and pair
these devices with a computer
using either Bluetooth or a
Lightning cable.

If Bluetooth pairing is not

possible due to interference or Replace the
other reasons, then try user’s wireless
connecting the user’s Magic mouse or
34.
Mouse 2 or Magic Trackpad 2 to trackpad.
No K30 MOUSE
a known-good computer with a
known-good Lightning cable. Verify that the
issue is resolved.
For other Apple Bluetooth
peripherals, select the “Yes”
answer to continue.

Does the user’s Magic Mouse 2

or Magic Trackpad 2 connect
and pair using USB?
Verify that a known-good Replace the
computer can recognize the user’s wireless
user’s wireless mouse or mouse or
trackpad. trackpad.
Yes K15 MOUSE
Confirm that the issue with the Verify that the
user’s wireless mouse or issue is resolved.
trackpad is:
35.
User’s wireless mouse or
trackpad is not recognized
by known-good computer.
Go to step 36.
No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
 Check Result Action Code Commodity
Verify that a known-good Replace the
computer can pair with the user’s wireless
user’s wireless mouse or mouse or
trackpad. trackpad.
Yes K07 MOUSE
Confirm that the issue with the Verify that the
user’s wireless mouse or issue is resolved.
trackpad is:
36.
User’s wireless mouse or
trackpad cannot pair with a
known-good computer
Go to step 37.
No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
Verify that a known-good Replace the
computer maintains a Bluetooth user’s wireless
connection to the user’s mouse or
wireless mouse or trackpad, and trackpad.
Yes K08 MOUSE
does not drop this connection.
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless mouse or
trackpad is:
37.
User’s wireless mouse or
trackpad intermittently
loses its connection with a
Go to step 38.
known-good computer No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
Ask the user how often and how Go to step 39.
Yes ${nodeText.yesSymptomCode}
long the wireless mouse or
trackpad is used.

Gain agreement from the user

that lengthy wireless mouse or
Replace the
trackpad usage is likely to be the
user’s wireless
cause of the battery life issue,
mouse or
38. and that there is no service issue
trackpad.
with the wireless mouse or No K32 MOUSE
trackpad itself.
Verify that the
issue is resolved.
Does the user agree that the
battery life issue is likely caused
by lengthy wireless device
usage?
 Check Result Action Code Commodity
Attempt to charge the user’s Replace the
wireless mouse or trackpad user’s wireless
battery for several more minutes. mouse or
Verify that the user’s wireless trackpad.
mouse or trackpad battery
Yes K31 MOUSE
charge level that appears on the Verify that the
known-good computer that is issue is resolved.
paired with this user’s wireless
mouse or trackpad has
increased and shows that the
user’s wireless mouse or
trackpad is charging.

Confirm that the issue with the

39. user’s wireless mouse or
trackpad is:

User’s wireless mouse or

trackpad battery will not
Go to step 40.
charge No ${nodeText.noSymptomCode}

Note: This symptom does not

apply to peripherals with
replaceable batteries.

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
Closely inspect the user’s Replace the
wireless mouse or trackpad user’s wireless
enclosure for signs of a swollen mouse or
battery. trackpad.
Yes K33 MOUSE
Confirm that the issue with the Verify that the
user’s wireless mouse or issue is resolved.
trackpad is:

User’s wireless mouse or

40. trackpad battery appears
swollen

Note: This symptom does not

Go to step 41.
apply to peripherals with No ${nodeText.noSymptomCode}
replaceable batteries.

Does the user’s wireless mouse

or trackpad exhibit this
symptom?
Isolate failure to either user’s Wireless Go to step 42.
${nodeText.yesSymptomCode}
wireless mouse or wireless mouse
trackpad.
41.
Wireless Go to step 45.
${nodeText.noSymptomCode}
trackpad
Which peripheral is
malfunctioning?
 Check Result Action Code Commodity
Verify that the overall function of Replace the
the user’s wireless mouse user’s wireless
performs as expected when mouse.
used with the known-good Yes K26 MOUSE
computer. Verify that the
issue is resolved.
Confirm that the issue with the
42.
user’s wireless mouse is:

No mouse response
Go to step 43.
No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

exhibit this symptom?
Verify that the clicking function of Replace the
the user’s wireless mouse user’s wireless
performs as expected when mouse.
pressed and released. Yes K14 MOUSE
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless mouse is:
43.
Mouse clicking function not
working properly
Go to step 44.
No ${nodeText.noSymptomCode}

Does the user’s wireless mouse

exhibit this symptom?
Verify that the touch gesture Replace the
function of the user’s wireless user’s wireless
mouse performs as expected mouse.
when the mouse surface is Yes K18 MOUSE
touched. Verify that the
issue is resolved.
Confirm that the issue with the
44. user’s wireless mouse is:

Touch/Multi-Touch gesture
Issue cannot be
issue
No duplicated. ${nodeText.noSymptomCode}

Does the user’s wireless mouse

exhibit this symptom?
Verify that the overall function of Replace the
the user’s wireless trackpad user’s wireless
performs as expected when trackpad.
used with the known-good Yes K23 MOUSE
computer. Verify that the
issue is resolved.
Confirm that the issue with the
45. user’s wireless trackpad is:

Trackpad cursor not

responding Go to step 46.
No ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
 Check Result Action Code Commodity
Verify that the user’s wireless Replace the
trackpad exhibits smooth user’s wireless
continuous tracking when used trackpad.
with the known-good computer, Yes K12 MOUSE
and does not skip or behave Verify that the
erratically. issue is resolved.

Confirm that the issue with the

46.
user’s wireless trackpad is:

Trackpad cursor not

Go to step 47.
tracking properly No ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
Verify that the clicking function of Replace the
the user’s wireless trackpad user’s wireless
performs as expected when trackpad.
pressed and released, and that Yes K13 MOUSE
the click is recognized by the Verify that the
known-good computer. issue is resolved.

Confirm that the issue with the

47.
user’s wireless trackpad is:

Trackpad click not

Go to step 48.
recognized No ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
Verify that the user’s wireless Replace the
trackpad clicking function does user’s wireless
not require excessive force when trackpad.
pressed and released. Yes K24 MOUSE
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless trackpad is:
48.
Trackpad requires high
click force
Go to step 49.
No ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
Verify that the user’s wireless Replace the
trackpad clicking function is not user’s wireless
overly sensitive to clicking when trackpad.
pressed and released. Yes K25 MOUSE
Verify that the
Confirm that the issue with the issue is resolved.
user’s wireless trackpad is:
49.
Trackpad click
oversensitive
Go to step 50.
No ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
 Check Result Action Code Commodity
Verify that the user’s wireless Replace the
trackpad Force Touch function user’s wireless
performs as expected and that trackpad.
haptic feedback is felt in Yes K29 MOUSE
response. Note: This feature Verify that the
does not apply to all models. issue is resolved.

Confirm that the issue with the

50.
user’s wireless trackpad is:

Trackpad Force Touch or Issue cannot be

haptic feedback issue No duplicated. ${nodeText.noSymptomCode}

Does the user’s wireless

trackpad exhibit this symptom?
External Apple Wired Keyboard and Mouse
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Disconnect all USB devices from the user’s computer
except for the user’s mouse or keyboard. Troubleshoot
only one device at a time to help isolate the issue.
2. Unplug the keyboard or mouse from the USB port, wait
a few seconds, and reconnect it.
3. Connect the keyboard or mouse to another USB port on
Apple wired USB keyboard or mouse does not function with the user’s computer.
user’s computer, or shows one or more of the following
4. Make sure the USB connectors are plugged in
symptoms: completely and correctly.
5. Visually inspect the USB connectors and ports for
Mouse button(s) does not click
damage or debris.
Mouse scroll ball does not operate smoothly
6. Try operating the user’s mouse on another surface. Ask
No mouse response the user about the type of surface usually being used
Keyboard keys stick with the mouse. Glossy or transparent surfaces, or those
Keyboard keys loose or missing
with repetitive patterns, may cause mouse-tracking
One or more keys do not respond when pressed errors or faulty mouse operation. Explain that solid, non-
No keyboard response at all reflective, opaque surfaces work best. The surface
Apple wired mouse causes erratic cursor tracking should be clean, but not shiny.
Apple wired keyboard or mouse is not recognized
7. Visually inspect the user’s keyboard or mouse for dirt,
Apple wired keyboard or mouse has physical damage
hair, liquid damage, or other debris. Check to see if the
that affects operation user has pets. Pet hair can lay across the laser and
Paint is wearing off of one or more keys on the keyboard cause intermittent mouse issues. Refer to article
Apple wired keyboard or mouse has cosmetic damage HT204172: How to clean your Apple products for
that does not affect operation
information on cleaning the user’s keyboard or mouse.
8. Connect the user’s USB keyboard or mouse to an
Note: Inform user that computer failures due to accidental
available USB port on a known-good computer to
damage are not covered. If applicable, discuss out-of-
determine if the issue is related to the USB port on the
warranty repair options.
user’s computer, or to the user’s USB keyboard or
mouse. If the user's keyboard or mouse functions when
used with a known-good computer, go to the “ USB Port
Not Recognized” troubleshooting flow.
9. For keyboard issues, refer to HT204540: If your Apple
keyboard doesn't work for troubleshooting tips.

Deep Dive
 Check Result Action Code Commodity
Visually inspect the user’s USB Go to step 2.
Yes ${nodeText.yesSymptomCode}
mouse or keyboard to verify that
the attached USB cable and/or
connector is not damaged or
frayed.

Check the user’s keyboard or

mouse for physical and/or liquid
damage.

On mice, verify that all mouse

1. buttons click and the laser
Go to step 12.
tracking LED illuminates. No ${nodeText.noSymptomCode}

On keyboards, verify that all

keyboard buttons are present
and can be depressed normally.

Does the user’s USB mouse or

keyboard, or its attached cable or
connector, show signs of
damage?
Isolate the damage issue to USB Go to step 3.
${nodeText.yesSymptomCode}
either the user’s wired USB Keyboard
keyboard or mouse.
2.
Go to step 9.
USB Mouse ${nodeText.noSymptomCode}
Which peripheral is damaged?
Replace USB
keyboard.
Verify issue
resolved.
Closely examine the user’s
keyboard to determine the exact Note: Inform
nature of its issue. user that
computer
Look for any signs of liquid spill, Yes failures due to K90 KEYBOARD
3. liquid penetration, or liquid accidental
damage to the keyboard. damage are not
covered. If
applicable,
Is damage to the user’s discuss out-of-
keyboard related to liquid spill? warranty repair
options.

Go to step 4.
No ${nodeText.noSymptomCode}
Replace USB
keyboard.
Verify issue
resolved.

Note: Inform
Click each key to ensure all keys
user that
are not sticking in the down or up
computer
position.
Yes failures due to K05 KEYBOARD
4. accidental
damage are not
Is damage to the user’s
covered. If
keyboard related to sticky keys or
applicable,
slow key response?
discuss out-of-
warranty repair
options.

Go to step 5.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Replace USB
keyboard.
Verify issue
resolved.

Note: Inform
Look for any loose or missing user that
keycaps. computer
Yes failures due to K27 KEYBOARD
5. accidental
Is damage to the user’s damage are not
keyboard related to loose or covered. If
missing keycaps? applicable,
discuss out-of-
warranty repair
options.

Go to step 6.
No ${nodeText.noSymptomCode}
Replace USB
keyboard.
Verify issue
resolved.

Note: Inform
Closely inspect the keyboard for user that
any signs of physical damage computer
that may affect operation. Yes failures due to K16 KEYBOARD
6. accidental
damage are not
Does the user’s keyboard covered. If
exhibit this symptom? applicable,
discuss out-of-
warranty repair
options.

Go to Step 7.
No ${nodeText.noSymptomCode}
Replace USB
keyboard.
Verify issue
resolved.

Note: Inform
Closely examine the keyboard for user that
signs of paint wearing off of one computer
or more keys. Yes failures due to K35 KEYBOARD
7. accidental
damage are not
Does the user’s keyboard covered. If
exhibit this symptom? applicable,
discuss out-of-
warranty repair
options.

Go to step 8.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Replace USB
keyboard.
Verify issue
resolved.

Note: Inform
user that
Closely inspect the keyboard for
computer
any signs of cosmetic damage
Yes failures due to K21 KEYBOARD
that does not affect operation.
accidental
8.
damage are not
covered. If
Does the user’s keyboard
applicable,
exhibit this symptom?
discuss out-of-
warranty repair
options.

Issue cannot be
No duplicated. ${nodeText.noSymptomCode}

Replace USB
mouse. Verify
issue resolved.
Closely examine user’s mouse
Note: Inform
to determine exact nature of the
user that
issue.
computer
failures due to
Look for any signs of liquid spill, Yes K90 MOUSE
accidental
9. liquid penetration, or liquid
damage are not
damage to mouse.
covered. If
applicable,
discuss out-of-
Is damage to user’s mouse
warranty repair
related to liquid spill?
options.

Go to step 10.
No ${nodeText.noSymptomCode}
Replace USB
mouse. Verify
issue resolved.

Note: Inform
user that
Closely inspect the mouse for
computer
any signs of physical damage
failures due to
that may affect operation. Yes K16 MOUSE
accidental
10.
damage are not
covered. If
Is there physical damage to
applicable,
user’s mouse?
discuss out-of-
warranty repair
options.

Go to step 11.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Replace USB
mouse. Verify
issue resolved.

Note: Inform
user that
Closely inspect the mouse for computer
any signs of cosmetic damage failures due to
Yes K21 MOUSE
that does not affect operation. accidental
11. damage are not
covered. If
Is there cosmetic damage to applicable,
user’s mouse? discuss out-of-
warranty repair
options.

Issue cannot be
No duplicated. ${nodeText.noSymptomCode}

Isolate failure issue to either Go to step 17.

USB
user’s wired USB keyboard or ${nodeText.yesSymptomCode}
Keyboard
mouse.
12.
Gp to step 13.
USB Mouse ${nodeText.noSymptomCode}
Which peripheral is
malfunctioning?
Connect user’s USB mouse to a Go to step 14.
Yes ${nodeText.yesSymptomCode}
free USB port on a known-good
computer, and check System
Information to determine
whether the computer recognizes Replace USB
13.
the mouse. mouse. Verify
No K15 MOUSE
issue resolved.

Is mouse recognized by a
known-good computer?
Move the mouse and verify that Replace USB
the cursor on the known-good mouse. Verify
Yes K26 MOUSE
computer screen moves issue resolved.
smoothly.
14.
Go to step 15.
No ${nodeText.noSymptomCode}
Is issue related to mouse
function?
Click and roll the mouse’s scroll Replace USB
ball to check that it rolls freely in mouse. Verify
Yes K06 MOUSE
all directions, with no physical issue resolved.
15. resistance.
Go to step 16.
No ${nodeText.noSymptomCode}
Is issue related to the scroll ball?
Click the mouse’s various Replace USB
buttons to verify they click mouse. Verify
Yes K14 MOUSE
properly, without sticking, each issue resolved.
time they are pressed.
16.
Issue cannot be
No duplicated. ${nodeText.noSymptomCode}
Is issue related to the mouse
button(s)?
Connect user’s USB keyboard Go to step 18.
Yes ${nodeText.yesSymptomCode}
to a free USB port on a known-
good computer, and check
System Information to
Replace USB
determine whether the computer
17. keyboard.
recognizes the keyboard.
No Verify issue K15 KEYBOARD
resolved.
Is keyboard recognized by a
known-good computer?
 Check Result Action Code Commodity
Verify that each and every Replace USB
keyboard key functions as keyboard.
expected when pressed and Yes Verify issue K01 KEYBOARD
released. resolved.
18.

Go to step 19.
Is issue related to specific keys No ${nodeText.noSymptomCode}
not working?
Replace USB
Verify that the keyboard keyboard.
language is as expected. Yes Verify issue K04 KEYBOARD
resolved.
19.
Is issue related to keyboard Issue cannot be
language? No duplicated. ${nodeText.noSymptomCode}
Internal Microphone Issues
Unlikely causes:
Battery, camera/front microphone/ALS cable, DisplayPort cable, fan, flash storage card, left speaker, memory, power supply,
right speaker, stand, Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

1. Identify the locations of all microphones (top front of
display next to camera, and on upper-rear enclosure),
and check that the microphone openings are not
covered by tape, sticky notes, or other obstructions.
Attempt to carefully remove any obstructions and verify
this resolves the issue.
2. On user’s computer go to System Preferences > Sound
and verify the following:

Input tab:
“Internal microphone” source is available and
selected.
Input volume slider is not set to zero.
Output tab:
Sound output device is set to Internal Speakers.
Output volume is not muted or set to zero.

3. Go to System Preferences > Sound > Input tab, and

verify that “Input level” indicator moves when speaking
into microphone.
4. Launch QuickTime Player. Choose New Audio
Recording from File menu. Choose Built-in Microphone
Microphone not working, but audio output is functional from right pop-up menu, and adjust input volume using
Microphone audio is garbled slider in center of window.
Internal microphone input cannot be selected 5. Check that no cables are inserted into audio input or
Line audio input functions properly output jacks. Use an otoscope to visually inspect both
jacks. Use compressed air to clean and remove any
Note: Inform user that computer failures due to accidental debris.
damage are not covered. If applicable, discuss out-of- 6. Reset the NVRAM using the procedure for this computer
warranty repair options. in article HT204063: How to Reset NVRAM on your Mac.
7. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates.

Warning: Be extremely careful when working inside the

computer with power applied and the system is energized.
Avoid touching the logic board or power supply while the
computer is plugged in. Always cover the power supply and
logic board with Power Supply Covers to protect yourself
when working inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Follow steps listed in Go to step 2.
Yes ${nodeText.yesSymptomCode}
HT208198: About Boot
Security Utility to enable
starting up from an external
storage device on the user’s
computer.
Reinstall macOS on the user’s
Start up computer using an
computer. Refer to HT201260:
up-to-date, bootable macOS
How to find the macOS version
volume. See articles
HT201314: About macOS number on your Mac to check
1.
that the system build is correct
Recovery and HT201260: No ${nodeText.noSymptomCode}
for this computer model. Check
How to find the macOS
for and apply the latest software
version number on your Mac.
and firmware updates. Verify
resolution.
Retest for microphone
issues.

Does issue persist with a

known-good OS?
Disconnect any connected Go to step 4.
Yes ${nodeText.yesSymptomCode}
headphones or external
speakers. Check whether
System Preferences >
Sound > Input tab shows an
“Internal microphone”
2. source available and
Go to step 3.
selected. No ${nodeText.noSymptomCode}

Does System Preferences

list “External microphone”
instead?
Run AST 2 Audio Test to
verify that built-in
microphones detect
expected audio test patterns
produced from each ESCALATION REQUIRED.
speaker. Yes X99
3. Contact ACS for additional
Refer to article TP587: Using support or a multiple-part repair.
Audio Test.

Does unit pass AST 2 Audio Go to step 4.

Test? No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 5.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding.

Remove display panel.

Locate and disconnect the

camera/front
4. microphone/ALS cable from
Go to step 6.
the logic board and camera. No ${nodeText.noSymptomCode}

Inspect both ends of the

cable, the logic board
connector, and the camera
connector for any damage.

Is there any damage to the

camera/front
microphone/ALS cable or
any connectors?
Replace the camera/front
microphone/ALS cable.
Determine whether the INTERNAL
Yes X03
damage is located on the CABLE
Verify that the issue is resolved.
camera/front
microphone/ALS cable, the
logic board, the camera, or a
combination of multiple
5. components.

ESCALATION REQUIRED.
No X99
Is the damage limited to the
camera/front Contact ACS for additional
microphone/ALS cable cable support or a multiple-part repair.
only?

Locate and disconnect the Go to step 7.

Yes ${nodeText.yesSymptomCode}
rear microphone cable from
the logic board and rear
microphone board.

Inspect both ends of the

cable, the logic board
6. connector, and the rear
Go to step 8.
microphone board connector No ${nodeText.noSymptomCode}
for any damage.

Is there any damage to the

rear microphone cable or
any connectors?
 Check Result Action Code Commodity
Replace the rear microphone
cable.
INTERNAL
Yes X03
CABLE
Determine whether the Verify that the issue is resolved.
damage is rear microphone
cable, the logic board, the
rear microphone board, or a
combination of multiple
7.
components.
ESCALATION REQUIRED.
No X99
Is the damage limited to the Contact ACS for additional
rear microphone cable only? support or a multiple-part repair.

Reseat camera/front Go to step 13.

Yes ${nodeText.yesSymptomCode}
microphone/ALS cable
securely to logic board and
camera.

Reseat rear microphone

cable securely to logic board
and rear microphone board.

Retest by going to System

Preferences > Sound > Input
tab, and verifying that the
input level indicator moves
when speaking into the
8. microphone.
Go to step 9.
No ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting with
the display panel removed.

Is the microphone
recognized and functional?
To troubleshoot this issue Go to step 10.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
camera/front
microphone/ALS cable is
required. Replace camera/front
9. microphone/ALS cable.
INTERNAL
No X03
CABLE
Do you have immediate Verify that the issue is resolved.
access to a known-good
camera/front
microphone/ALS cable?
Substitute a known-good Replace camera/front
camera/front microphone/ALS cable.
INTERNAL
microphone/ALS cable and Yes X03
CABLE
retest. Verify that the issue is resolved.
10.

Go to step 11.
Is the microphone No ${nodeText.noSymptomCode}
recognized and functional?
 Check Result Action Code Commodity
To troubleshoot this issue Go to step 12.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
rear microphone cable is
required.
Replace rear microphone cable.
11.
INTERNAL
No X03
Verify that the issue is resolved. CABLE
Do you have immediate
access to a known-good rear
microphone cable?
Substitute a known-good Replace rear microphone cable.
rear microphone cable and INTERNAL
Yes X03
retest. Verify that the issue is resolved. CABLE
12.
Go to step 13.
Is the microphone No ${nodeText.noSymptomCode}
recognized and functional?
Run AST 2 Audio Test to The issue was resolved by
verify that built-in reseating microphone cables.
Yes ${nodeText.yesSymptomCode}
microphones detect Verify resolution.
expected audio test patterns
produced from each
speaker.
13.
Refer to article TP587: Using
Go to step 14.
Audio Test. No ${nodeText.noSymptomCode}

Does unit pass AST 2 Audio

Test?
Go to step 15.
Front ${nodeText.yesSymptomCode}

Determine which component

failed the diagnostic test:
rear microphones or front ESCALATION REQUIRED.
microphones.
Rear microphones are part of
If the speaker tests failed, rear enclosure. Replace rear
then return to the list of enclosure. Verify issue resolved.
symptoms and select “No
14. Rear cover replacement is not
Audio from Internal
Rear normally covered by Apple’s ${nodeText.noSymptomCode}
Speakers or Headphone
Jack” from the one-year limited warranty or the
troubleshooting menu. AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.
Which microphones failed
the audio test? If the microphone issue was not
caused by accidental damage,
then contact ACS for additional
support regarding warranty
coverage for this part.

Front microphones are part Go to step 16.

Yes ${nodeText.yesSymptomCode}
of the display panel in this
model.

To troubleshoot this issue

Replace display panel, which
completely, a known-good
15. includes the front microphones.
display panel is required.
No L11 LCD
Verify issue resolved.
Do you have immediate
access to a known-good
display panel?
 Check Result Action Code Commodity
Replace display panel, which
includes the front microphones.
Yes L11 LCD
Verify issue resolved.
Substitute a known-good
display panel and retest. Replace logic board.
16.
Use Blank Board Serializer
Is camera working normally? (BBS) to set the computer’s
No M09 MLB
serial number.

Verify that the issue is resolved.

Verify that the “Internal Issue resolved.

Yes ${nodeText.yesSymptomCode}
microphone” device is
available, selected, and
functional, and that the input
level indicator moves when
speaking into the
microphone. Then record a
sample audio file and play it
back to verify that it is free of
17. ESCALATION REQUIRED.
distortion.
No M99
Run AST 2 Full System Contact ACS for additional
Diagnostic (EFI & OS), if support or a multiple-part repair.
available, to ensure no other
issues remain.

Is issue resolved?
No Audio from Internal Speaker(s) or Headphone Jack
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, DisplayPort cable, fan, hard disk drive (HDD), hard drive
data or power or combo cable, display panel, memory, power supply, solid state drive (SSD)/flash storage card, stand, Wi-
Fi/Bluetooth antennas, wireless card

Quick Check

Symptoms Quick Check

1. Adjust volume controls to verify setting is above
minimum, and audio is not muted.
2. Test with known-good stereo sound file.
3. Check that nothing is inserted into external audio port.
Use an otoscope to visually inspect the port. Use
compressed air to clean and remove any debris.
4. Connect headphones or external speakers to external
audio port. Verify in System Preferences > Sound >
Output that Audio Out setting switches to Headphones,
and whether audio can be played on external speakers.
5. Disconnect any device connected to external audio port.
In System Preferences > Sound > Output, check that
sound output device reverts to Internal Speakers. Use
Balance slider to isolate left and right speakers and
check whether issue is limited to one speaker.
6. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
7. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer versions to
make sure system build is correct for this computer
No sound from internal speaker(s). model. Check for and apply the latest software and
No sound from left and/or right speaker channel. firmware updates.
No sound from headphone jack.
Warning: Be extremely careful when working inside the
Note: Inform user that computer failures due to accidental computer with power applied and the system energized. Avoid
damage are not covered. If applicable, discuss out-of- touching the logic board or power supply while the computer
warranty repair options. is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Start up computer using an Go to step 2.
Yes ${nodeText.yesSymptomCode}
up-to-date, bootable macOS
volume. See articles Reinstall macOS on the user's
HT201314: About macOS computer. Refer to HT204319:
Recovery and HT204319: Use the Mac operating system
Use the Mac operating that came with your Mac, or a
1. system that came with your compatible newer version to
Mac, or a compatible newer No check that the system build is ${nodeText.noSymptomCode}
version. correct for this computer model.
Check for and apply the latest
software and firmware updates.
Does the audio issue persist Verify resolution.
from a known-good OS?
Connect headphones or Go to step 7.
Yes ${nodeText.yesSymptomCode}
external speakers to
computer and retest. Adjust
volume setting to verify
audio out to
headphones/external
2.
speakers. Go to step 3.
No ${nodeText.noSymptomCode}

Can you hear audio through

headphones/external
speakers?
Turn off computer. Unplug Go to step 4.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding.

Remove display panel.

3.
Go to step 5.
Inspect audio cable to audio No ${nodeText.noSymptomCode}
I/O ports and its
corresponding connection on
logic board.

Did you find damage to

audio cable or logic board
connector?
Replace the logic board. Verify
Yes that the issue is resolved. M09 MLB

ESCALATION REQUIRED.

Determine whether damage Audio I/O ports are part of the

is on the logic board, audio rear enclosure. Replace the rear
cable, or both. enclosure. Verify issue resolved.
4.
No Inform user that failures due to ${nodeText.noSymptomCode}
Is the damage limited to accidental damage are not
logic board? covered by Apple’s one-year
limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.
 Check Result Action Code Commodity
To troubleshoot this issue Go to step 6.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
logic board is required.
5. Replace the logic board. Verify
No that the issue is resolved. M09 MLB
Do you have immediate
access to a known-good
logic board?
Replace the logic board. Verify
Yes that the issue is resolved. M09 MLB

ESCALATION REQUIRED.
Substitute known-good logic
board and retest. Audio I/O ports are part of the
rear enclosure. Replace the rear
6. enclosure. Verify issue resolved.
Can you hear audio through
No ${nodeText.noSymptomCode}
headphones/external Inform user that failures due to
speakers? accidental damage are not
covered by Apple’s one-year
limited warranty or the
AppleCare Protection Plan.
Refer to
www.apple.com/legal/warranty.

Contact ACS for additional

support regarding warranty
coverage for this part.

Run AST 1 or AST 2 Audio

Test to verify left and right
speakers produce expected
audio test patterns from
each speaker. Yes ESCALATION REQUIRED. X99
7.
Refer to article TP587: Using Contact ACS for additional
Audio Test. support or a multiple-part repair.

Go to step 8.
Does unit pass Audio Test? No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 9.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding.

Remove display panel.

Locate speaker connections

on logic board. Disconnect
and inspect both speaker
8. cable connectors and
Go to step 10.
corresponding connectors on No ${nodeText.noSymptomCode}
logic board for damage.

Reconnect the left and right

speakers to the logic board,
verifying that the
connections are all seated
properly.

Did you find damage to

speakers or logic board
connector?
Speakers are replaced as a
matched set. Replace speakers
with a matched-pair replacement
OTHER
Yes kit. X08
ELECTRIC
Determine whether damage Verify that the issue is resolved.
is on the logic board,
speakers, or both.
9.

Is the damage limited to

speaker(s)?
No ESCALATION REQUIRED. X99

Contact ACS for additional

support or a multiple-part repair.
 Check Result Action Code Commodity
With speaker connectors The issue was resolved by
reseated to logic board, reseating cables. Verify
Yes ${nodeText.yesSymptomCode}
verify you can hear audio resolution.
through internal speakers.

In System Preferences >

Sound > Output tab, adjust
Balance slider to check left
and right speaker channel
separation.

Play music with high and low

tones to check bass and
tweeter performance of left
and right speakers.
10.
Warning: HIGH VOLTAGE: Go to step 11.
No ${nodeText.noSymptomCode}
The power supply remains
energized whenever the
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting with
the display panel removed.

Do internal speakers present

full range of expected audio
performance?
To troubleshoot this issue Go to step 12.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
internal speaker set is
required.

Internal speakers are

specified to work as a
matched pair and must be Speakers are replaced as a
tested or replaced as matched set. Replace speakers
11. matched pairs. with a matched-pair replacement
OTHER
No kit. X08
ELECTRIC
Keep and identify your
known-good speakers from Verify that the issue is resolved.
one kit as a matched pair.

Do you have immediate

access to a known-good
speaker set?
 Check Result Action Code Commodity
Substitute a known-good Speakers are replaced as a
internal speaker set and matched set. Replace speakers
verify you can hear audio with a matched-pair replacement
OTHER
through internal speakers. Yes kit. X08
ELECTRIC
Retest using AST 1 or AST Verify that the issue is resolved.
2 Audio Test to verify left
and right speakers produce
expected audio test patterns
from each speaker.

Refer to article TP587: Using

Audio Test.
12.
Warning: HIGH VOLTAGE:
The power supply remains Replace the logic board. Verify
energized whenever the No that the issue is resolved. M09 MLB
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
when troubleshooting with
the display panel removed.

Does unit pass Audio Test?

Connect and disconnect The issue is resolved. Verify
headphones/external Yes resolution. ${nodeText.yesSymptomCode}
speakers. Verify that audio
can be played through both
external and internal
speakers, and that sound is
clear and free of distortion.
13.
Run ASD or AST 2 Full
No ESCALATION REQUIRED. X99
System Diagnostic (EFI &
OS), if available, to ensure
no other issues remain. Contact ACS for additional
support or a multiple-part repair.

Is the issue resolved?

No Audio to External Display Speakers
Unlikely causes:
Battery, camera, camera cable, fan, DisplayPort cable, hard disk drive (HDD), HDD combo cable, display panel, left speaker,
memory, power supply, rear enclosure, right speaker, flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check
 Symptoms Quick Check
1. Gather display type and model information from the
user.
2. Always use a known-good USB-C Digital AV Multiport
Adapter and known-good HDMI display equipped with
internal speaker(s) to verify the computer. Review article
HT201853: About Apple video adapters and cables to
help identify which adapters can be used with this
computer model.
3. In System Preferences > Sound > Output, select the
available DisplayPort, Thunderbolt, HDMI, or USB
output device type (the output name varies depending
on the display model).
4. On the HDMI display, verify that the correct input has
been selected.
5. Connect the video adapter to each USB-C connector on
the computer and retest each time, to isolate a possible
faulty USB-C port on the user’s computer.
6. Test the audio output using more than one application or
website.
7. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
8. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure system build is correct for this computer
model. Check for and apply the latest software and
firmware updates.
9. With the user’s USB-C Digital AV Multiport Adapter or
USB-C Digital AV VGA Adapter connected to the
Video but no audio to external display; audio works on computer, check for and apply the latest software and
internal speakers firmware updates.
10. Refer to the following articles to learn more about
Note: Inform user that computer failures due to accidental Thunderbolt connectivity in this computer:
damage are not covered. If applicable, discuss out-of-
warranty repair options. HT204154: About Thunderbolt ports and displays
HT202488: About Apple Thunderbolt cables and
adapters

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Connect the known-good display, Go to step 2.
Yes ${nodeText.yesSymptomCode}
HDMI cable, and USB-C Digital
AV Multiport Adapter to the
user's computer.

Check System Preferences >

Sound > Output for an available
DisplayPort output device type.
Select the available device type,
adjust the volume level on the
1. display, and play the audio file or
Go to step 3.
source. No ${nodeText.noSymptomCode}

Disconnect the USB-C plug, then

flip it over and reconnect to test
both orientations.

Can the external display audio be

selected and play audio in both
plug orientations?
The issue is
isolated to the
user’s display or
HDMI cable.
Inform the user of
findings and refer
Connect the known-good display to article
and HDMI cable to the user's Yes HT204388: ${nodeText.yesSymptomCode}
USB-C Digital AV Multiport Frequently asked
Adapter, then to the computer. questions about
using HDMI with
Check System Preferences > Mac computers
Sound > Output for an available for more
HDMI output device type. Select information.
the available device type, adjust
the volume level on the display, The issue is
2.
and play the audio file or source. isolated to the
user’s adapter.
Disconnect the USB-C plug, then
flip it over and reconnect to test Replace the
both orientations. user’s USB-C
Digital AV
Multiport Adapter
Can the external display audio be No EXTERNAL
or USB-C Digital X03
selected and play audio in both CABLE
AV VGA Adapter.
plug orientations?
If user has third-
party adapter,
refer to
manufacturer for
support.
 Check Result Action Code Commodity
Reinstall macOS
Start up the user’s computer on the user’s
using a known-good, up-to-date, computer. Refer
and bootable macOS volume. to HT204319:
Use the Mac
Connect the known-good display, operating system
HDMI cable, and USB-C Digital
that came with
AV Multiport Adapter to the
your Mac, or a
user's computer.
compatible newer
Check System Preferences > Yes version to check ${nodeText.yesSymptomCode}
3. Sound > Output for an available that the system
DisplayPort, HDMI, or USB build is correct for
Output device type. Select the this computer
available device type, adjust the model. Check for
output volume level, and play the and apply the
audio file or source. latest software
and firmware
updates. Verify
Can the external display audio be resolution.
selected and play audio from a
known-good OS? Go to step 4.
No ${nodeText.noSymptomCode}
Inspect all USB-C receptacles Go to step 5.
Yes ${nodeText.yesSymptomCode}
and rear enclosure openings on
the user’s computer for any
signs of deformation, damage, or
debris that may be blocking the
connection. Use compressed air
to clear any obstructions or Replace logic
debris. board.
4.
No M09 MLB
Important: Do not use any metal Verify that the
objects to clear debris or issue is resolved.
obstructions, as this can short the
connector and cause damage.

Is any USB-C port damaged?

Replace the rear
Inspect the opening on the rear enclosure.
enclosure for the USB-C
Yes X13 ENCLOSURE
receptacle. Determine whether Verify that the
the opening is misshapen or issue is resolved.
deformed, preventing proper
5.
insertion of the USB-C plugs. Replace logic
board.
No M24 MLB
Is the opening for the USB-C port Verify that the
damaged or deformed? issue is resolved.

The issue is
Play a known-good audio file or resolved. Verify
Yes ${nodeText.yesSymptomCode}
source and verify that the sound resolution.
output to display speakers is
functional.

Run AST 2 Full System

Diagnostic (EFI & OS), if
6.
available, to ensure no other ESCALATION
issues remain. REQUIRED.
No X99
Verify that the issue is resolved. Contact ACS for
additional support
or a multiple-part
Is issue resolved? repair.
No Video to External Display
Unlikely causes:
Battery, camera, camera cable, fan, DisplayPort cable, hard disk drive (HDD), HDD combo cable, display panel, left speaker,
memory, power supply, right speaker, flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check
 Symptoms Quick Check
1. Gather display type and model information from the
user.
2. Always use a known-good USB-C Digital AV Multiport
Adapter and known-good HDMI display equipped with
internal speaker(s) to verify the computer. Review article
HT201853: About Apple video adapters and cables to
help identify which adapters can be used with this
computer model.
3. Refer to article HT201177: Get help with video issues on
external displays connected to your Mac for common
causes of video issues.
4. On the HDMI display, verify that the correct input has
been selected.
5. Connect the video adapter to each USB-C connector on
the computer and retest each time, to isolate a possible
faulty USB-C port on the user’s computer.
6. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
7. Reset the SMC using the procedure for this computer in
article HT201295: How to reset the System
Management Controller (SMC) on your Mac. Retest for
external video issues.
8. Refer to HT204319: macOS versions and builds
included with Mac computers to make sure system build
is correct for this computer model. Check for and apply
the latest software and firmware updates.
9. With the user’s USB-C Digital AV Multiport Adapter or
External display is not detected when connected to USB-C Digital AV VGA Adapter connected to the
computer computer, check for and apply the latest software and
External display does not show any video firmware updates.
10. Refer to the following articles to learn more about
Note: Inform user that computer failures due to accidental Thunderbolt connectivity in this computer:
damage are not covered. If applicable, discuss out-of-
warranty repair options. HT204154: About Thunderbolt ports and displays
HT202488: About Apple Thunderbolt cables and
adapters

Warning: Be extremely careful when working inside the

computer with power applied and the system is energized.
Avoid touching the logic board or power supply while the
computer is plugged in. Always cover the power supply and
logic board with Power Supply Covers to protect yourself
when working inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Connect the known-good display, Go to step 2.
Yes ${nodeText.yesSymptomCode}
HDMI cable, and USB-C Digital
AV Multiport Adapter to the
user’s computer.

Check System Preferences >

Displays for an available external
HDMI display type. Select the
available device type.

Verify that the external display

1. can be selected and that a good
Go to step 3.
image appears on the external No ${nodeText.noSymptomCode}
display.

Disconnect the USB-C plug, then

flip it over and reconnect to test
both orientations.

Does a good image appear on

the external display in both plug
orientations?
The issue is
isolated to the
user’s display or
HDMI cable.
Connect the known-good display Inform the user of
and HDMI cable to the user’s findings and refer
USB-C Digital AV Multiport to article
Yes HT204388: Mac ${nodeText.yesSymptomCode}
Adapter, then to the computer.
computers:
Check System Preferences > Frequently asked
Displays for an available external questions about
HDMI display type. Select the using HDMI for
available device type. more information.

Verify that the external display The issue is

2. can be selected and that a good isolated to the
image appears on the external user’s adapter.
display.
Replace the
Disconnect the USB-C plug, then user’s USB-C
flip it over and reconnect to test Digital AV
both orientations. Multiport Adapter
EXTERNAL
No or USB-C Digital X03
CABLE
AV VGA Adapter.
Does a good image appear on
the external display in both plug If user has third-
orientations? party adapter,
refer to
manufacturer for
support.
 Check Result Action Code Commodity
Start up the user’s computer Reinstall macOS
using a known-good, up-to-date, on the user’s
and bootable macOS volume. computer. Refer
to HT204319:
Connect the known-good display, Use the Mac
HDMI cable, and USB-C Digital operating system
AV Multiport Adapter to the that came with
user’s computer. your Mac, or a
compatible newer
Check System Preferences > version to check ${nodeText.yesSymptomCode}
Yes
Displays for an available external that the system
3.
HDMI display type. Select the build is correct for
available device type. this computer
model. Check for
Verify that the external display and apply the
can be selected and that a good latest software
image appears on the external and firmware
display. updates. Verify
resolution.

Does a good image appear on Go to step 4.

the external display? No ${nodeText.noSymptomCode}
Inspect all USB-C receptacles Go to step 5.
Yes ${nodeText.yesSymptomCode}
and rear enclosure openings on
the user’s computer for any
signs of deformation, damage, or
debris that may be blocking the
connection. Use compressed air
to clear any obstructions or Replace logic
debris. board.
4.
No M26 MLB
Important: Do not use any metal Verify that the
objects to clear debris or issue is resolved.
obstructions, as this can short the
connector and cause damage.

Is any USB-C port damaged?

Replace the rear
Inspect the opening on the rear enclosure.
enclosure for the USB-C
Yes X13 ENCLOSURE
receptacle. Determine whether Verify that the
the opening is misshapen or issue is resolved.
deformed, preventing proper
5.
insertion of the USB-C plugs. Replace logic
board.
No M24 MLB
Is the opening for the USB-C port Verify that the
damaged or deformed? issue is resolved.

The issue is
Restart the computer and verify Yes resolved. Verify
${nodeText.yesSymptomCode}
that a known-good external resolution.
display works over both VGA and
digital AV adapters.

Run AST 2 Full System

Diagnostic (EFI & OS), if
6.
available, to ensure no other ESCALATION
issues remain. REQUIRED.
No M99
Verify that the issue is resolved. Contact ACS for
additional support
or a multiple-part
Is issue resolved? repair.
USB Port Not Recognized
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, DisplayPort cable, hard disk drive (HDD), hard drive
data or power or combo cable, display panel, left speaker, memory, power supply, rear enclosure, right speaker, solid-state
drive (SSD)/flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check

Symptoms Quick Check

1. Disconnect all USB devices.
2. Verify that the user’s USB device is compatible with the
computer. Refer to HT201163: Using USB devices with
your Mac for more information about compatibility with
various USB devices.
3. Verify that any USB hubs connected to the computer
have sufficient power for a connected USB device.
4. Check to see whether the user’s USB device requires a
specific driver to function properly.
5. Check System Information > USB device tree to see
Standard USB devices not recognized or not powered.
whether the computer recognizes internal USB devices
(Bluetooth, IR, camera).
Note: Inform user that computer failures due to accidental
6. Reset the NVRAM using the procedure for this computer
damage are not covered. If applicable, discuss out-of- in article HT204063: How to Reset NVRAM on your Mac.
warranty repair options.
7. Reset the SMC using the procedure for this computer in
article HT201295: How to reset the System
Management Controller (SMC) on your Mac.
8. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure the system build is correct for this computer
model. Check for and apply the latest software and
firmware updates.
9. Test each USB port using a known-good Apple wired
keyboard or mouse.

Deep Dive

Check Result Action Code Commodity

Inspect USB ports for lint, Issue resolved.
debris, or other foreign Return computer to
material. Remove debris with user, explaining that
an anti-static brush. debris in USB port
Yes caused issue and ${nodeText.yesSymptomCode}
Important: Do not use any what to do to prevent
metal objects to clear debris or contamination in the
1. obstructions, as this can short future.
the connector and cause
damage.

Go to step 2.
No ${nodeText.noSymptomCode}
Is known-good Apple USB
device functional and
recognized?
Inspect all USB receptacles Go to step 3.
Yes ${nodeText.yesSymptomCode}
and rear enclosure openings on
the user’s computer for any
signs of deformation, damage,
2. or debris that may be blocking
Go to step 4.
the connection. No ${nodeText.noSymptomCode}

Is any USB port damaged?

 Check Result Action Code Commodity
Replace the rear
Inspect the opening on the rear
enclosure.
enclosure for the USB
receptacle. Determine whether Yes X13 ENCLOSURE
Verify that the issue
the opening is misshapen or
is resolved.
deformed, preventing proper
3.
insertion of the USB plugs.
Replace logic board.

No Verify that the issue M24 MLB

Is the opening for the USB port
is resolved.
damaged or deformed?
Disconnect all USB devices. Go to step 7.
Yes ${nodeText.yesSymptomCode}
Verify whether known-good
Apple wired keyboard or mouse
functions correctly and is
recognized in System
4. Information > USB device tree.
Go to step 5.
No ${nodeText.noSymptomCode}

Is known-good Apple USB

device functional and
recognized?
Continue to use known-good Go to step 6.
Yes ${nodeText.yesSymptomCode}
Apple wired keyboard or
mouse. Start up computer
using known-good, up-to-date,
bootable macOS volume. Verify
whether known-good USB
Replace logic board.
device functions correctly and
5.
is recognized in System
No Verify that the issue M15 MLB
Information > USB device tree.
is resolved.

Is a known-good Apple USB

device functional and
recognized?
Issue resolved by
directory repair in
Yes Disk Utility. Verify ${nodeText.yesSymptomCode}
resolution.

Use Disk Utility to repair the file Reinstall macOS on

directory on internal hard drive. the user’s computer.
Restart and verify whether a Refer to HT204319:
known-good USB device Use the Mac
functions correctly and is operating system that
recognized in System came with your Mac,
6.
Information > USB device tree. or a compatible
newer version to
No check that the system ${nodeText.noSymptomCode}
Is known-good Apple USB build is correct for this
device functional and computer model.
recognized? Check for and apply
the latest software
and firmware
updates. Verify
resolution.
 Check Result Action Code Commodity
This computer can support one Go to step 8.
Yes ${nodeText.yesSymptomCode}
high-powered USB device
(iPad, iPhone, or USB hard
drive for example) at a time.

Note: The first USB device to

draw more than 900 mA is
allotted up to 1100 mA, while
all subsequent devices are
7. limited to 900 mA. See article
Go to step 10.
HT204377: Powering No ${nodeText.noSymptomCode}
peripherals through USB for
more information.

Do you have immediate access

to a known-good, high-powered
USB device that draws over
900 mA?
Connect known-good, high- Go to step 9.
Yes ${nodeText.yesSymptomCode}
powered USB device to one of
the computer’s USB ports. In
System Information > USB
device tree, “Current Available
(mA)” and “Extra Operating
Current (mA)” should each
report 900 mA.

Note: The first USB device to

8. draw more than 900 mA is Replace logic board.
allotted up to 1100 mA, while No Verify issue resolved. M38 MLB
all subsequent devices are
limited to 900 mA. Verify that
known-good USB device
functions as expected.

Does “Extra Operating

Current” appear in System
Information?
Connect exact same high- Go to step 10.
Yes ${nodeText.yesSymptomCode}
powered USB device to next
USB port. Make sure nothing is
plugged into other port(s). Both
“Current Available (mA)” and
“Extra Operating Current
(mA)” should each report 900
mA in System Information.
Repeat action with every
available USB port.
9. Replace logic board.
Note: The first USB device to
No Verify issue resolved. M38 MLB
draw more than 900 mA is
allotted up to 1100 mA, while
all subsequent devices are
limited to 900 mA. Verify USB
device operates as expected.

Does “Extra Operating

Current” appear in System
Information?
 Check Result Action Code Commodity
Issue resolved by
testing USB ports and
verifying user’s USB
Yes ${nodeText.yesSymptomCode}
device. Verify
resolution.

Advise user to do the

Try user’s USB device with a following:
known-good computer. Verify
whether it functions normally Contact USB
and is recognized in System device
10. Information > USB device tree. manufacturer
for support.
Verify system
Is user’s USB device No requirements ${nodeText.noSymptomCode}
functional and recognized? and Mac
compatibility.
Find out
whether device
requires
additional
software.

Confirm that a known-good Issue resolved.

Yes ${nodeText.yesSymptomCode}
USB device is functional and
recognized.

Check System Information for

correct power allocation to USB
device.

Run ASD or AST 2 Full System

11. ESCALATION
Diagnostic (EFI & OS), if
No REQUIRED. M99
available, to ensure no other
issues remain.
Contact ACS for
Verify that the issue is additional support or
resolved. a multiple-part repair.

Is issue resolved?
USB-C and Thunderbolt Connectivity Issues
Unlikely causes:
Battery, camera, camera cable, fan, DisplayPort cable, hard disk drive (HDD), HDD combo cable, display panel, left speaker,
memory, power supply, right speaker, flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check
 Symptoms Quick Check
1. Verify that any USB hubs connected to the computer
have sufficient power for a connected USB device.
2. Check whether the user’s USB device requires a
specific driver to function properly.
3. If the user is using a USB 3 device, review article
HT201163: Using USB 3 devices with Mac computers.
4. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
5. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Controller (SMC) on your Mac to return computer to a
known power-off state. Try to turn on from power-off
state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
into DFU mode if you do. Retest for USB-C connectivity
issues.
6. Refer to HT201260: How to find the macOS version
number on your Mac to check that the system build is
correct for this computer model.
7. Using a Wi-Fi network, check for and apply the latest
software and firmware updates. Also check for adapter
firmware updates by leaving the user’s adapter
connected to the computer while running software
update. If an update is available, update the adapter’s
firmware before proceeding further, and retest for USB-
C connectivity issues.
Standard USB-C devices are not recognized or not 8. Refer to the following articles to learn more about
powered when connected to computer's USB-C port(s). Thunderbolt connectivity in this computer:
USB 2 or USB 3 devices are not recognized or not
powered when connected to computer's USB-C port(s). HT207256: Connect with Thunderbolt 3 on your new
External DisplayPort or Thunderbolt devices or displays MacBook Pro
are not recognized when connected to computer's USB- HT204360: Using USB-C and Thunderbolt 3 (USB-C)
C port(s). ports and adapters on your Mac notebook
HT204154: About Thunderbolt ports and displays
Note: Inform user that computer failures due to accidental HT206909: Networking two Mac systems directly with a
damage are not covered. If applicable, discuss out-of- Thunderbolt 3 cable requires Thunderbolt-enabled hosts
warranty repair options. HT207113: How to daisy-chain USB 2.0 devices to
Thunderbolt 3 ports

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017) refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Inspect all USB-C receptacles Go to step 2.
Yes ${nodeText.yesSymptomCode}
and rear enclosure openings on
the user’s computer for any
signs of deformation, damage,
or debris that may be blocking
the connection. Use compressed
air to clear any obstructions or
debris.
1.
Go to step 3.
Important: Do not use any No ${nodeText.noSymptomCode}
metal objects to clear debris or
obstructions, as this can short
the connector and cause
damage.

Is any USB-C port damaged?

Replace the rear
enclosure.
Yes X13 ENCLOSURE
Verify that the
Inspect the opening on the rear issue is resolved.
enclosure for the USB-C
receptacle. Determine whether Replace logic
the opening is misshapen or board.
deformed, preventing proper
2.
insertion of the USB-C plugs. Use Blank Board
Serializer (BBS)
to set the
No M24 MLB
Is the opening for the USB-C computer’s serial
port damaged or deformed? number.

Verify that the

issue is resolved.

Using a known-good Apple Go to step 4.

Yes ${nodeText.yesSymptomCode}
USB-C to USB Adapter, connect
a known-good high-speed USB Replace logic
(1.1/2.0) device, such as a board.
mouse, keyboard, or USB 2
flash drive to the same USB-C Use Blank Board
port on the computer. Serializer (BBS)
3.
to set the
No M15 MLB
Verify in System Information > computer’s serial
USB that the device is detected. number.

Verify that the

Is the USB 1.1/2.0 device issue is resolved.
detected?
Disconnect and flip the Go to step 5.
Yes ${nodeText.yesSymptomCode}
orientation of the USB-C Apple
adapter cable plug, then
reconnect it to the same USB-C
port on the computer and retest,
Replace logic
to test both orientations.
board.
Refresh the USB Device Tree in
Use Blank Board
System Information by using the
Serializer (BBS)
4. Command-R keyboard shortcut,
to set the
or the File > Refresh Information No M15 MLB
computer’s serial
from the menu bar.
number.
Verify in System Information >
Verify that the
USB that the device is detected.
issue is resolved.

Is the USB 1.1/2.0 device

detected?
 Check Result Action Code Commodity
Go to step 6.
Yes ${nodeText.yesSymptomCode}
Using a known-good Apple
USB-C to USB Adapter, connect Replace logic
a known-good USB 3 device, board.
such as a USB 3 hard drive or
flash drive to the same USB-C Use Blank Board
port on the computer. Serializer (BBS)
5.
to set the
No M15 MLB
Verify in System Information > computer’s serial
USB that the device is detected. number.

Verify that the

Is the USB 3 device detected? issue is resolved.

Disconnect and flip the Go to step 7.

Yes ${nodeText.yesSymptomCode}
orientation of the USB-C Apple
adapter cable plug, then
reconnect it to the same USB-C
port on the computer and retest, Replace logic
to test both orientations. board.

Refresh the USB Device Tree in Use Blank Board

System Information by using the Serializer (BBS)
6.
Command-R keyboard shortcut, to set the
No M15 MLB
or the File > Refresh Information computer’s serial
from the menu bar. number.

Verify in System Information > Verify that the

USB that the device is detected. issue is resolved.

Is the USB 3 device detected?

Using the user’s Apple USB-C Go to step 8.
Yes ${nodeText.yesSymptomCode}
to USB Adapter in place of the
known-good adapter, connect a
known-good USB 3 device, such
as a USB 3 hard drive or flash
drive to the same USB-C port on
the computer.

Refer to HT204360: Using USB- Replace the

C and Thunderbolt 3 (USB-C) user’s Apple
USB-C adapter.
ports and adapters on your Mac
notebook for more information
If the adapter is
about Apple USB-C adapters. made by a third
7.
party, advise the EXTERNAL
Refresh the USB Device Tree in No user to contact the
X03
CABLE
System Information by using the manufacturer for
Command-R keyboard shortcut, support.
or the File > Refresh Information
from the menu bar.
Verify that the
issue is resolved.
Verify in System Information >
USB that the device is detected.

Be sure to test both orientations.

Is the USB 3 device detected?

 Check Result Action Code Commodity
Using a known-good Apple Go to step 9.
Yes ${nodeText.yesSymptomCode}
Thunderbolt 3 (USB-C) to
Thunderbolt 2 Adapter, connect
a known-good external
Thunderbolt 2 device such as a
display or external disk to the
same USB-C port on the Replace logic
computer. board.

Verify in System Information > Use Blank Board

Thunderbolt that the device is Serializer (BBS)
8. detected. to set the
No M33 MLB
computer’s serial
Refer to HT207266: Connect number.
devices and displays with the
Apple Thunderbolt 3 (USB-C) to Verify that the
Thunderbolt 2 Adapter for more issue is resolved.
information about this adapter.

Is the Thunderbolt 2 device

detected?
Disconnect and flip the Go to step 10.
Yes ${nodeText.yesSymptomCode}
orientation of the USB-C Apple
adapter cable plug, then
reconnect it to the same USB-C
port on the computer and retest,
to test both orientations. Replace logic
board.
Refresh the USB Device Tree in
System Information by using the Use Blank Board
Command-R keyboard shortcut, Serializer (BBS)
9.
or the File > Refresh Information to set the
No M33 MLB
from the menu bar. computer’s serial
number.
Verify in System Information >
Thunderbolt that the device is Verify that the
detected. issue is resolved.

Is the Thunderbolt 2 device

detected?
 Check Result Action Code Commodity
Using the user’s Apple Go to “No Video
Thunderbolt 3 (USB-C) to on External
Thunderbolt 2 Adapter in place Display”
Yes ${nodeText.yesSymptomCode}
of the known-good adapter, troubleshooting
connect a known-good external flow.
Thunderbolt 2 device such as a
display or external disk to the
same USB-C port on the
computer.

Refer to HT204360: Using USB-

C and Thunderbolt 3 (USB-C)
Replace the
ports and adapters on your Mac
user’s Apple
notebook for more information
USB-C adapter.
about Apple USB-C adapters.
10.
If the adapter is
Refresh the USB Device Tree in
made by a third
System Information by using the party, advise the EXTERNAL
Command-R keyboard shortcut, No user to contact the
X03
CABLE
or the File > Refresh Information manufacturer for
from the menu bar. support.
Verify in System Information > Verify that the
Thunderbolt that the device is issue is resolved.
detected.

Be sure to test both orientations.

Is the Thunderbolt 2 device

detected?
Confirm that known-good USB The issue is
high-speed and SuperSpeed resolved. Verify
Yes ${nodeText.yesSymptomCode}
devices and Thunderbolt resolution.
devices are functional and
recognized when connected to
all USB-C ports on the
computer, in both orientations.

11. Run AST 2 Full System

Diagnostic (EFI & OS), if ESCALATION
available, to ensure no other No REQUIRED. X99
issues remain.
Contact ACS for
Verify that the issue is resolved. additional support
or a multiple-part
repair.
Is the issue resolved?
External USB ODD Noisy
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Verify that the user’s issue involves only abnormal
sounds, as defined in symptoms.
2. Make sure the Apple USB SuperDrive is sitting flat on a
surface with the silver top facing upward. Do not attempt
to operate the SuperDrive on its side or upside-down.
3. Verify that there is not an additional label adhered to the
disc which could cause the disc to lose balance and
create excessive noise when rotating at high speed.
4. Verify that the optical drive is actually an Apple USB
Note: Be sure you understand what type of optical drive noise SuperDrive, which has a longer USB cable (340 mm),
you should be concerned about and what noises you can and not a MacBook Air SuperDrive, which has a slightly
safely ignore. The following lists help distinguish normal, shorter cable (250 mm) that may not reach iMac’s USB
functional optical drive sounds from noises that may indicate ports while sitting on a flat surface alongside iMac.
drive malfunction. 5. Compare optical drive noise to a known-good equivalent
Apple USB SuperDrive.
Typical noises include sounds made during the following 6. Verify that the noise issue does not involve waking the
activities: computer. When starting up or waking from sleep, the
Apple USB SuperDrive may make unfamiliar noises.
Waking computer from sleep 7. Test the user’s optical disc in a known-good drive to
Burning a CD or DVD rule out a media issue. Verify disc size and shape are
Inserting a disc within specification in article HT201788: Get help with
Ejecting a disc the slot-loading SuperDrive on your Mac computer.
Importing (“ripping”) an audio CD in iTunes 8. Test Apple USB SuperDrive with known-good discs.
Playing a DVD Verify media is free to spin without scraping edge or
Accessing an idle disc surface of media.
9. Verify noise during seek activity is excessive. Seek
Abnormal noises include the following: noise should subside once disc is mounted.
10. Verify disc spin noise is excessive. Disc spin should
Grinding cease 30 seconds after mounting disc in Finder.
Loud, repeated clicking 11. Inspect the Apple USB SuperDrive drive slot for
Scraping sounds obstructions such as debris or a stuck disc.
Constantly seeking or cycling the eject mechanism with 12. Inspect the Apple USB SuperDrive USB cable and USB
no disc inserted connector for damage.
13. The Apple USB SuperDrive is designed exclusively for
Listen closely in a quiet environment for the following: use with iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, and Mac mini (Early 2009 or later). USB
Noise during start up ports on other computers may not provide sufficient
Noise during operation power to enable proper operation of drive. Verify user’s
Noise when drive is copying or saving data configuration is supported.
14. The Apple USB SuperDrive must be plugged directly
Note: Inform user that computer failures due to accidental into computer’s USB port, and cannot be used while
damage are not covered. If applicable, discuss out-of- connected to a USB hub.
warranty repair options. 15. Leave the Apple USB SuperDrive connected to the
user's computer and restart the computer while pressing
the mouse button or keyboard Eject key to cycle the
optical drive.
16. If the user is experiencing an issue using the Apple USB
SuperDrive with Microsoft Windows, try starting the
computer with the Apple USB SuperDrive already
plugged in.
17. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.

Deep Dive
 Check Result Action Code Commodity
Check whether the Apple USB Replace the Apple USB
SuperDrive is constantly SuperDrive. Verify issue
Yes J04 OPTICAL
seeking or cycling eject resolved.
mechanism with no optical disc
inserted. Optical drive should
perform only one reset
sequence and then rest idly,
1.
ready for media.
Go to step 2.
No ${nodeText.noSymptomCode}
Does the optical drive spin,
seek, and/or reset continuously
without an optical disc
inserted?
Closely inspect the user's Go to step 3.
Yes ${nodeText.yesSymptomCode}
Apple USB SuperDrive to
determine whether a disc or
other debris is stuck inside.
2.
Go to step 4.
No ${nodeText.noSymptomCode}
Is a disc or other debris stuck
in drive?
Refer to RP451: Apple USB Issue resolved by
SuperDrive to open the drive removing stuck disc or
enclosure and remove any Yes debris from drive. Verify ${nodeText.yesSymptomCode}
stuck disc, dust, debris, or resolution.
other foreign materials.

3. Retest the Apple USB

SuperDrive by inserting,
Replace the Apple USB
mounting, and ejecting a
SuperDrive. Verify issue
known-good optical disc. No J05 OPTICAL
resolved.

Is optical drive function fully

restored?
Insert a known-good optical Replace the Apple USB
disc, then eject the disc. Listen SuperDrive. Verify issue
Yes J04 OPTICAL
carefully to Apple USB resolved.
SuperDrive disc handling. Eject
noise should consist of a pop
as disc is released from motor
hub, then gear movement as
4.
motor pushes disc out of slot.
Repeat test several times. Go to step 5.
No ${nodeText.noSymptomCode}

Is disc eject noise abnormal

and excessive over multiple
trials?
Disconnect the Apple USB Go to step 6.
Yes ${nodeText.yesSymptomCode}
SuperDrive and retest for
computer noise. Go to
5.
“Noise/Hum/Vibration”
No ${nodeText.noSymptomCode}
troubleshooting flow.
Has the noise been eliminated?
To troubleshoot this issue Go to step 7.
Yes ${nodeText.yesSymptomCode}
completely, you will need an
identical, known-good Apple
USB SuperDrive with which to
compare optical drive sounds. Replace the Apple USB
6.
SuperDrive. Verify issue
No J04 OPTICAL
resolved.
Do you have immediate access
to a known-good Apple USB
SuperDrive?
 Check Result Action Code Commodity
Replace the Apple USB
SuperDrive. Verify issue
Substitute a known-good Apple Yes J04 OPTICAL
resolved.
USB SuperDrive and retest.
7.
Go to
“Noise/Hum/Vibration”
Has the noise been eliminated? No ${nodeText.noSymptomCode}
troubleshooting flow.

Verify that the Apple USB Issue resolved.

Yes ${nodeText.yesSymptomCode}
SuperDrive does not make any
abnormal noises. Go to
8.
“Noise/Hum/Vibration”
No ${nodeText.noSymptomCode}
troubleshooting flow.
Is the issue resolved?
External USB ODD Not Recognized
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Go to Finder Preferences > General and make sure
“CDs, DVDs, and iPods” is checked under “Show
these items on the desktop.”
2. Make sure the Apple USB SuperDrive is sitting flat on a
surface with the silver top facing upward. Do not attempt
to operate the SuperDrive on its side or upside-down.
3. Verify that the optical drive is actually an Apple USB
SuperDrive, which has a longer USB cable (340 mm),
and not a MacBook Air SuperDrive, which has a slightly
shorter cable (250 mm) that may not reach iMac’s USB
ports while sitting on a flat surface alongside iMac.
4. Inspect the Apple USB SuperDrive drive slot for
obstructions (stuck disc, for example)
5. Inspect the Apple USB SuperDrive USB cable and USB
connector for damage.
6. The Apple USB SuperDrive is designed exclusively for
use with iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, and Mac mini (Early 2009 or later). USB
Discs cannot be inserted. ports on other computers may not provide sufficient
Discs can be inserted, but are ejected immediately. power to enable proper operation of drive. Verify user’s
Discs can be inserted, but are ejected after drive has configuration is supported.
spun up for a few seconds. 7. The Apple USB SuperDrive must be plugged directly
Discs can be inserted and ejected, but do not appear in into the computer’s USB port, and cannot be used while
Finder. connected to a USB hub.
8. Leave the Apple USB SuperDrive connected to the
Note: Inform user that computer failures due to accidental user's computer and restart the computer while pressing
damage are not covered. If applicable, discuss out-of- the mouse button or keyboard Eject key to cycle the
warranty repair options. optical drive.
9. If the user is experiencing an issue using the Apple USB
SuperDrive with Microsoft Windows, try starting the
computer with the Apple USB SuperDrive already
plugged in.
10. Refer to article HT201788: Get help with the slot-loading
SuperDrive on your Mac computer.
11. Connect the user’s Apple USB SuperDrive to a known-
good iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, or Mac mini (Early 2009 or later) to verify
drive’s functionality separately from user’s computer.
12. Disconnect the user’s Apple USB SuperDrive and
connect a known-good Apple USB SuperDrive to the
same USB port on the user’s computer to verify the
computer’s functionality separately from the user’s
drive. If the issue persists, troubleshoot as a faulty USB
port on the user’s computer.
13. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.

Deep Dive
 Check Result Action Code Commodity
Connect the user's Apple USB Go to step 2.
Yes ${nodeText.yesSymptomCode}
SuperDrive to an available USB
port on user's computer and start
up the computer. Check System
Information > Hardware > USB
device tree to verify the presence
of the optical drive.
Go to “USB Port
1. Repeat this process using each Not Recognized"
USB port on the user's computer No troubleshooting ${nodeText.noSymptomCode}
to verify all of the computer's USB flow.
ports are functioning.

Does drive appear in System

Information when connected to
every USB port?
Attempt to insert a known-good, Replace the Apple
properly formatted CD or DVD USB SuperDrive.
disc into the Apple USB Yes Verify issue J01 OPTICAL
SuperDrive. Check whether the resolved.
disc auto-ejects either
immediately or within a few
2.
seconds after the drive has spun
up.
Go to step 3.
No ${nodeText.noSymptomCode}

Does disc auto-eject shortly after

insertion?
After insertion, verify that the disc Go to step 4.
Yes ${nodeText.yesSymptomCode}
spins and the disc volume mounts
in the Finder. Replace the Apple
3. USB SuperDrive.
No Verify issue J09 OPTICAL
Does drive mount known-good resolved.
disc?
Check to see whether the Apple Issue resolved.
Yes ${nodeText.yesSymptomCode}
USB SuperDrive properly mounts
and reads both known-good CD
Go to “External
and DVD media.
USB ODD
Read/Write or
4. If only one type of media is
Performance
recognized, there may be a laser No ${nodeText.noSymptomCode}
Issues”
issue.
troubleshooting
flow.
Can drive read both media types?
Issue resolved.
Yes ${nodeText.yesSymptomCode}

Insert, mount, and eject both a

known-good CD and DVD.
5. ESCALATION
No REQUIRED. J99
Is the issue resolved?
Contact ACS for
additional support
or a multiple-part
repair.
External USB ODD Read/Write or Performance Issues
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Test the user’s optical disc in a known-good drive to
rule out a media issue. Verify disc size and shape are
within specification in article HT201788: Get help with
the slot-loading SuperDrive on your Mac computer.
2. Test known-good, compatible optical media in user's
Apple USB SuperDrive connected to a known-good
computer.
3. Go to System Information > Hardware > Disc Burning to
compare actual disc burning specifications to user's
expectations.
4. See articles HT2543: About optical disc drive burning
and write speeds and HT2882: Factors that affect
writing to or reading from optical media to learn more
about disc burning and how performance is affected by
write speeds, media types, software, and more.
5. Make sure the Apple USB SuperDrive is sitting flat on a
surface with the silver top facing upward. Do not attempt
to operate the SuperDrive on its side or upside-down.
6. Verify that the optical drive is actually an Apple USB
SuperDrive, which has a longer USB cable (340 mm),
Errors when writing to optical media
Errors when reading from optical media and not a MacBook Air SuperDrive, which has a slightly
Hangs when accessing or writing data shorter cable (250 mm) that may not reach iMac’s USB
Read or write speeds slower than expected ports while sitting on a flat surface alongside iMac
7. Inspect the Apple USB SuperDrive drive slot for
obstructions (stuck disc, for example).
Note: Inform user that computer failures due to accidental
damage are not covered. If applicable, discuss out-of- 8. Inspect the Apple USB SuperDrive USB cable and USB
warranty repair options. connector for damage.
9. The Apple USB SuperDrive is designed exclusively for
use with iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, and Mac mini (Early 2009 or later). USB
ports on other computers may not provide sufficient
power to enable proper drive operation. Verify user’s
configuration is supported.
10. The Apple USB SuperDrive must be directly plugged
into into the computer’s USB port and cannot be used
while connected to a USB hub.
11. With the Apple USB SuperDrive connected to the
user’s computer, restart the computer while pressing
the mouse button or Eject key to cycle the optical drive.
12. If the user is experiencing an issue using the Apple USB
SuperDrive with Microsoft Windows, try starting the
computer with the Apple USB SuperDrive already
plugged in.
13. Refer to article HT201788: Get help with the slot-loading
SuperDrive on your Mac computer.
14. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.

Deep Dive
 Check Result Action Code Commodity
Connect the user’s Apple USB Go to step 2.
Yes ${nodeText.yesSymptomCode}
SuperDrive to an available USB
port on the user’s computer and
start up the computer. Insert
media into the Apple USB
SuperDrive and listen for
scraping/scratching noises as the
disc spins up. Eject the disc and Replace the Apple
1. examine its surface and edges USB SuperDrive.
for scrapes or scratches. Verify No Verify issue J05 OPTICAL
that the disc can spin without the resolved.
optical drive scraping the edge or
surface of the media.

Does media spin freely in the

drive?
Closely inspect the user's Apple Go to step 3.
Yes ${nodeText.yesSymptomCode}
USB SuperDrive to determine if a
disc or other debris is stuck
inside.
2.
Go to step 4.
No ${nodeText.noSymptomCode}
Is a disc or other debris stuck in
the drive?
Refer to RP451: Apple USB Issue resolved by
SuperDrive to open the drive removing stuck
enclosure and remove any stuck Yes disc or debris from
${nodeText.yesSymptomCode}
disc, dust, debris, or other foreign drive. Verify
materials. resolution.

3. Retest the Apple USB

SuperDrive by inserting,
Replace the Apple
mounting, and ejecting a known-
USB SuperDrive.
good optical disc.
No Verify issue J05 OPTICAL
resolved.
Is optical drive function fully
restored?
Verify that the optical drive can Go to step 5.
Yes ${nodeText.yesSymptomCode}
properly read known-good CDs.
4.
Go to step 6.
No ${nodeText.noSymptomCode}
Can the optical drive read CDs?
Verify that the optical drive can Go to step 7.
Yes ${nodeText.yesSymptomCode}
properly read known-good DVDs.
5.
Go to step 6.
No ${nodeText.noSymptomCode}
Can the optical drive read DVDs?
Go to step 7.
Check System Information > Yes ${nodeText.yesSymptomCode}
Hardware > USB to verify
Go to “External
presence of optical drive.
USB ODD Not
6.
Recognized”
No ${nodeText.noSymptomCode}
troubleshooting
Does the optical drive appear in
flow.
System Information?
Burn test data to CD and DVD Go to step 8.
Yes ${nodeText.yesSymptomCode}
media compatible with the Apple
USB SuperDrive. Verify that the
burned media is recognized and Replace the Apple
7. readable by the drive. USB SuperDrive.
No Verify issue J03 OPTICAL
resolved.
Can the optical drive read its own
burned media?
 Check Result Action Code Commodity
To troubleshoot this issue Go to step 9.
Yes ${nodeText.yesSymptomCode}
completely, you will need an
identical, known-good Apple USB
SuperDrive with which to
compare optical disc read and Replace the Apple
8. burn times. USB SuperDrive.
No Verify issue J07 OPTICAL
resolved.
Do you have immediate access
to a known-good Apple USB
SuperDrive?
Using the same media type and Replace the Apple
brand, compare read and burn USB SuperDrive.
times of the user's Apple USB Yes Verify issue J07 OPTICAL
SuperDrive connected to a resolved.
known-good computer, against a
known-good Apple USB
9. SuperDrive connected to the
same computer.
Issue resolved.
No ${nodeText.noSymptomCode}
Does the user's drive have
significantly longer read or burn
times than a known-good drive?
Issue resolved.
Yes ${nodeText.yesSymptomCode}

Test all Apple USB SuperDrive

functions and drive performance
to verify a successful repair. ESCALATION
10.
No REQUIRED. J99
Is the issue resolved? Contact ACS for
additional support
or a multiple-part
repair.
External USB ODD Rejects, Does Not Accept, or Does Not
Eject Media
Unlikely causes:

There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Test the user’s optical disc in a known-good drive to
rule out a media issue. Verify disc size and shape are
within specification in article HT201788: Get help with
the slot-loading SuperDrive on your Mac computer.
2. Connect the user’s Apple USB SuperDrive to a known-
good iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, or Mac mini (Early 2009 or later) to verify
drive’s functionality separately from user’s computer.
3. Disconnect the user’s Apple USB SuperDrive and
connect a known-good Apple USB SuperDrive to the
same USB port on the user’s computer to verify the
computer’s functionality separately from the user’s
drive. If the issue persists, troubleshoot as a faulty USB
port on the user’s computer.
4. Make sure the Apple USB SuperDrive is sitting flat on a
surface with the silver top facing upward. Do not attempt
to operate the SuperDrive on its side or upside-down.
5. Verify that optical drive is actually an Apple USB
SuperDrive, which has a longer USB cable, and not a
MacBook Air SuperDrive, which has a slightly shorter
Cannot insert a disc into drive. cable that may not reach iMac’s USB ports while sitting
Cannot eject a disc from drive. on a flat surface alongside the computer.
Drive ejects discs immediately after insertion. 6. Inspect the Apple USB SuperDrive drive slot for
obstructions (stuck disc, for example).
Note: Inform user that computer failures due to accidental 7. Inspect the Apple USB SuperDrive USB cable and USB
damage are not covered. If applicable, discuss out-of- connector for damage.
warranty repair options. 8. The Apple USB SuperDrive is designed exclusively for
use with iMac, MacBook Pro (Retina, Mid 2012 or later),
MacBook Air, and Mac mini (Early 2009 or later). USB
ports on other computers may not provide sufficient
power to enable proper operation of drive. Verify user's
configuration is supported.
9. The Apple USB SuperDrive must be plugged directly
into the computer’s USB port, and cannot be used while
connected to a USB hub.
10. Leave the Apple USB SuperDrive connected to the
user's computer and restart the computer while pressing
the mouse button or keyboard Eject key to cycle the
optical drive.
11. If the user is experiencing an issue using the Apple USB
SuperDrive with Microsoft Windows, try starting the
computer with the Apple USB SuperDrive already
plugged in.
12. Refer to article HT201788: Get help with the slot-loading
SuperDrive on your Mac computer.
13. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.

Deep Dive
 Check Result Action Code Commodity
Connect the user’s Apple USB Go to step 2.
Yes ${nodeText.yesSymptomCode}
SuperDrive to an available USB
port on the user’s computer and
start up the computer. Check
Go to “External
System Information > Hardware >
USB ODD Not
1. USB to verify presence of optical
Recognized”
drive. No ${nodeText.noSymptomCode}
troubleshooting
flow.
Does the optical drive appear in
System Information?
Closely inspect the user's Apple Go to step 13.
Yes ${nodeText.yesSymptomCode}
USB SuperDrive to determine if a
disc or other debris is stuck
inside.
2.
Go to step 3.
No ${nodeText.noSymptomCode}
Is a disc or other debris stuck in
drive?
Verify known-good disc can fit Go to step 5.
Yes ${nodeText.yesSymptomCode}
through enclosure slot.
3.
Go to step 4.
No ${nodeText.noSymptomCode}
Is clearance in enclosure slot
sufficient for disc insertion?
Closely inspect entire Apple USB Go to step 14.
Yes ${nodeText.yesSymptomCode}
SuperDrive enclosure for dents,
scratches, or other indications of
Replace the Apple
impact or abuse.
4. USB SuperDrive.
No Verify issue J01 OPTICAL
resolved.
Is insufficient clearance due to
accidental damage?
Inspect the slot on the optical Go to step 10.
Yes ${nodeText.yesSymptomCode}
drive assembly for proper disc
clearance.
5.
Go to step 6.
No ${nodeText.noSymptomCode}
Is clearance in optical drive slot
sufficient for disc insertion?
When a CD or DVD pops off the Go to step 14.
Yes ${nodeText.yesSymptomCode}
spindle inside an optical drive
(usually due to impact to the
drive) and remains in the drive
mechanism, the loose disc
prevents the slot from being able
to open fully, creating a “closed
condition.” Inspect the slot in the
optical drive to determine if it is
“closed” (not accepting discs).

If the disc slot is closed, inspect

6.
the drive mechanism, especially Go to step 7.
No ${nodeText.noSymptomCode}
the drive enclosure, for evidence
of drop damage.

Note: If the disc slot is closed,

but there is no sign of
accidental damage, choose
“No” to the question below.

Is disc slot access closed due to

accidental damage?
 Check Result Action Code Commodity
Inspect the slot in the Apple USB Go to step 13.
Yes ${nodeText.yesSymptomCode}
SuperDrive to determine if it is
“closed” (not accepting discs)
because of a stuck disc.
7.
Go to step 8.
No ${nodeText.noSymptomCode}
Is disc slot access closed
because of a stuck disc?
Make sure the optical drive Go to step 10.
Yes ${nodeText.yesSymptomCode}
assembly is mounted into the
enclosure correctly and is
properly aligned with the
enclosure slot opening.
8.
Go to step 9.
No ${nodeText.noSymptomCode}
Is the drive assembly properly
aligned with the enclosure slot
opening?
Refer to RP451: Apple USB Issue resolved.
SuperDrive to open the drive Apple USB
enclosure and align the optical SuperDrive
drive assembly with the alignment
enclosure's bezel slot. Yes realigned disc ${nodeText.yesSymptomCode}
inject function.
Retest the Apple USB Verify issue
9.
SuperDrive by inserting, resolved.
mounting and ejecting a known-
good optical disc. Replace the Apple
USB SuperDrive.
No Verify issue J01 OPTICAL
Is optical drive function fully resolved.
restored?
Attempt to insert a known-good, Replace the Apple
properly formatted CD or DVD USB SuperDrive.
disc into the Apple USB Yes Verify issue J01 OPTICAL
SuperDrive. Check whether the resolved.
disc auto-ejects either
immediately or within a few
10.
seconds after the drive has spun
up.
Go to step 11.
No ${nodeText.noSymptomCode}

Does the disc immediately auto-

eject?
Go to step 12.
Yes ${nodeText.yesSymptomCode}
After insertion, verify that the disc Go to “External
spins and the disc volume USB ODD
mounts in the Finder. Read/Write or
11.
Performance
No ${nodeText.noSymptomCode}
Issues”
Does the disc volume mount? troubleshooting
flow.

Eject the disc by dragging the Issue resolved.

Yes ${nodeText.yesSymptomCode}
disc icon to Trash or selecting the
disc icon and pressing the Eject
Replace the Apple
key or Command-E on the
12. USB SuperDrive.
keyboard.
No Verify issue J02 OPTICAL
resolved.
Does the disc eject properly?
 Check Result Action Code Commodity
Refer to RP451: Apple USB Issue resolved by
SuperDrive to open the drive removing stuck
enclosure and remove any stuck Yes disc or debris from
${nodeText.yesSymptomCode}
disc, dust, debris, or other foreign drive. Verify
materials. resolution.

13. Retest the Apple USB

SuperDrive by inserting,
mounting, and ejecting a known-
good optical disc. Go to step 14.
No ${nodeText.noSymptomCode}

Is optical drive function fully

restored?
Replace the Apple
Inform user that computer failures
USB SuperDrive.
due to accidental damage are not
Yes Verify issue J05 OPTICAL
covered under any Apple
resolved.
warranty, including AppleCare. If
applicable, discuss out-of-
14. Issue resolved.
warranty repair options.
Using proper
positioning, return
No ${nodeText.noSymptomCode}
the drive to the
Does user want to proceed with
user.
out-of-warranty repair?
Issue resolved.
Yes ${nodeText.yesSymptomCode}

Insert, mount, and eject a known-

good optical disc.
15. ESCALATION
No REQUIRED. J99
Is the issue resolved?
Contact ACS for
additional support
or a multiple-part
repair.
Flash Storage Not Recognized / Not Mounting /
Read/Write Issues
Unlikely causes:

Battery, camera, camera/microphone/ALS cable, fan, DisplayPort cable, display panel, left speaker, memory, power supply,
rear enclosure, right speaker, stand, Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

Important: Always ask if the user’s data has been backed up
before beginning the repair.

1. Disconnect all peripherals and attempt to start up the

computer.
2. To restore the default startup disk, reset the NVRAM
using the procedure for this computer in article
HT204063: How to Reset NVRAM on your Mac.
3. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Displays flashing folder with question mark or prohibitive Controller (SMC) on your Mac to return computer to a
symbol known power-off state. Try to turn on from power-off
Cannot save documents state. Do not hold in the power button when turning on
Displays read/write error message(s) the computer. You could inadvertently put the computer
Hangs when accessing or saving data into DFU mode if you do.
Drive or volume is not recognized in Disk Utility (icon is
grayed out). Warning: Be extremely careful when working inside the
Cannot erase volume, and bootable drive is not shown computer with power applied and the system energized. Avoid
in Disk Utility. touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
Note: Inform user that computer failures due to accidental with power supply covers to protect yourself when working
damage are not covered. If applicable, discuss out-of- inside the computer.
warranty repair options.
Before removing any components, be sure to turn off
computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Connect a known-good Apple Go to step 2.
Yes ${nodeText.yesSymptomCode}
wired keyboard and Apple wired
mouse to user's computer.

Press the power button to start

up the computer.

Confirm that computer completes

the startup process: Apple logo >
progress indicator > login screen Go to the “Will Not
1. > desktop or installer screen. Start Up”
No troubleshooting ${nodeText.noSymptomCode}
During startup, allow up to four flow.
minutes for a defective flash
storage to time out, after which
the computer will start up from a
known-good external device.

Does the computer start up

completely?

Run AST 2 Storage Diagnostic ESCALATION

on the user’s computer and REQUIRED.
examine the results of the test. Yes H99
2. Contact ACS for
additional support
Do all internal drive tests pass in or a multiple-part
Storage Diagnostic? repair.

Go to step 3.
No ${nodeText.noSymptomCode}
Examine Storage Diagnostic Go to step 4.
Pass ${nodeText.yesSymptomCode}
results for presence of an internal
drive.
3.
Go to step 12.
Fail ${nodeText.noSymptomCode}
Did drive presence test PASS or
FAIL?
Examine Storage Diagnostic Go to step 5.
Pass ${nodeText.yesSymptomCode}
results for SMART status.
4.
Go to step 12.
Fail ${nodeText.noSymptomCode}
Did SMART test PASS or FAIL?
Examine Storage Diagnostic Go to step 6.
Pass ${nodeText.yesSymptomCode}
results for Short Random Multi-
Block Read Test.
5.
Go to step 12.
Fail ${nodeText.noSymptomCode}
Did Short Random Multi-Block
Read Test PASS or FAIL?
Examine Storage Diagnostic Go to step 7.
Pass ${nodeText.yesSymptomCode}
results for File System Check.
6.
Go to step 9.
Fail ${nodeText.noSymptomCode}
Did File System Check PASS or
FAIL?
Examine Storage Diagnostic Go to step 8.
Pass ${nodeText.yesSymptomCode}
results for Bootable Volume
Presence Check.
7.
Go to step 9.
Fail ${nodeText.noSymptomCode}
Did Bootable Volume Check
PASS or FAIL?
 Check Result Action Code Commodity

Examine Storage Diagnostic

results for Last OS Reinstall ESCALATION
Check. Pass REQUIRED. H99
8.
Contact ACS for
Did Last OS Reinstall Check additional support
PASS or FAIL? or a multiple-part
repair.

Go to step 9.
Fail ${nodeText.noSymptomCode}
Hold down Command-R during Go to step 10.
Yes ${nodeText.yesSymptomCode}
startup to restart from the
recovery partition. Use Disk Utility
to repair the user’s internal flash
storage volume.

9. Attempt to start up from the

Go to step 11.
user’s internal flash storage. No ${nodeText.noSymptomCode}

Does the computer start up

successfully from the user’s
internal flash storage?
The issue is
resolved by
repairing the
volume using Disk
Yes ${nodeText.yesSymptomCode}
Utility.

Verify resolution.
Run AST Storage Diagnostic on
the user’s computer again and
examine the results of the test.
10.

Do all internal drive tests pass in

Storage Diagnostic? ESCALATION
No REQUIRED. H99

Contact ACS for

additional support
or a multiple-part
repair.
 Check Result Action Code Commodity
Hold down Command-R during Go to step 10.
Yes ${nodeText.yesSymptomCode}
startup to restart from the
recovery partition. Run Disk
Utility and select the user’s flash
storage drive.

Erase the flash storage drive

using Mac OS Extended (Case-
sensitive, Journaled) format, and
GUID Partition Map scheme.

Erase the flash storage drive

again using Mac OS Extended
(Journaled) format, and GUID
Partition Map scheme.

11. Formatting the drive twice with

different partition map schemes Go to step 12.
No ${nodeText.noSymptomCode}
will force a rewrite of the
partitions table.

Restore the correct version of

macOS on the computer. Use
Internet Recovery or a valid build
of macOS for this computer, as
per article HT201260: How to find
the macOS version number on
your Mac.

Does the computer start up

successfully from the user’s
internal flash storage?
Turn off computer. Unplug Go to step 13.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from AC
mains before proceeding.

Remove display panel and logic

board to gain access to flash
storage cards.

Disconnect and remove both

flash storage cards from the logic
board.

Note from which connector (left

or right) that each flash storage
card was removed. The cards
12.
must be reinstalled into the same Go to step 14.
No ${nodeText.noSymptomCode}
connectors from which they were
removed, or the computer will not
start up. Do not mix up the flash
storage cards.

Look for damage on logic board

connector and flash storage.

Look for connector pin damage

and missing or bent pins on logic
board connector that could
prevent correct seating.

Did you find damage to flash

storage or logic board
connectors?
 Check Result Action Code Commodity
Replace flash
storage.
Yes H04 SSD
Verify that the
issue is resolved.

Damage to multiple parts

requires an escalation to ACS for
repair approval.
13.

Is damage limited to flash ESCALATION

storage? No REQUIRED. H99
Contact ACS for
additional support
or a multiple-part
repair.

Reconnect user’s flash storage. Issue resolved by

Verify that the flash storage cards reseating flash
are properly seated to the logic Yes storage. Verify ${nodeText.yesSymptomCode}
board connector. resolution.

Note: Flash storage in this model

is in two matched parts, and must
be installed properly or the
computer will not start up. Refer
14. to service documentation for
more information.
Go to step 15.
No ${nodeText.noSymptomCode}
Run AST Storage Diagnostic on
the user’s computer again and
examine the results of the test.

Do all internal drive tests pass in

Storage Diagnostic?
Go to step 16.
To troubleshoot this issue Yes ${nodeText.yesSymptomCode}
completely, known-good bootable
Replace flash
flash storage is required.
storage.
15.
No H01 SSD
Verify that the
Do you have immediate access
issue is resolved.
to known-good flash storage?
Replace flash
Substitute known-good flash storage.
storage.
Yes H01 SSD
Verify that the
Run AST Storage Diagnostic on issue is resolved.
the user’s computer again and
16.
examine the results of the test. Replace flash
storage.
No M19 MLB
Do all internal drive tests pass in Verify that the
Storage Diagnostic? issue is resolved.
 Check Result Action Code Commodity
The issue is
resolved. Verify
Confirm that the computer can Yes ${nodeText.yesSymptomCode}
resolution.
successfully start up from internal
flash storage.

Run AST 2 Full System

Diagnostic (EFI & OS), if
17. available, to ensure no other
issues remain. ESCALATION
No REQUIRED. H99
Verify that the issue is resolved.
Contact ACS for
additional support
Is the issue resolved? or a multiple-part
repair.
SD Memory Card Cannot Be Inserted Into Slot
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, DisplayPort cable, hard disk drive (HDD), HDD data
or power or combo cable, display panel, left speaker, memory, power supply, rear enclosure, right speaker, solid-state drive
(SSD)/flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check

Symptoms Quick Check

1. Check that the user's SD card is not warped or
damaged, and that the metal contacts are clean, intact
and corrosion-free.
2. Verify that the SD card is the correct size. Card
dimensions should be 32 mm x 24 mm x 2.1 mm.

Note: Cards thicker than 2.1 mm are too thick and may
damage the card slot if inserted. Thinner cards such as
MultiMediaCards (MMC) are acceptable. Refer to article
HT204384: About the SD and SDXC card slot on your
Mac for further information.

3. Verify that the computer’s SD card slot is not obstructed

in any way. Use a flashlight to look into slot to make
sure nothing is already inserted. If so, carefully remove
the obstruction from the slot. Try to reinsert the SD
card.
Cannot insert SD card into slot. Warning: Be extremely careful when working inside the
Can insert SD card only part way into slot. computer with power applied and the system energized. Avoid
Card slot does not align with enclosure. touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
Note: Inform user that computer failures due to accidental with power supply covers to protect yourself when working
damage are not covered. If applicable, discuss out-of- inside the computer.
warranty repair options.
Before removing any components, be sure to turn off the
computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Issue resolved.
Defective or
incompatible SD
card. Advise user
to contact SD
Insert known-good, formatted SD card vendor for
card into user’s computer. Verify support. Refer
that it seats correctly. Yes them to article ${nodeText.yesSymptomCode}
1. HT204384: About
the SD and SDXC
Does known-good SD card seat
card slot on your
correctly when inserted?
Mac for further
information.

Go to step 2.
No ${nodeText.noSymptomCode}
Turn off computer. Unplug Go to step 3.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from AC
mains before proceeding.

Remove display panel.

Remove chin strap to avoid

bending or damaging it while
aligning logic board.
Replace logic
2.
Loosen but do not remove all logic board. Verify
No M27 MLB
board screws. You should be able issue resolved.
to shift board position slightly,
both left to right and up and down.
Take care to avoid damaging
cabling or other components while
moving logic board.

Insert known-good SD card again.

Can you now insert known-good

SD card correctly?
Issue resolved
Hold the logic board in position
with logic board
and tighten all logic board screws.
Yes alignment. Verify ${nodeText.yesSymptomCode}
Insert the known-good SD card
resolution.
again.
3.
Replace logic
board. Verify
Can you now insert and remove No M27 MLB
issue resolved.
known-good SD card correctly?
Issue resolved.
Yes ${nodeText.yesSymptomCode}

Verify that a known-good SD

memory card can be fully inserted
into and ejected from slot and that
4. it seats correctly. ESCALATION
No REQUIRED. M99

Is the issue resolved? Contact ACS for

additional support
or a multiple-part
repair.
SD Memory Card Not Recognized
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, fan, DisplayPort cable, hard disk drive (HDD), HDD data
or power or combo cable, display panel, left speaker, memory, power supply, rear enclosure, right speaker, solid-state drive
(SSD) / flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check

Symptoms Quick Check

1. Make sure the SD card is unlocked.
2. Check that the user's SD card is not warped or damaged
and that the metal contacts are clean, intact, and
corrosion free.
3. Verify that the computer's SD card slot is not damaged
or obstructed. Use a flashlight to inspect the slot to
make sure nothing is already inserted. If so, carefully
remove the obstruction from the slot. Try to reinsert the
SD card.
4. Verify that the SD card is the correct size. Card
dimensions should be 32 mm x 24 mm x 2.1 mm.

Note: Cards thicker than 2.1 mm are too thick and may
damage card slot if inserted. Thinner cards such as
MultiMediaCards (MMC) are acceptable. Refer to article
HT204384: About the SD and SDXC card slot on your
Mac for further specifications.

5. Consult article HT204384: About the SD and SDXC card

slot on your Mac and check for compatible SD card type
and format.
SD card does not appear on desktop or in System
SD card slot can accommodate cards that are Standard
Information.
SD (Secure Digital) 4MB to 2GB, SDHC (Secure Digital
High Capacity) 4GB to 32GB, and SDXC (Secure Digital
Note: Inform user that computer failures due to accidental
Extended Capacity) 4GB to 2TB. MMC cards can also
damage are not covered. If applicable, discuss out-of-
be used in this slot.
warranty repair options.
While SDIO (Secure Digital Input Output) cards fit into
and should not damage the card slot, they are not
supported.
MiniSD and Micro SD cards require adapters.

6. For a more specific SD card type or format (wireless-

enabled SD card or other SD card for example), make
sure the correct driver is installed. macOS supports only
standard SD memory cards; other cards may require
specific driver software.
7. Make sure Finder Preferences > General is set to show
External Disks.
8. Refer to HT204319: Use the Mac operating system that
came with your Mac, or a compatible newer version to
make sure system build is correct for this computer
model. Check for and apply the latest software and
firmware updates.
9. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
10. Reset the SMC using the procedure for this computer in
article HT201295: How to reset the System
Management Controller (SMC) on your Mac.

Deep Dive
 Check Result Action Code Commodity
Go to step 2.
Yes ${nodeText.yesSymptomCode}
Insert a known-good, formatted
SD card into user’s computer. Go to “SD
Verify that card seats correctly. Memory Card
1. Cannot Be
No Inserted Into Slot” ${nodeText.noSymptomCode}
Does known-good SD card seat troubleshooting
correctly when inserted? flow.

Verify that a known-good SD card Go to step 5.

Yes ${nodeText.yesSymptomCode}
appears in Disk Utility and
mounts in Finder. Verify that
computer can read data from and
2. write data to card.
Go to step 3.
No ${nodeText.noSymptomCode}

Can computer read from and

write to known-good SD card?
Start up user's computer with Repair
restore partition or up-to-date, permissions and
bootable macOS volume. Refer directory using
to HT204319: Use the Mac Disk Utility. If issue
operating system that came with persists, restore
your Mac, or a compatible newer macOS (with
version to make sure system Yes correct system ${nodeText.yesSymptomCode}
build is correct for this computer build). Retest to
3. model. verify resolution.
Check that user
Verify that a known-good SD card has necessary
appears and mounts in Disk driver software.
Utility and Finder.

Go to step 4.
No ${nodeText.noSymptomCode}
Can computer now read from and
write to known-good SD card?
Go to step 5.
Check System Information to Yes ${nodeText.yesSymptomCode}
verify that SD card reader is
Replace logic
listed in USB devices.
board, which
4.
includes SD card
No M27 MLB
reader. Verify
Does SD card reader appear in
issue resolved.
System Information?
Go to step 6.
Yes ${nodeText.yesSymptomCode}
Defective or
incompatible SD
Insert user's SD card into user’s card. Advise user
computer. Verify that it seats to contact SD card
correctly. manufacturer for
5. support. Refer
No user to article ${nodeText.noSymptomCode}
Does user's SD card seat HT204384: About
correctly when inserted? the SD and SDXC
card slot on your
Mac for further
information.

Verify that SD card appears in left Go to step 8.

Yes ${nodeText.yesSymptomCode}
column of Disk Utility. If card
does not appear, eject and
reinsert card. If inserted too
6. slowly, card may not appear.
Go to step 7.
No ${nodeText.noSymptomCode}

Does SD card appear in Disk

Utility?
 Check Result Action Code Commodity
Repair
permissions and
directory on
user’s computer
using Disk Utility. If
issue persists,
restore macOS
Yes (with correct ${nodeText.yesSymptomCode}
system build).
Retest to verify
Insert user’s SD card into a resolution. Check
known-good computer. Verify that that user has
computer can read data from and necessary driver
write data to SD card. software.
7.
Defective or
Can a known-good computer incompatible SD
read from and write to user's SD card. Advise user
card?
to contact SD card
manufacturer for
support. Refer
No user to article ${nodeText.noSymptomCode}
HT204384: About
the SD and SDXC
card slot on your
Mac for further
information.

Verify that user’s SD card Go to step 10.

Yes ${nodeText.yesSymptomCode}
volume appears in Disk Utility
and mounts in Finder.
8.
Go to step 9.
No ${nodeText.noSymptomCode}
Does card volume mount in
Finder or Disk Utility?
Issue resolved by
reformatting SD
Format user’s SD Card as Yes card. Verify ${nodeText.yesSymptomCode}
macOS Extended Journaled with resolution.
a GUID partition scheme.
Defective or
Important: Make sure user has a incompatible SD
valid backup first. If formatting is card. Advise user
successful, retest SD card by to contact SD card
9. manufacturer for
writing data to and retrieving data
from card. support. Refer
No user to article ${nodeText.noSymptomCode}
HT204384: About
Were you able to reformat, then the SD and SDXC
write to and read from the card card slot on your
successfully? Mac for further
information.
 Check Result Action Code Commodity

ESCALATION
REQUIRED.

Yes Verify issue M99

resolved.

Test user's SD card by writing If the issue

data to and retrieving data from persists, contact
card. ACS for additional
support.
10.
Were you able to write to and Defective or
read from user's card incompatible SD
successfully? card. Advise user
to contact SD card
manufacturer for
support. Refer
No user to article ${nodeText.noSymptomCode}
HT204384: About
the SD and SDXC
card slot on your
Mac for further
information.

Issue resolved.
Verify that user's computer can Yes ${nodeText.yesSymptomCode}
successfully read from and write
to a known-good SD card.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
11. available, to ensure no other ESCALATION
issues remain. No REQUIRED. M99

Verify that the issue is resolved. Contact ACS for

additional support
or a multiple-part
Is the issue resolved? repair.
Burnt Smell / Odor
Unlikely causes:
Rear enclosure, stand

Quick Check

Symptoms Quick Check

1. Verify that the computer is the source of odor.
2. Disconnect all third-party devices to eliminate external
devices as source of odor.
3. Odors can be related to how new the product is. Refer to
article HT202324: New equipment: Odors may be
present short-term.
4. Determine whether this is a safety issue. Refer to article
OP44: Handling Potential Product Safety Issues.
5. Inspect the enclosure and components for obvious signs
of burning or smoky residue. Check rear vents, slots,
ports, and power cord. Refer to article HT203529:
Smoke emitted may be from failed component.
6. Inspect the air intake vents and outlets for any
obstructions. Make sure air can flow freely into and out
of enclosure.
7. Clean the enclosure to eliminate odors resulting from
external contamination. Refer to article HT204172: How
to clean your Apple products. Explain the cause to the
user.
8. Verify functionality of the computer. If the computer is
nonfunctional, troubleshoot that first as a separate
Computer emits a burnt, smoky, or other unusual odor issue.

Note: Inform user that computer failures due to accidental Warning: Be extremely careful when working inside the
damage are not covered. If applicable, discuss out-of- computer with power applied and the system energized. Avoid
warranty repair options. touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity

ESCALATION
REQUIRED.
Closely inspect computer for a
possible safety issue. Contact ACS for
Yes T99
1. safety-related
issues.
Have you identified any safety
issues? Refer to article
OP44: Handling
Potential Product
Safety Issues.

Go to step 2.
No ${nodeText.noSymptomCode}
Odor can be related to external Go to step 3.
Yes ${nodeText.yesSymptomCode}
contamination. Inspect computer
exterior for contamination or lack
of cleanliness.
2.
Go to step 4.
No ${nodeText.noSymptomCode}
Can you determine that odor is
caused by external
contamination?
Issue resolved.
Yes Verify resolution. ${nodeText.yesSymptomCode}
Thoroughly clean the entire
enclosure and all external
surfaces. Refer to article
HT204172: How to clean your
Apple products. Explain cause to
3.
the user.
No ESCALATION M99
REQUIRED.
Does user agree that odor is due
to external contamination? Contact ACS for
additional support.

Odors can be related to how new Go to step 5.

Yes ${nodeText.yesSymptomCode}
the product is. Refer to article
HT202324: New equipment:
Odors may be present short-term.
4.
Go to step 6.
No ${nodeText.noSymptomCode}
Can you determine that odor is
due to newness?
Issue resolved.
Explain to user that new Yes Verify resolution. ${nodeText.yesSymptomCode}
computers can sometimes emit an
odor similar to odors generated by
new carpeting or a new car. In
most cases, odor dissipates after
a brief period. Refer user to article
5.
HT202324: New equipment:
Odors may be present short-term. No ESCALATION M99
REQUIRED.

Does user agree odor is related to Contact ACS for

computer's newness? additional support.
 Check Result Action Code Commodity

Inspect each module and its

associated cables for signs of
burnt or damaged components, ESCALATION
smoke residue or other traces of REQUIRED.
Yes M99
burning, and melted or damaged
6.
wiring. Contact ACS to
troubleshoot burnt
or failed
Have you identified a component components.
failure as source of odor?
Go to step 7.
No ${nodeText.noSymptomCode}
Closely inspect internal Go to step 8.
Yes ${nodeText.yesSymptomCode}
components and enclosure for
indications of physical damage or
internal contamination.
7.
Go to step 9.
No ${nodeText.noSymptomCode}
Can you identify signs of internal
damage or contamination?
Inform the user that computer Proceed with out-
failures due to accidental damage of-warranty repair.
Yes ${nodeText.yesSymptomCode}
are not covered under any Apple Verify resolution.
warranty, including AppleCare. If
applicable, discuss out-of- Issue resolved.
8.
warranty repair options. Return computer
to user using
No ${nodeText.noSymptomCode}
correct
Does user want to proceed with positioning.
out-of-warranty repair?
Run the computer for several Issue resolved.
Yes ${nodeText.yesSymptomCode}
hours and monitor for the
issue/odor.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
available, to ensure no other
issues remain.
9. ESCALATION
If no functional failure is detected, No REQUIRED. M99
use correct positioning to explain
to the user that the odor is related Contact ACS for
to external contamination or the additional support
computer being new. or a multiple-part
repair.

Is issue resolved?
Computer Runs Hot
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, DisplayPort cable, hard drive data or power or combo
cable, left speaker, memory, rear enclosure, right speaker, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check
 Symptoms Quick Check
1. Run Mac Resource Inspector (MRI) to verify correct
operation of sensors and fan.
2. Check for and apply latest software and firmware
updates.
3. Inspect fan performance during operation to make sure
fan is spinning. Check that vents are not blocked, and if
necessary, use compressed air to remove dust or debris
from rear fan exhaust.
4. Compare computer’s operating temperature to a
known-good, similarly configured computer.
5. Check for runaway applications using the information in
article HT203184: See how apps affect Mac
performance, battery runtime, temperature, and fan
activity. Follow the instructions to halt any processes
that are using excessive system resources.
6. Processor-intensive/graphics-intensive applications and
system processes may cause the enclosure to feel
warm. Use Activity Monitor to identify these types of
programs and explain issue to user.
7. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Controller (SMC) on your Mac to return computer to a
known power-off state. Try to turn on from power-off
state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
into DFU mode if you do.
8. Verify that computer’s internal hard drive or flash
storage is an Apple-installed part. Compare hard drive
Computer feels unusually warm. information in System Information to the Apple Hard
Fan is not operating. Drives Matrix in article SM155: Hard Drives Matrix to
Fan is not functioning to its full capacity. determine whether user’s installed drive is one of OEM
Fan runs constantly at high speeds. drives available for this computer configuration. Third-
party hard drives without correct firmware or thermal
Note: Inform user that computer failures due to accidental sensors, or outside this computer’s specifications, may
damage are not covered. If applicable, discuss out-of- cause computer to run hot or permanently activate fan at
warranty repair options. full speed. In such cases, inform user that computer has
been modified from its original, supported configuration,
and that such a repair would not be covered under
Apple warranty.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
Run diagnostics or Mac Go to step 2.
Yes ${nodeText.yesSymptomCode}
Resource Inspector (MRI) and
consult diagnostic logs to
check for fan (motor) or
sensor failures.

An inoperative or clogged fan

can cause the computer to run
hot.
1.
Go to step 8.
No ${nodeText.noSymptomCode}
Sensor(s) that indicate they
are out of normal operating
range can help isolate why the
computer is running hot.

Does computer pass all MRI

checks?
Use extended version of Computer passed
Cooling System Diagnostics all CSD tests.
(CSD) to verify proper function Verify operation
of the following subsystems: and refer user to
Yes article HT202179: ${nodeText.yesSymptomCode}
SMC Learn about the
Fan fans in your Mac.
2.
Thermal sensors
CPU–heat sink thermal
interface
Go to step 3.
No ${nodeText.noSymptomCode}
Does computer pass all CSD
tests?
Turn off computer. Unplug Issue resolved by
computer from AC mains by cleaning fan and
disconnecting both ends of its heat sink and
power cord. Ensure computer Yes reseating fan ${nodeText.yesSymptomCode}
is completely disconnected connections. Verify
from AC mains before resolution.
proceeding.

Remove display panel.

Remove all fan screws and

extract fan to reveal heat sink
or fan air duct. Use an ESD-
safe vacuum to remove dust
or debris from inner side of
heat sink fin stack. Clean fan
rotor blades. Reinstall fan and
3.
reseat fan cable connections
to logic board. Reassemble
and retest with CSD.
Go to step 4.
No ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does computer pass all CSD

checks?
 Check Result Action Code Commodity
To troubleshoot this issue Go to step 5.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan
is required.
4. Replace fan. Verify
OTHER
No issue resolved. X22
ELECTRIC
Do you have immediate
access to known-good fan?
Substitute a known-good fan Replace fan. Verify
OTHER
and retest using MRI and Yes issue resolved. X22
ELECTRIC
CSD.
5.
Go to step 6.
No ${nodeText.noSymptomCode}
Does computer now pass MRI
and CSD tests?
Go to step 7.
Yes ${nodeText.yesSymptomCode}
Reinstall user's
fan. Replace logic
To troubleshoot this issue
board.
completely, a known-good
logic board is required.
Use Blank Board
6. Serializer (BBS)
No to set the M18 MLB
Do you have immediate
computer’s serial
access to a known-good logic
number.
board?
Verify that the
issue is resolved.

Reinstall user's
fan. Replace logic
board.

Continue to use known-good Use Blank Board

fan. Substitute a known-good Serializer (BBS)
logic board. Reassemble Yes to set the M18 MLB
computer and retest with MRI. computer’s serial
7. number.

Do both known-good fan and Verify that the

logic board pass MRI and run- issue is resolved.
in tests?
Replace power
supply. Verify POWER
No P17
issue resolved. SUPPLY

Determine specific type of Voltage/Current Go to step 9.

${nodeText.yesSymptomCode}
failure reported in diagnostics: Sensor
thermal/fan sensor or
voltage/current sensor.

MRI thermal sensors

begin with Txxx.
8. MRI electrical voltage
Thermal/Fan Go to step 15.
sensors begin with Vxxx. ${nodeText.noSymptomCode}
Sensor
MRI electrical current
sensors begin with Ixxx.

Which sensor failure does

diagnostics report?
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 10.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Some power-related sensors

are located in power supply,
but are read through a SMBus
connection to logic board.
9.
Go to step 13.
No/Other ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does MRI report a VDxx or

IDxx test failure?
Go to step 11.
Yes ${nodeText.yesSymptomCode}
Reseat DC power cable
Issue resolved by
connection to logic board.
reseating DC
Reassemble and retest, using
power cable
MRI.
10. connection
No between power ${nodeText.noSymptomCode}
supply and logic
Does MRI still report a VDxx
board. Verify
or IDxx sensor test failure?
resolution.

Go to step 12.
Yes ${nodeText.yesSymptomCode}
To troubleshoot this issue DC power cable is
completely, a known-good part of power
power supply is required. supply.
11.
Replace power POWER
No P17
Do you have immediate supply. SUPPLY
access to a known-good
power supply? Verify that the
issue is resolved.
 Check Result Action Code Commodity
Reinstall user's
power supply.
Replace logic
board.

Use Blank Board

Serializer (BBS)
Yes M18 MLB
to set the
computer’s serial
Substitute a known-good
number.
power supply, reassemble and
retest using MRI.
Verify that the
12.
issue is resolved.
Does MRI still report a VDxx
DC power cable is
or IDxx sensor test failure?
part of power
supply.

Replace power POWER

No P17
supply. SUPPLY

Verify that the

issue is resolved.

Go to step 14.
Yes ${nodeText.yesSymptomCode}
Most voltage and current Replace logic
regulators are located on logic board.
board. To troubleshoot this
issue completely, a known- Use Blank Board
good logic board is required. Serializer (BBS)
13.
to set the
No M18 MLB
computer’s serial
Do you have immediate number.
access to a known-good logic
board? Verify that the
issue is resolved.

Reinstall user's
logic board.
Replace power POWER
Yes P17
supply. Verify SUPPLY
issue resolved.
Substitute a known-good logic
Replace logic
board, reassemble and retest
board.
using MRI.
14.
Use Blank Board
Serializer (BBS)
Does MRI still report a Vxxx or
to set the
Ixxxx sensor test failure? No M18 MLB
computer’s serial
number.

Verify that the

issue is resolved.

Identify specific type of failure Go to step 16.

Fan (Motor) ${nodeText.yesSymptomCode}
reported in MRI/diagnostics:
thermal sensor or fan (motor)
error.

15. MRI thermal sensors begin

Go to step 22.
with Txxx. Thermal ${nodeText.noSymptomCode}

Which sensor failure does

diagnostics report?
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 17.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Refer to the service guide

16.
Functional Overview to locate Go to step 19.
No ${nodeText.noSymptomCode}
affected fan connection to
logic board. Disconnect fan
cable connectors and inspect
logic board and fan cable
connector pins for damage.

Is there any cable or

connector damage on fan or
logic board?

Identify whether fan, logic ESCALATION

board, or both are damaged. REQUIRED.
Yes ${nodeText.yesSymptomCode}
17.
Contact ACS for
Are both fan and logic board additional support
damaged? or a multiple-part
repair.

Go to step 18.
No ${nodeText.noSymptomCode}
Replace fan. Verify
OTHER
Fan issue resolved. X22
ELECTRIC
Replace logic
board.
Identify whether fan or logic
board is damaged. Use Blank Board
18. Serializer (BBS)
to set the
Logic Board M24 MLB
Which part is damaged? computer’s serial
number.

Verify that the

issue is resolved.
 Check Result Action Code Commodity
Remove all fan screws and Issue resolved by
extract fan to reveal heat sink cleaning fan and
or fan air duct. Use an ESD- heat sink and
safe vacuum to remove dust Yes reseating fan ${nodeText.yesSymptomCode}
or debris from inner side of connections. Verify
heat sink fin stack. Clean fan resolution.
rotor blades. Reinstall fan and
reseat fan cable connections
to logic board. Reassemble
and retest with MRI.

Warning: HIGH VOLTAGE:

19.
The power supply remains
energized whenever the
computer is plugged in,
Go to step 20.
whether or not the computer No ${nodeText.noSymptomCode}
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does computer pass fan

motor check?
To troubleshoot this issue Go to step 21.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan
is required.
20. Replace fan. Verify
OTHER
No issue resolved. X22
ELECTRIC
Do you have immediate
access to a known-good fan?
Replace fan. Verify
OTHER
Yes issue resolved. X22
ELECTRIC
Reinstall user's
fan. Replace logic
Substitute a known-good fan, board.
and retest using MRI.
Use Blank Board
21.
Serializer (BBS)
Does computer now pass fan No to set the M08 MLB
motor check? computer’s serial
number.

Verify that the

issue is resolved.
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 23.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Remove all fan screws and

extract fan to reveal heat sink
or fan air duct. Use an ESD-
safe vacuum to remove dust
or debris from inner side of
Issue resolved by
heat sink fin stack. Clean fan
cleaning fan and
rotor blades. Reinstall fan and
22. heat sink and
reseat fan cable connections
No reseating fan ${nodeText.noSymptomCode}
to logic board. Reassemble
connections. Verify
and retest with MRI.
resolution.
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does MRI still report a Txxx

thermal sensor test failure?
Replace logic
Identify whether a thermal board.
sensor that is currently failing
MRI test is related to the logic Use Blank Board
board. Serializer (BBS)
to set the
Yes M23 MLB
Refer to service computer’s serial
23.
documentation for information number.
about thermal sensors.
Verify that the
issue is resolved.
Is a logic board thermal
sensor failing a test? Go to step 24.
No ${nodeText.noSymptomCode}
Identify whether a thermal Go to step 25.
Yes ${nodeText.yesSymptomCode}
sensor that is currently failing
MRI test is related to the Hard
Disk Drive (HDD) or Flash
Storage.
24.
Note: Some models do not Go to step 29.
No ${nodeText.noSymptomCode}
have a HDD.

Is a hard drive or flash storage

thermal sensor failing a test?
 Check Result Action Code Commodity
Go to step 26.
Yes ${nodeText.yesSymptomCode}
Verify in article SM155: Hard
Unsupported HDD
Drives Matrix that the installed
or Flash Storage
hard drive or flash storage
installed, or
model is compatible with this
missing/incorrect
25. computer configuration. hard drive thermal
No sensor. Check with ${nodeText.noSymptomCode}
user for out-of-
Is installed HDD or flash
warranty
storage compatible with this
resolution. Verify
model?
resolution.

Identify the type of storage Go to step 27.

HDD ${nodeText.yesSymptomCode}
device affected:

Hard Disk Drive (HDD) Replace the user's

26. Flash Storage flash storage.
Flash Storage Verify issue H85 SSD
resolved.
Is the affected device an HDD
or flash storage?
To troubleshoot this issue Go to step 28.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
hard drive data cable or hard
drive combo cable (depending
on model) is required.
Replace the user's
27.
hard drive. Verify
No H85 HDD
issue resolved.
Do you have immediate
access to a known-good hard
drive data cable or hard drive
combo cable?
Replace the user's
hard drive data
cable or hard drive
combo cable INTERNAL
Yes X03
(depending on CABLE
Substitute a known-good hard
model). Verify
drive data cable or hard drive
issue resolved.
combo cable (depending on
model) and retest using MRI.
28. Reinstall user's
hard drive data
cable or combo
Does computer now pass the
cable (depending
THxx sensor check?
No on model). H85 HDD
Replace the user's
hard drive. Verify
issue resolved.

Identify whether a thermal Replace power

sensor that is currently failing supply. Verify POWER
Yes P17
MRI test is related to the issue resolved. SUPPLY
power supply.
29.
Go to step 30.
No ${nodeText.noSymptomCode}
Is a power supply thermal
sensor failing a test?
 Check Result Action Code Commodity
Go to step 31.
Yes ${nodeText.yesSymptomCode}

Identify whether a thermal

sensor that is currently failing
MRI test is related to the ESCALATION
display. REQUIRED.
30.
No M99
Contact ACS for
Is a display thermal sensor additional support
failing a test? or a multiple-part
repair.

To troubleshoot this issue Go to step 32.

Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
31.
panel. Verify issue
No L85 LCD
Do you have immediate resolved.
access to a known-good
display panel?

ESCALATION
Substitute a known-good REQUIRED.
display panel and retest using
Yes ${nodeText.yesSymptomCode}
MRI. Contact ACS for
32. additional support
or a multiple-part
Does MRI still report a TL0p or repair.
TL1p thermal sensor test
failure?

Replace display
panel. Verify issue
No L85 LCD
resolved.

Issue resolved.
Yes ${nodeText.yesSymptomCode}

Run ASD or AST 2 Full

System Diagnostic (EFI &
OS), if available, to ensure no
other issues remain. ESCALATION
33. REQUIRED.
Verify that the issue is
No M99
resolved. Contact ACS for
additional support
or a multiple-part
Is the issue resolved? repair.
Mechanical/Physical/Cosmetic Damage
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

The computer shows signs of physical and/or cosmetic
damage such as:

Enclosure and stand:

Stand hinge is loose or broken.

Stand is bent, loose, or broken.
Screw is stripped, loose, or missing.
Scratches. Inspect computer and discuss nature of issue with user.
Dents. Determine whether user wants to proceed with repair (despite
Cracks. possible accidental damage) or pursue other service options.
Liquid spill. Click “No” to proceed with further troubleshooting.

Display Assembly: Note: For input device issues, including damage, go to the “
External Apple Bluetooth Peripherals” or “ External Apple
Broken glass. Wired Keyboard and Mouse” troubleshooting flows.
Cracked display panel.
Scratches.
Dents.
Liquid spill.

Note: Inform the user that computer failures due to accidental

damage are not covered. If applicable, discuss out-of-
warranty repair options.

Deep Dive

Check Result Action Code Commodity

Determine cause of damage

or defect: user/technician,
environment, accidental
damage, or abuse. Yes ESCALATION REQUIRED. X99
1.
Contact ACS for assistance with
Is an Apple agent Apple-related accidental
responsible for damage or damage.
defect on computer?
Go to step 2.
No ${nodeText.noSymptomCode}
Closely examine the user’s Proceed with the resolution or
computer for signs of repair using proper positioning.
enclosure damage, such as Inform the user that computer
the following: failures due to accidental
damage are not covered by
Stand hinge is loose or Apple’s one-year limited
broken. Yes warranty or the AppleCare X12 ENCLOSURE
2. Screw is stripped, Protection Plan (APP).
loose, or missing.
Stand is bent, loose, or Refer to
broken. www.apple.com/legal/warranty
for details.

Does the computer exhibit Go to step 3.

No ${nodeText.noSymptomCode}
this type of damage?
 Check Result Action Code Commodity
Proceed with the resolution or
repair using proper positioning.
Closely examine the user’s
Inform the user that computer
computer for signs of
failures due to accidental
enclosure damage, such as
damage are not covered by
the following:
Apple’s one-year limited
Yes warranty or the AppleCare X13 ENCLOSURE
Scratches
3. Protection Plan (APP).
Dents
Cracks
Refer to
www.apple.com/legal/warranty
for details.
Does the computer exhibit
this type of damage?
Go to step 4.
No ${nodeText.noSymptomCode}
Proceed with the resolution or
repair using proper positioning.
Closely examine the user’s
Inform the user that computer
computer enclosure for signs
failures due to accidental
of liquid spill damage.
damage are not covered by
Apple’s one-year limited
Look for any signs of liquid
Yes warranty or the AppleCare X90 ENCLOSURE
spill, liquid penetration, or
4. Protection Plan (APP).
liquid damage to the
computer’s enclosure.
Refer to
www.apple.com/legal/warranty
for details.
Does the computer exhibit
this type of damage?
Go to step 5.
No ${nodeText.noSymptomCode}
Proceed with the resolution or
repair using proper positioning.
Inform the user that computer
Closely examine the user’s
failures due to accidental
computer for signs of display
damage are not covered by
damage, such as a cracked,
Apple’s one-year limited
dented, or broken display
Yes warranty or the AppleCare L18 LCD
frame and/or assembly
5. Protection Plan (APP).
housing.
Refer to
www.apple.com/legal/warranty
Does the computer exhibit
for details.
this type of damage?
Go to step 6.
No ${nodeText.noSymptomCode}
Proceed with the resolution or
repair using proper positioning.
Closely examine the user’s Inform the user that computer
computer display panel for failures due to accidental
signs of cosmetic damage, damage are not covered by
such as the following: Apple’s one-year limited
Yes warranty or the AppleCare L19 LCD
6. Scratches Protection Plan (APP).
Dents
Refer to
www.apple.com/legal/warranty
Does the computer exhibit for details.
this type of damage?
Go to step 7.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Proceed with the resolution or
Closely examine the user’s
repair using proper positioning.
computer display panel for
Inform the user that computer
signs of a single hairline
failures due to accidental
crack.
damage are not covered by
Apple’s one-year limited
A single hairline crack is one
Yes warranty or the AppleCare L35 LCD
continuous curved or straight
7. Protection Plan (APP).
crack. It may travel across
the whole screen or cover a
Refer to
small area.
www.apple.com/legal/warranty
for details.
Does the computer exhibit
this type of damage? Go to step 8.
No ${nodeText.noSymptomCode}
Proceed with the resolution or
repair using proper positioning.
Closely examine the user’s Inform the user that computer
computer display panel for failures due to accidental
signs of multiple cracks. damage are not covered by
Apple’s one-year limited
Two or more glass cracks, or Yes warranty or the AppleCare L36 LCD
8. two or more hairline cracks, Protection Plan (APP).
count as multiple cracks.
Refer to
www.apple.com/legal/warranty
Does the computer exhibit for details.
this type of damage?
Go to step 9.
No ${nodeText.noSymptomCode}
Proceed with the resolution or
repair using proper positioning.
Inform the user that computer
failures due to accidental
damage are not covered by
Apple’s one-year limited
Closely examine the user’s Yes warranty or the AppleCare L90 LCD
computer display panel for Protection Plan (APP).
signs of liquid spill damage.
Refer to
Look for any signs of liquid www.apple.com/legal/warranty
spill, liquid penetration, or for details.
9.
liquid damage to the
computer’s display panel.

Does the computer exhibit

this type of damage?
No ESCALATION REQUIRED. ${nodeText.noSymptomCode}

Contact ACS for assistance with

Apple-related accidental
damage.
Noise/Hum/Vibration
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, DisplayPort cable, hard disk drive (HDD), hard drive data
or power or combo cable, display panel, left speaker, logic board, memory, rear enclosure, right speaker, solid-state drive
(SSD)/flash storage card, stand, Wi-Fi/Bluetooth antenna(s), wireless card

Quick Check

Symptoms Quick Check

Note: Verify the issue after using the computer for a few
minutes to warm it, or by following steps in HT207571: Warm
a Mac for testing. Doing this may help identify intermittent
issues.

1. Work with the user to reproduce the issue and isolate

the source of noise. Differentiate whether the noise is
coming from the computer or a connected peripheral.
Disconnect all third-party peripherals to isolate the
source of noise.
2. Determine whether the sound is normal or abnormal.
Refer to article TS3204: iMac: Evaluating System noises
for more information.
3. If the iMac fan runs at full speed after the computer turns
on, you may need to reset the iMac’s SMC. Refer to
articles HT204463: iMac: Fans run at full speed after
computer turns on and HT202179: About fans and fan
noise in your Apple product for more information. Reset
SMC using procedure listed for this computer in article
HT201295: How to reset the System Management
Controller (SMC) on your Mac.
4. Verify that the vents on the bottom and back of the
computer are free of dust and other obstructions that
Buzzing noise
might inhibit proper airflow through the computer.
Rattling noise
Ticking noise 5. Launch Applications > Utilities > Activity Monitor.
Determine whether an application or process is
Squeaking noise
consuming a high percentage of CPU bandwidth. CPU-
Humming noise
intensive applications can cause fan to run fast in order
High frequency noise
to maintain proper internal computer temperatures. If
Mechanical vibration
needed, quit application or restart the computer to
resolve issue.
Note: Inform user that computer failures due to accidental
damage are not covered. If applicable, discuss out-of-
Warning: Be extremely careful when working inside the
warranty repair options.
computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with Power Supply Covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off the

computer and unplug it from AC mains by disconnecting both
ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety
Deep Dive

Check Result Action Code Commodity

Issue resolved.
Issue caused by
ground loop
induced by third-
party devices.
Disconnect any peripheral
Advise user to
devices, cards, or cables
Yes connect all devices ${nodeText.yesSymptomCode}
attached to computer.
1. to a common
power outlet or
contact device
Has the noise been eliminated?
manufacturer for
support.

Go to step 2.
No ${nodeText.noSymptomCode}
Tilt display to hinge limits to Go to
determine whether mechanical “Stand/Hinge
noise is generated by hinge Issues”
Yes ${nodeText.yesSymptomCode}
mechanism. troubleshooting
2.
flow.

Is the noise coming from iMac's Go to step 3.

No ${nodeText.noSymptomCode}
display hinge?
Turn off computer. Unplug Replace power
computer from AC mains by supply. Verify POWER
Yes P04
disconnecting both ends of its issue resolved. SUPPLY
power cord. Ensure computer is
completely disconnected from AC
mains before proceeding.

Remove display panel.

Connect computer to AC power

and listen carefully around power
supply to verify whether it is
source of noise.
3.
Warning: HIGH VOLTAGE: The
Go to step 4.
power supply remains No ${nodeText.noSymptomCode}
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Is noise coming from iMac's

power supply?
 Check Result Action Code Commodity
Shut down computer. If you Issue resolved by
reinstalled display panel, remove removing loose
it. Yes objects inside chin ${nodeText.yesSymptomCode}
area.
Hold computer firmly with both
hands and invert computer while
gently shaking it, to attempt to
dislodge and remove any loose
screws or other foreign objects
that may have fallen down inside
4. the computer into the chin area.

Loose objects in the chin area Go to step 5.

No ${nodeText.noSymptomCode}
can cause noise or vibration,
especially during audio playback.

Briefly retest for noise, hum, or

vibration.

Has noise been eliminated?

Shut down computer and let it Go to step 6.
Yes ${nodeText.yesSymptomCode}
cool off fully. Check for noise,
hum or vibration during startup
when computer is cold.
5.
Go to step 12.
No ${nodeText.noSymptomCode}
Does issue happen on or after a
cold startup?
An unreadable thermal sensor Go to “Computer
can cause fan to run excessively. Runs Hot”
Run Mac Resource Inspector Yes troubleshooting ${nodeText.yesSymptomCode}
(MRI) to check thermal sensors. flow.
6.

Go to step 7.
Does MRI report any thermal No ${nodeText.noSymptomCode}
sensor failures?
Excessive fan operation may also Go to step 8.
Yes ${nodeText.yesSymptomCode}
occur if computer is unable to
read fan speed. Check MRI
results for fan (motor) sensor test
7. results.
Go to step 10.
No ${nodeText.noSymptomCode}

Does MRI report any fan (motor)

failures?
To troubleshoot this issue Go to step 9.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan is
required.
8. Replace fan. Verify
OTHER
No issue resolved. X23
ELECTRIC
Do you have immediate access
to known-good fan?
Replace fan. Verify
OTHER
Substitute known-good fan and Yes issue resolved. X23
ELECTRIC
retest with MRI.
Reinstall user's
9.
fan. Replace the
Does known-good fan pass fan No logic board. Verify M23 MLB
(motor) test in MRI? issue resolved.

Disconnect fan and briefly retest Go to step 11.

Yes ${nodeText.yesSymptomCode}
for noise, hum, or vibration.
10.
Go to step 12.
No ${nodeText.noSymptomCode}
Has noise been eliminated?
 Check Result Action Code Commodity
Verify whether any tape, gasket, Issue resolved by
cable label, cable, or other securing internal
material is touching fan blades components or
and causing a ticking or buzzing material to prevent
Yes ${nodeText.yesSymptomCode}
noise. Secure material so it does touching fan
not touch fan blades. If tape blades. Verify
adhesive has lost its stickiness, resolution.
replace that section of tape.

Remove fan and rotate blades.

Verify that fan blades spin
smoothly without interference
11. from fan housing, cables, tape,
gaskets or other components.

Reinstall fan while carefully Replace fan. Verify

OTHER
ensuring that there are no cables No issue resolved. X23
ELECTRIC
routed under or near fan
assembly that might cause
interference with fan blades. After
reassembling computer, verify
whether noise issue is resolved.

Has noise been eliminated?

Depending on configuration, Go to step 13.
Yes ${nodeText.yesSymptomCode}
there may or may not be a hard
drive installed. Other
configurations may have either a
flash storage card or both flash
12.
storage and HDD. Go to step 14.
No ${nodeText.noSymptomCode}

Is a hard drive installed in

computer?
Remove internal hard drive and Go to “HDD
start up computer from recovery Noisy”
partition or an up-to-date, Yes troubleshooting ${nodeText.yesSymptomCode}
13. bootable macOS volume. flow.

Go to step 14.
No ${nodeText.noSymptomCode}
Has noise been eliminated?
Play sound sample at loud and Go to “Distorted
soft volume levels to determine Audio from Internal
whether noise is caused by Speaker(s)”
Yes ${nodeText.yesSymptomCode}
left/right speakers or amplifier troubleshooting
circuit. Plug in external flow.
headphones to identify whether
14. noise comes from audio out or
from other source. Mute
computer volume. Verify whether
Go to step 15.
issue still occurs. No ${nodeText.noSymptomCode}

Has noise been eliminated?

To troubleshoot this issue Go to step 16.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan is
required.
15.
Go to step 17.
No ${nodeText.noSymptomCode}
Do you have immediate access
to a known-good fan?
Substitute known-good fan and Replace fan. Verify
OTHER
retest. Yes issue resolved. X23
ELECTRIC
16.
Go to step 18.
No ${nodeText.noSymptomCode}
Has noise been eliminated?
 Check Result Action Code Commodity
Disconnect fan and briefly retest Replace fan. Verify
OTHER
for noise, hum, or vibration. Yes issue resolved. X23
ELECTRIC
17.
Go to step 18.
No ${nodeText.noSymptomCode}
Has noise been eliminated?
With hard drive and fan Replace logic
disconnected, briefly retest once board. Verify issue
Yes M24 MLB
again while listening closely for resolved.
any noise, hum, or vibration
coming from logic board and heat
sink assembly.

Inspect logic board and heat sink

assembly for any damage that
may have occurred during
removal or replacement.

Logic board and heat sink

assembly must be treated as a
single unit during removal or
replacement. All screws must be
removed from both components
prior to physically pulling or
pushing either component.

Any mishandling of heat sink

18. assembly that is attached to logic
board can cause damage to heat
Go to step 19.
pipes connecting these No ${nodeText.noSymptomCode}
components.

If heat pipes become even

slightly damaged (bent or kinked
for example), normal heat
removal cycle can become
disrupted, causing a repetitive
hammering noise from this area.
Damage may not be visibly
noticeable.

Noise may be mistaken for a

faulty hard drive. Check for this
noise with hard drive and fan
disconnected.

Is there noise coming from logic

board and heat sink assembly?
Issue resolved.
Yes ${nodeText.yesSymptomCode}
Noise may be related to
interference from other electrical
devices operating near computer
or plugged into same power
outlet. See whether noise is
19. eliminated when computer runs in ESCALATION
a different location on a different No REQUIRED. X99
circuit.
Contact ACS for
additional support
Has noise been eliminated? or a multiple-part
repair.
 Check Result Action Code Commodity
Issue resolved.
Confirm that the computer’s Yes ${nodeText.yesSymptomCode}
noise, hum, or vibration has been
eliminated.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
20. available, to ensure no other ESCALATION
issues remain. No REQUIRED. M99

Verify that the issue is resolved. Contact ACS for

additional support
or a multiple-part
Is the issue resolved? repair.
Stand/Hinge Issues
Unlikely causes:
There are no unlikely causes for this issue.

Quick Check

Symptoms Quick Check

1. Inspect the computer and discuss the nature of issue
with the user. Determine whether the user wants to
proceed with repair (despite possible accidental
damage) or pursue other service options.
2. Click “No” to proceed with further troubleshooting.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
Bent stand inside the computer.
Broken hinge
Stripped screw/head Before removing any components, be sure to turn off the
Stripped screw boss/threads computer and unplug it from AC mains by disconnecting both
Loose stand and/or hinge ends of the power cord. Ensure the computer is completely
disconnected from AC mains before proceeding.
Note: Inform user that computer failures due to accidental
damage are not covered. If applicable, discuss out-of- For additional safety information and tips, refer to articles:
warranty repair options.
TP833: iMac and Displays: Power Supply Cover
Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive

Check Result Action Code Commodity

Determine cause of damage

or defects: user/technician,
environment, accidental
damage, or abuse. Yes ESCALATION REQUIRED. X99
1.
Contact ACS for assistance with
Is an Apple agent Apple-related accidental
responsible for damage or damage.
defect on the computer?
Go to step 2.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity

Inspect stand to determine ESCALATION REQUIRED.

whether it requires
replacement. Replace stand. Verify issue
resolved.
Verify that stand securely
holds computer in its upright Yes Inform user that failures due to X99
2. position without wobbling accidental damage are not
when placed on a hard, covered by Apple’s one-year
smooth, even surface. limited warranty or the AppleCare
Protection Plan. Refer to
www.apple.com/legal/warranty.
Is stand damaged or
defective? Contact ACS for additional
support regarding warranty
coverage for this part.

Go to step 3.
No ${nodeText.noSymptomCode}
Inspect hinge mechanism to Replace hinge mechanism.
determine whether it requires Verify issue resolved.
replacement.
Inform user that failures due to
Adjust computer back and accidental damage are not PIECE
Yes X12
forth on its hinge, listening covered by Apple’s one-year PART
for hinge noise. Check feel of limited warranty or AppleCare
the hinge. Its movement Protection Plan. Refer to
3. should feel firm—not tight or www.apple.com/legal/warranty.
loose—as it holds the iMac
in position. Hinge should
operate smoothly along its
entire travel.
Go to step 4.
No ${nodeText.noSymptomCode}

Is hinge mechanism
damaged or defective?
Place the customer's iMac on
a solid, flat surface.

Have another person apply

downward pressure to the ESCALATION REQUIRED.
stand to hold it down on that
solid surface. Replace the rear enclosure.
Verify issue resolved.
Firmly grasp both sides of
the iMac enclosure, and Inform user that failures due to
gently attempt to rotate the Yes accidental damage are not
X99
entire enclosure left and right covered by Apple’s one-year
while facing the display. The limited warranty or the AppleCare
enclosure should not be able Protection Plan. Refer to
to move in this direction. www.apple.com/legal/warranty.
4.
Compare this behavior with a Contact ACS for additional
known-good, similar iMac support regarding warranty
model. coverage for this part.
If the enclosure rotates an
abnormal amount, the
mechanism mounts inside
the rear enclosure may no
longer be securely attached,
which may require a rear Go to step 5.
No ${nodeText.noSymptomCode}
enclosure replacement.

Does the iMac's enclosure

rotate an abnormal amount?
 Check Result Action Code Commodity

Place the user’s iMac on a

solid, flat surface and check
if one side of the display
appears to sit higher or lower
Yes ESCALATION REQUIRED. X99
than the other side.
5.
Contact ACS for additional
Does one side of the iMac support or a multiple-part repair.
appear to sit higher or lower
than the other side? Go to step 6.
No ${nodeText.noSymptomCode}
Issue resolved.
Yes ${nodeText.yesSymptomCode}
Verify that both stand and
hinge operate properly and
that they securely hold the
iMac upright in all
6.
appropriate positions.
No ESCALATION REQUIRED. X99

Is the issue resolved? Contact ACS for additional

support or a multiple-part repair.
Intermittent Shutdown
Unlikely causes:
Battery, camera, camera/microphone/ALS cable or camera cable, DisplayPort cable, left speaker, memory, rear enclosure,
right speaker, stand, Wi-Fi/Bluetooth antennas, wireless card

Quick Check
 Symptoms Quick Check
Note: Verify the issue after using the computer for a few
minutes to warm it, or by following steps in HT207571: Warm
a Mac for testing. Doing this may help identify intermittent
issues.

1. Run Mac Resource Inspector (MRI) to verify correct

operation of sensors and fan.
2. Check for and apply latest software and firmware
updates.
3. Inspect fan performance during operation to make sure
fan is spinning. Check that vents are not blocked, and if
necessary, use compressed air to remove dust or debris
from rear fan exhaust.
4. Compare computer’s operating temperature to a
known-good, similarly configured computer.
5. Check for runaway applications using the information in
article HT203184: See how apps affect Mac
performance, battery runtime, temperature, and fan
activity. Follow the instructions to halt any processes
that are using excessive system resources.
6. Processor-intensive/graphics-intensive applications and
system processes may cause the enclosure to feel
warm. Use Activity Monitor to identify these types of
programs and explain issue to user.
7. Reset SMC using the procedure listed for this computer
in HT201295: How to reset the System Management
Controller (SMC) on your Mac to return computer to a
known power-off state. Try to turn on from power-off
state. Do not hold in the power button when turning on
the computer. You could inadvertently put the computer
into DFU mode if you do.
Shuts down during startup
8. Verify that computer’s internal hard drive or flash
Shuts down unexpectedly during use
storage is an Apple-installed part. Compare hard drive
Computer restarts spontaneously
information in System Information to the Apple Hard
Turns off when waking from sleep
Drives Matrix in article SM155: Hard Drives Matrix to
determine whether user’s installed drive is one of OEM
Note: Inform user that computer failures due to accidental
drives available for this computer configuration. Third-
damage are not covered. If applicable, discuss out-of-
party hard drives without correct firmware or thermal
warranty repair options.
sensors, or outside this computer’s specifications, may
cause computer to run hot or permanently activate fan at
full speed. In such cases, inform user that computer has
been modified from its original, supported configuration,
and that such a repair would not be covered under
Apple warranty.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP833: iMac and Displays: Power Supply Cover

Instructions
TP820: iMac (27-inch): Safety
TP914: iMac (21.5-inch): Safety

For iMac Pro (2017), refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety
Deep Dive

Check Result Action Code Commodity

Run diagnostics or Mac Go to step 2.
Yes ${nodeText.yesSymptomCode}
Resource Inspector (MRI) and
consult diagnostic logs to
check for fan (motor) or
sensor failures.

Sensors that indicate they are

out of normal operating range
or an inoperative fan can
1.
cause intermittent shutdowns. Go to step 5.
No ${nodeText.noSymptomCode}
Refer to service
documentation for sensor
information.

Does computer pass all MRI

checks?
Start up from internal drive Go to step 3.
Yes ${nodeText.yesSymptomCode}
and attempt to reproduce
shutdown symptom(s).
2.
Go to step 4.
No ${nodeText.noSymptomCode}
Can you reproduce shutdown
event?

ESCALATION
Yes REQUIRED. M99
Contact ACS for
further assistance.
Connect a known-good Apple
wired keyboard and Apple
wired mouse to user's
computer. Repair disk
directory using
Use macOS Recovery to Disk Utility. If the
3. troubleshoot potential software issue persists after
repair, refer to
issues. Hold down Command-
R during startup to restart from article HT201260:
the recovery partition. How to find the
macOS version
number on your
Does shutdown issue persist? No Mac and install the
${nodeText.noSymptomCode}
correct macOS
version and build
on user's hard
drive. Check for
and apply latest
software and
firmware updates.
Verify issue
resolved.
 Check Result Action Code Commodity
Replace logic
board.

Use Blank Board

Serializer (BBS)
to set the
Yes M08 MLB
computer’s serial
Run ASD or AST 2 extended number.
memory tests, if available,
repeatedly to verify that the Verify that the
computer does not issue is resolved.
4. unexpectedly shut down.
No failure found
during repeated
Did computer shut down diagnostic testing.
unexpectedly? Using correct
positioning, return
No computer to user ${nodeText.noSymptomCode}
with no trouble
found. Verify that
the issue is
resolved.

Determine specific type of Voltage/Current Go to step 6.

${nodeText.yesSymptomCode}
failure reported in diagnostics: Sensor
thermal/fan sensor or
voltage/current sensor.

MRI thermal sensors

begin with Txxx.
5. MRI electrical voltage
Thermal/Fan Go to step 12.
sensors begin with Vxxx. ${nodeText.noSymptomCode}
Sensor
MRI electrical current
sensors begin with Ixxx.

Which sensor failure does

diagnostics report?
Turn off computer. Unplug Go to step 7.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Some power-related sensors

are located in power supply,
but are read through a SMBus
connection to logic board.
6.
Go to step 10.
No/Other ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does MRI report a VDxx or

IDxx test failure?
 Check Result Action Code Commodity
Go to step 8.
Yes ${nodeText.yesSymptomCode}
Reseat DC power cable
Issue resolved by
connection to logic board.
reseating DC
Reassemble and retest, using
power cable
MRI.
7. connection
No between power ${nodeText.noSymptomCode}
supply and logic
Does MRI still report a VDxx
board. Verify
or IDxx sensor test failure?
resolution.

Go to step 9.
Yes ${nodeText.yesSymptomCode}
To troubleshoot this issue DC power cable is
completely, a known-good part of power
power supply is required. supply.
8.
Replace power POWER
No P02
Do you have immediate supply. SUPPLY
access to a known-good
power supply? Verify that the
issue is resolved.

Reinstall user's
power supply.
Replace logic
board.

Use Blank Board

Serializer (BBS)
Yes M08 MLB
to set the
computer’s serial
Substitute a known-good
number.
power supply, reassemble and
retest using MRI.
Verify that the
9.
issue is resolved.
Does MRI still report a VDxx
DC power cable is
or IDxx sensor test failure?
part of power
supply.

Replace power POWER

No P02
supply. SUPPLY

Verify that the

issue is resolved.

Go to step 11.
Yes ${nodeText.yesSymptomCode}
Most voltage and current Replace logic
regulators are located on logic board.
board. To troubleshoot this
issue completely, a known- Use Blank Board
good logic board is required. Serializer (BBS)
10.
to set the
No M08 MLB
computer’s serial
Do you have immediate number.
access to a known-good logic
board? Verify that the
issue is resolved.
 Check Result Action Code Commodity
Reinstall user's
logic board.
Replace power POWER
Yes P02
supply. Verify SUPPLY
issue resolved.
Substitute a known-good logic
Replace logic
board, reassemble and retest
board.
using MRI.
11.
Use Blank Board
Serializer (BBS)
Does MRI still report a Vxxx or
to set the
Ixxxx sensor test failure? No M08 MLB
computer’s serial
number.

Verify that the

issue is resolved.

Identify specific type of failure Go to step 13.

Fan (Motor) ${nodeText.yesSymptomCode}
reported in MRI/diagnostics:
thermal sensor or fan (motor)
error.

12. MRI thermal sensors begin

Go to step 19.
with Txxx. Thermal ${nodeText.noSymptomCode}

Which sensor failure does

diagnostics report?
Turn off computer. Unplug Go to step 14.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Refer to the service guide

13.
Functional Overview to locate Go to step 16.
No ${nodeText.noSymptomCode}
affected fan connection to
logic board. Disconnect fan
cable connectors and inspect
logic board and fan cable
connector pins for damage.

Is there any cable or

connector damage on fan or
logic board?

ESCALATION
Identify whether fan, logic REQUIRED.
board, or both are damaged.
Yes ${nodeText.yesSymptomCode}
14. Contact ACS for
additional support
Are both fan and logic board or a multiple-part
damaged? repair.

Go to step 15.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Replace fan. Verify
OTHER
Fan issue resolved. X22
ELECTRIC
Replace logic
board.
Identify whether fan or logic
board is damaged. Use Blank Board
15. Serializer (BBS)
to set the
Logic Board M24 MLB
Which part is damaged? computer’s serial
number.

Verify that the

issue is resolved.

Remove all fan screws and Issue resolved by

extract fan to reveal heat sink cleaning fan and
or fan air duct. Use an ESD- heat sink and
safe vacuum to remove dust Yes reseating fan ${nodeText.yesSymptomCode}
or debris from inner side of connections. Verify
heat sink fin stack. Clean fan resolution.
rotor blades. Reinstall fan and
reseat fan cable connections
to logic board. Reassemble
and retest with MRI.

Warning: HIGH VOLTAGE:

16.
The power supply remains
energized whenever the
computer is plugged in,
Go to step 17.
whether or not the computer No ${nodeText.noSymptomCode}
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does computer pass fan

motor check?
To troubleshoot this issue Go to step 18.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan
is required.
17. Replace fan. Verify
OTHER
No issue resolved. X22
ELECTRIC
Do you have immediate
access to a known-good fan?
Replace fan. Verify
OTHER
Yes issue resolved. X22
ELECTRIC
Reinstall user's
fan. Replace logic
Substitute a known-good fan, board.
and retest using MRI.
Use Blank Board
18.
Serializer (BBS)
Does computer now pass fan No to set the M08 MLB
motor check? computer’s serial
number.

Verify that the

issue is resolved.
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 20.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer
is completely disconnected
from AC mains before
proceeding.

Remove display panel.

Remove all fan screws and

extract fan to reveal heat sink
or fan air duct. Use an ESD-
safe vacuum to remove dust
or debris from inner side of
Issue resolved by
heat sink fin stack. Clean fan
cleaning fan and
rotor blades. Reinstall fan and
19. heat sink and
reseat fan cable connections
No reseating fan ${nodeText.noSymptomCode}
to logic board. Reassemble
connections. Verify
and retest with MRI.
resolution.
Warning: HIGH VOLTAGE:
The power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does MRI still report a Txxx

thermal sensor test failure?
Replace logic
Identify whether a thermal
board.
sensor that is currently failing
MRI test is related to the logic
Use Blank Board
board.
Serializer (BBS)
to set the
Refer to service Yes M23 MLB
computer’s serial
20. documentation for thermal
number.
sensor information and
locations.
Verify that the
issue is resolved.
Is a logic board thermal
Go to step 21.
sensor failing a test? No ${nodeText.noSymptomCode}
Identify whether a thermal Go to step 22.
Yes ${nodeText.yesSymptomCode}
sensor that is currently failing
MRI test is related to the Hard
Disk Drive (HDD) or Flash
Storage.
21.
Note: Some models do not Go to step 26.
No ${nodeText.noSymptomCode}
have a HDD.

Is a hard drive or flash storage

thermal sensor failing a test?
 Check Result Action Code Commodity
Go to step 23.
Yes ${nodeText.yesSymptomCode}
Verify in article SM155: Hard
Unsupported HDD
Drives Matrix that the installed
or Flash Storage
hard drive or flash storage
installed, or
model is compatible with this
missing/incorrect
22. computer configuration. hard drive thermal
No sensor. Check with ${nodeText.noSymptomCode}
user for out-of-
Is installed HDD or flash
warranty
storage compatible with this
resolution. Verify
model?
resolution.

Identify the type of storage Go to step 24.

HDD ${nodeText.yesSymptomCode}
device affected:

Hard Disk Drive (HDD) Replace the

23. Flash Storage user’s flash
Flash Storage storage. Verify H85 SSD
issue resolved.
Is the affected device an HDD
or flash storage?
To troubleshoot this issue Go to step 25.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
hard drive data cable or hard
drive combo cable (depending
on model) is required.
Replace the user's
24.
hard drive. Verify
No H85 HDD
issue resolved.
Do you have immediate
access to a known-good hard
drive data cable or hard drive
combo cable?
Replace the user's
hard drive data
cable or hard drive
combo cable INTERNAL
Yes X03
(depending on CABLE
Substitute a known-good hard
model). Verify
drive data cable or hard drive
issue resolved.
combo cable (depending on
model) and retest using MRI.
25. Reinstall user's
hard drive data
cable or combo
Does computer now pass the
cable (depending
THxx sensor check?
No on model). H85 HDD
Replace the user's
hard drive. Verify
issue resolved.

Identify whether a thermal Replace power

sensor that is currently failing supply. Verify POWER
Yes P02
MRI test is related to the issue resolved. SUPPLY
power supply.
26.
Go to step 27.
No ${nodeText.noSymptomCode}
Is a power supply thermal
sensor failing a test?
 Check Result Action Code Commodity
Go to step 28.
Yes ${nodeText.yesSymptomCode}

Identify whether a thermal

sensor that is currently failing
MRI test is related to the
display. ESCALATION
27.
No REQUIRED. M99
Is a display thermal sensor Contact ACS for
failing a test? additional support
or a multiple-part
repair.

To troubleshoot this issue Go to step 29.

Yes ${nodeText.yesSymptomCode}
completely, a known-good
display panel is required.
Replace display
28.
panel. Verify issue
No L85 LCD
Do you have immediate resolved.
access to a known-good
display panel?

ESCALATION
Substitute a known-good REQUIRED.
display panel and retest using
Yes ${nodeText.yesSymptomCode}
MRI. Contact ACS for
29. additional support
or a multiple-part
Does MRI still report a TL0p or repair.
TL1p thermal sensor test
failure?

Replace display
panel. Verify issue
No L85 LCD
resolved.

Issue resolved.
Yes ${nodeText.yesSymptomCode}

Run ASD or AST 2 Full

System Diagnostic (EFI &
OS), if available, to ensure no
other issues remain. ESCALATION
30. REQUIRED.
Verify that the issue is
No M99
resolved. Contact ACS for
additional support
or a multiple-part
Is the issue resolved? repair.
Kernel Panic / System Crashes
Unlikely causes:
Battery, DisplayPort cable, left speaker, power supply, rear enclosure, right speaker, stand, Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

Note: Verify the issue after using the computer for a few
minutes to warm it, or by following steps in HT207571: Warm
a Mac for testing. Doing this may help identify intermittent
issues.

1. Use macOS Recovery to troubleshoot potential software

issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
2. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates. Remember that
third-party software can contribute to this issue. It may
be necessary to check for and apply third-party updates
that may not appear in the App store.
3. Remove all external devices, except for a known-good
USB keyboard and mouse, to help rule out peripherals
as a possible cause of this issue.
4. Verify memory configuration matches actual amount of
installed physical memory.
Computer displays a kernel panic alert message
5. Hold Shift key during startup to put computer into safe
Computer freezes during use
mode. See HT201262: Use safe mode to isolate issues
Computer freezes upon wake from sleep
with your Mac.
Computer freezes when Wi-Fi is enabled or activated
6. Follow steps outlined in article HT200553: If your Mac
Note: Inform user that computer failures due to accidental spontaneously restarts or displays a message that it
damage are not covered. If applicable, discuss out-of- restarted or shut down because of a problem.
warranty repair options. 7. If the issue cannot be easily reproduced, Run AST 2
extended memory tests, if available, repeatedly, to verify
that the computer does not encounter a crash or kernel
panic.

Warning: Be extremely careful when working inside the

computer when power is applied and the system energized.
Avoid touching the logic board or power supply while the
computer is plugged in. Always cover the power supply and
logic board with power supply covers to protect yourself when
working inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive
 Check Result Action Code Commodity
A voltage, current, or thermal Go to “Intermittent
sensor failure or an inoperative Shutdown”
fan can cause kernel panics or Yes troubleshooting ${nodeText.yesSymptomCode}
system crashes. Run Macintosh flow.
Resource Inspector (MRI) or
1. consult MRI logs to check for any
sensor or fan failures.
Go to step 2.
No ${nodeText.noSymptomCode}
Does MRI report any sensor or
fan failures?
Go to step 3.
Yes ${nodeText.yesSymptomCode}
Issue resolved by
SMC/NVRAM reset.
Verify resolution.

This issue could

Reset SMC using the procedure reoccur if the cause
listed for this computer in article is one of the user's
HT201295: How to reset the external devices
System Management Controller that was not
(SMC) on your Mac to return brought in with the
computer to a known power-off computer.
state. Try to turn on from power-
off state. Do not hold in the Advise user to verify
power button when turning on computer is
the computer. You could functioning properly
2. inadvertently put the computer by initially leaving
into DFU mode if you do. No all external devices ${nodeText.noSymptomCode}
detached, then
Then reset the NVRAM using the connecting them
procedure for this computer in one at a time to
article HT204063: How to Reset confirm each
NVRAM on your Mac. device's
functionality.

Does computer still experience If this issue

crashes or kernel panics? reoccurs, the user
should document
which external
devices are
attached and bring
them with the
computer.

Ask user which USB device(s) Go to step 4.

Yes ${nodeText.yesSymptomCode}
are used with computer when
crashes or kernel panics occur.
3.
Go to step 5.
No ${nodeText.noSymptomCode}
Does user have a USB device
that may be causing crashes or
kernel panics?
Go to step 5.
Yes ${nodeText.yesSymptomCode}

Connect a known-good Apple

wired keyboard and Apple wired
mouse to user's computer.
Disconnect user's USB
device(s). Test computer with ESCALATION
4.
OS or diagnostics. REQUIRED.
No ${nodeText.noSymptomCode}
Contact ACS for
Does computer still experience additional support
crashes or kernel panics? and latest USB
device information.
 Check Result Action Code Commodity
Connect a known-good Apple Go to step 6.
Yes ${nodeText.yesSymptomCode}
wired keyboard and Apple wired
mouse to user's computer.

Use macOS Recovery to

troubleshoot potential software
5. issues. Hold down Command-R
Go to step 9.
during startup to restart from the No ${nodeText.noSymptomCode}
recovery partition.

Does computer still experience

crashes or kernel panics?
Hold Shift key during startup to Go to step 7.
Yes ${nodeText.yesSymptomCode}
put computer into Safe Mode.
See article HT201262: Use safe
mode to isolate issues with your
6. Mac.
Go to step 10.
No ${nodeText.noSymptomCode}

Does computer still experience

crashes or kernel panics?
Turn off computer. Unplug Go to step 8.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding.

Remove display panel and logic

board to gain access to memory.
Isolate and replace
Remove all memory modules.
memory module.
While memory is removed, verify
that the memory is made by Note: Only replace
Apple, or third-party memory that a defective memory
7.
module. There is no
meets Apple specifications. No X01 MEMORY
Refer to HT205040: iMac need to replace
memory in pairs.
memory specifications for more
information.
Verify issue
resolved.
Substitute one by one with a
known-good memory module.

Reseat all memory modules

securely in their slots and retest.

Does computer still experience

crashes or kernel panics?
 Check Result Action Code Commodity
Check logic board memory slots Reinstall user's
one by one, using a known-good memory. Replace
memory module, to isolate a slot- logic board.
related failure and retest.
Use Blank Board
Note: Connecting an external Serializer (BBS) to
Yes M06 MLB
display will permit retesting set the computer’s
without reinstalling the internal serial number.
display panel.
Verify that the issue
Warning: HIGH VOLTAGE: The is resolved.
power supply remains
8.
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the Go to step 10.
No ${nodeText.noSymptomCode}
display panel removed.

Does crash or kernel panic occur

when memory is installed in a
specific slot?
Restore macOS on user's flash Replace the user's
storage. Refer to HT201260: flash storage. Verify
Yes H02 SSD
How to find the macOS version issue resolved.
number on your Mac to make
sure system build is correct for
9. this computer model. Check for
and apply the latest software and Issue resolved after
firmware updates. reinstalling macOS.
No ${nodeText.noSymptomCode}
Verify resolution.

Does computer still experience

crashes or kernel panics?
Turn off computer. Unplug Go to step 18.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding.

Remove display panel.

10.
Locate and disconnect the Go to step 11.
No ${nodeText.noSymptomCode}
camera/front microphone/ALS
cable from the logic board and
camera, and retest computer
with OS or diagnostics.

Does computer still experience

crashes or kernel panics?
Inspect both ends of the cable, Go to step 12.
Yes ${nodeText.yesSymptomCode}
the logic board connector, and
the camera connector for any
damage.
11.
Go to step 13.
No ${nodeText.noSymptomCode}
Is there any damage to the
camera/front microphone/ALS
cable or any connectors?
 Check Result Action Code Commodity
Replace the
camera/front
microphone/ALS
cable. INTERNAL
Yes X03
CABLE
Verify that the issue
Determine whether the damage is resolved.
is located on the camera/front
microphone/ALS cable, the logic
board, the camera, or a
combination of multiple
12. components.

ESCALATION
Is the damage limited to the REQUIRED.
camera/front microphone/ALS No X99
cable cable only? Contact ACS for
additional support
or a multiple-part
repair.

Reseat camera/front Go to step 14.

Yes ${nodeText.yesSymptomCode}
microphone/ALS cable securely
to logic board and camera.

Turn on computer and retest

computer with OS or diagnostics. Run AST 2
extended memory
Warning: HIGH VOLTAGE: The tests, if available,
power supply remains repeatedly to verify
energized whenever the that the computer
13.
computer is plugged in, does not encounter
No ${nodeText.noSymptomCode}
whether or not the computer a crash or kernel
has been turned on. Use panic.
extreme caution when
troubleshooting with the Verify that the issue
display panel removed. is resolved.

Does computer still experience

crashes or kernel panics?
Go to step 15.
To troubleshoot this issue Yes ${nodeText.yesSymptomCode}
completely, a known-good
Replace the
camera/front microphone/ALS
camera/front
cable is required.
microphone/ALS
14.
cable. INTERNAL
No X03
CABLE
Do you have immediate access
Verify that the issue
to a known-good camera/front
is resolved.
microphone/ALS cable?
Go to step 16.
Yes ${nodeText.yesSymptomCode}
Substitute a known-good
camera/front microphone/ALS Replace the
cable and retest computer with camera/front
OS or diagnostics. microphone/ALS
15.
cable. INTERNAL
No X03
CABLE
Does computer still experience Verify that the issue
crashes or kernel panics? is resolved.
 Check Result Action Code Commodity
The camera is part of the display Go to step 17.
Yes ${nodeText.yesSymptomCode}
panel in this model.
Replace display
To troubleshoot this issue panel, which
completely, a known-good includes the
16.
display panel is required. camera.
No L37 LCD
Verify issue
Do you have immediate access resolved.
to a known-good display panel?
Replace display
panel, which
includes the
camera.
Yes L37 LCD
Verify issue
Substitute a known-good display resolved.
panel and retest computer with
OS or diagnostics. Replace logic
17. board.

Does computer still experience Use Blank Board

crashes or kernel panics? Serializer (BBS) to
No set the computer’s M06 MLB
serial number.

Verify that the issue

is resolved.
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 23.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding.

Remove display panel and logic

board to gain access to flash
storage cards.

Disconnect and remove both

flash storage cards from the logic
board and reassemble the
computer. Note from which
connector (left or right) that each
flash storage card was removed.
The cards must be reinstalled
into the same connectors from
which they were removed, or the
computer will not start up. Do not
18.
mix up the flash storage cards. Go to step 19.
No ${nodeText.noSymptomCode}
Connect an Ethernet cable and
power cord to computer, wait five
seconds for SMC to reset, then
press power button. Hold down
Command-Option-R keys during
startup to force restart from
macOS Internet recovery.

This process may take a few

minutes for computer to
completely start up, depending
on speed of your Internet
connection. See article
HT201314: About macOS
Recovery for more information.

Does computer still experience

crashes or kernel panics?
To troubleshoot this issue Go to step 20.
Yes ${nodeText.yesSymptomCode}
completely, a known-good
matched pair of flash storage
modules is required.

Note: Flash storage in this model

is in two matched parts, and
must be installed properly or the
19.
computer will not start up. Refer Go to step 21.
No ${nodeText.noSymptomCode}
to service documentation for
more information.

Do you have immediate access

to a known-good flash storage
module pair?
 Check Result Action Code Commodity
Reinstall user's
flash storage.
Replace logic
Substitute known-good flash
storage with an up-to-date, board.
bootable version of macOS
installed. Refer to HT201260: Use Blank Board
Yes Serializer (BBS) to M06 MLB
How to find the macOS version
set the computer’s
number on your Mac to make
20. serial number.
sure system build is correct for
this computer model.
Verify that the issue
is resolved.
Does computer still experience
Replace user's flash
crashes or kernel panics?
storage. Verify
No H02 SSD
issue resolved.

Turn off computer. Unplug Issue resolved after

computer from AC mains by Disk Utility repair.
Yes ${nodeText.yesSymptomCode}
disconnecting both ends of its Verify resolution.
power cord. Ensure computer is
completely disconnected from
AC mains before proceeding.

Remove display panel and logic

board to gain access to flash
storage cards.

Reconnect flash storage cards to

logic board and reassemble the
computer. The cards must be
reinstalled into the same
connectors from which they were
removed, or the computer will
not start up.

Hold down Command-R during

21. startup to restart from the
recovery partition and use Disk
Go to step 22.
Utility to repair user’s flash No ${nodeText.noSymptomCode}
storage. If disk repair is
successful, restart and test
user’s OS.

Warning: HIGH VOLTAGE: The

power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Was Disk Utility repair successful

and is crash/kernel panic issue
resolved?
Restore macOS on user's flash Replace the user's
storage. Refer to HT201260: flash storage. Verify
Yes H02 SSD
How to find the macOS version issue resolved.
number on your Mac to make
sure system build is correct for
22. this computer model. Check for
and apply the latest software and Issue resolved after
firmware updates. reinstalling macOS.
No ${nodeText.noSymptomCode}
Verify resolution.

Does computer still experience

crashes or kernel panics?
 Check Result Action Code Commodity

Use extended version of Cooling

System Diagnostics (CSD) to
verify proper function of the
following subsystems: ESCALATION
REQUIRED.
SMC
Yes ${nodeText.yesSymptomCode}
Fan Contact ACS for
23.
Thermal sensors additional support
CPU–heat sink thermal or a multiple-part
interface repair.

Does computer pass all CSD

tests? Go to step 24.
No ${nodeText.noSymptomCode}
Turn off computer. Unplug Issue resolved by
computer from AC mains by cleaning fan and
disconnecting both ends of its heat sink and
power cord. Ensure computer is Yes reseating fan ${nodeText.yesSymptomCode}
completely disconnected from connections. Verify
AC mains before proceeding. resolution.

Remove display panel.

Remove all fan screws and

extract fan to reveal heat sink or
fan air duct. Use an ESD-safe
vacuum to remove dust or debris
from inner side of heat sink fin
stack. Clean fan rotor blades.
Reinstall fan and reseat fan
24. cable connections to logic board.
Reassemble and retest with
CSD.
Go to step 25.
No ${nodeText.noSymptomCode}
Warning: HIGH VOLTAGE: The
power supply remains
energized whenever the
computer is plugged in,
whether or not the computer
has been turned on. Use
extreme caution when
troubleshooting with the
display panel removed.

Does computer pass all CSD

checks?
To troubleshoot this issue Go to step 26.
Yes ${nodeText.yesSymptomCode}
completely, a known-good fan is
required.
25. Replace fan. Verify
OTHER
No issue resolved. X22
ELECTRIC
Do you have immediate access
to known-good fan?
 Check Result Action Code Commodity
Replace fan. Verify
OTHER
Yes issue resolved. X22
ELECTRIC
Reinstall user's fan.
Replace logic
Substitute a known-good fan and
board.
retest using MRI and CSD.
26. Use Blank Board
Serializer (BBS) to
Does computer now pass MRI No M06 MLB
set the computer’s
and CSD tests?
serial number.

Verify that the issue

is resolved.

Issue resolved.
Run AST 2 extended memory Yes ${nodeText.yesSymptomCode}
tests, if available, repeatedly to
verify that the computer does not
encounter a crash or kernel
panic

Run AST 2 Full System ESCALATION

27. Diagnostic (EFI & OS), if REQUIRED.
available, to ensure no other No ${nodeText.noSymptomCode}
issues remain. Contact ACS for
additional support
Verify that the issue is resolved. or a multiple-part
repair.

Is the issue resolved?

No Power
Unlikely causes:
Camera/microphone/ALS cable, fan, DisplayPort cable, display panel, left speaker, memory, right speaker, flash storage
card, stand, Wi-Fi/Bluetooth antenna(s)

Quick Check

Symptoms Quick Check

1. Verify AC power source.
2. Disconnect all peripherals.
3. Verify user’s power cord.
4. Determine whether computer is in power-on state by
checking for one or more of the following:

Fan spinning sound

Display backlight on
Any display activity

5. Follow suggested steps in HT204267: If your Mac won’t

turn on.
6. Reset SMC using the procedure listed for this computer
Computer does not turn on in article HT201295: How to reset the System
Computer does not turn off
Management Controller (SMC) on your Mac. Do not hold
No image on internal or external displays
in the power button when turning on the computer. You
No sounds from fan
could inadvertently put the computer into DFU mode if
No Caps Lock LED when key is pressed on wired
you do.
keyboard
Non-operational
Warning: Be extremely careful when working inside the
computer with power applied and the system energized. Avoid
Note: Inform user that computer failures due to accidental
touching the logic board or power supply while the computer
damage are not covered. If applicable, discuss out-of-
is plugged in. Always cover the power supply and logic board
warranty repair options.
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive

Check Result Action Code Commodity

The user may report that the Will Not
Go to step 21.
computer will not turn off or Turn ${nodeText.yesSymptomCode}
the computer will not turn on Off
(no power).
1.
No Go to step 2.
${nodeText.noSymptomCode}
Power
Which issue is the user
experiencing?
 Check Result Action Code Commodity
Connect AC power cord and Go to step 15.
Yes ${nodeText.yesSymptomCode}
press power button to start
up computer.

Check computer for any

signs of power activity, such
2.
as fan or Caps Lock LED on Go to step 3.
No ${nodeText.noSymptomCode}
wired keyboard.

Does computer show any

signs of power activity?
Inspect user’s power cord Go to step 4.
Yes ${nodeText.yesSymptomCode}
for wire or connector
damage. Also inspect
computer AC inlet for signs
of arcing or damaged pins,
3. which could affect power
Go to step 5.
cord connections. No ${nodeText.noSymptomCode}

Did you find any damaged

components?
Replace user’s power cord.
EXTERNAL
Yes Verify issue resolved. X03
CABLE
Determine whether damage
affects user’s power cord,
AC inlet, or both.
4.
No ESCALATION REQUIRED. ${nodeText.noSymptomCode}
Is damage limited to power
cord only?
Contact ACS for additional
support or a multiple-part repair.

Verify that user’s power Go to step 6.

Yes ${nodeText.yesSymptomCode}
cord is securely plugged into
a known-good, grounded
electrical outlet that provides
adequate voltage and power
to operate computer. Ensure
5. power cord is fully seated to
Go to step 15.
AC inlet. Attempt to turn on No ${nodeText.noSymptomCode}
computer.

Does issue persist after

reseating power cord?
Substitute a known-good Go to step 7.
Yes ${nodeText.yesSymptomCode}
power cord and attempt to
turn on computer.
6. Replace user’s power cord.
EXTERNAL
No Verify issue resolved. X03
CABLE
Does issue persist with
known-good power cord?
 Check Result Action Code Commodity
Reset SMC using the Go to step 8.
Yes ${nodeText.yesSymptomCode}
procedure listed for this
computer in article
HT201295: How to reset the
System Management
Controller (SMC) on your
Mac. Do not hold in the
7. power button when turning
Issue resolved after SMC reset.
on the computer. You could No Verify resolution. ${nodeText.noSymptomCode}
inadvertently put the
computer into DFU mode if
you do.

Does issue persist after

SMC reset?
Turn off computer. Unplug Go to step 9.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding and allow
the power supply and logic
board to discharge.

Remove display panel.

Disconnect, inspect and

reseat:

AC inlet power to
power supply
DC power cable
between power supply
and logic board
Power button cable to
logic board
8.
Go to step 10.
No ${nodeText.noSymptomCode}
Inspect wires and
connectors, looking for
pinched or exposed wire,
and burnt or damaged
connectors and pins.

Check all power supply bus

bars to ensure they are
tightly fastened to the logic
board. Follow service guide
procedures to tighten any
loose bus bars.

Also inspect the power

supply for any damage, such
as components that have
become loose or broken off.

Did you find any damaged

components?
 Check Result Action Code Commodity
DC power cable is part of power
supply.
Determine whether damage POWER
affects DC power cable only, Yes Replace power supply. P16
SUPPLY
or additional components
such as power supply or Verify that the issue is resolved.
logic board connectors.
Multiple damaged parts
9.
requiring replacement will be
escalated to ACS.

No ESCALATION REQUIRED. ${nodeText.noSymptomCode}

Is damage limited to DC
power cable only? Contact ACS for additional
support or a multiple-part repair.

Connect AC power cord and Go to step 15.

Yes ${nodeText.yesSymptomCode}
press power button to start
up computer.

Check computer for any

signs of power activity, such
as fan or Caps Lock LED on
wired keyboard.

Warning: HIGH VOLTAGE:

The power supply remains
energized whenever the
computer is plugged in,
whether or not the
computer has been turned
on. Use extreme caution
10. when troubleshooting with
Go to step 11.
the display panel removed. No ${nodeText.noSymptomCode}

For additional safety

information and tips, refer to
articles:

TP1620: iMac Pro

(2017): Power Supply
Cover Instructions
TP1637: iMac Pro
(2017): Safety

Does computer show any

signs of power activity?
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 12.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding and allow
the power supply and logic
board to discharge.

Remove display panel.

Locate diagnostic LEDs on

logic board. Connect AC
power cord. Press the
diagnostic button (near
diagnostic LEDs on logic
11. Replace power supply. Verify
board) to activate and view POWER
No issue resolved. P01
LEDs. Diagnostic LED #1 SUPPLY
should turn on.

This indicates that:

the AC power cord is

good
the power supply
signal cable connection
to the logic board is
good
power supply trickle
voltage is good

Is diagnostic LED #1 on?

Turn off computer. Unplug Go to step 13.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding and allow
the power supply and logic
board to discharge.

Disconnect power button

cable from logic board to ESCALATION REQUIRED.
inspect cable and connector
for damage. Using a Replace the rear enclosure
multimeter set as ohm which includes the power button
meter, verify continuity and cable. Verify issue resolved.
between the two pins of the
12. power button when it is Rear cover replacement is not
pressed. A properly working No normally covered by Apple’s ${nodeText.noSymptomCode}
power button should be open one-year limited warranty or the
(disconnected) when the AppleCare Protection Plan.
button is released and Refer to
closed (connected) when the www.apple.com/legal/warranty.
button is pressed.
If the power button issue was not
For additional information on caused by accidental damage,
using a multimeter, see then contact ACS for additional
HT3250: Using a digital support regarding warranty
multimeter. coverage for this part.

Does power button have

continuity when button is
pressed and open when
released?
 Check Result Action Code Commodity
Reconnect power button Go to step 14.
Yes ${nodeText.yesSymptomCode}
cable to logic board.

Connect AC power cord and

press power button to start
up computer.

Press the diagnostic button

(near diagnostic LEDs on
13. Replace power supply. Verify
logic board) to activate and POWER
No issue resolved. P01
view LEDs. Diagnostic LEDs SUPPLY
#1 and #2 should turn on.
This indicates power to
computer.

Are both diagnostic LED #1

and LED #2 on?
Check computer for any Go to step 15.
Yes ${nodeText.yesSymptomCode}
signs of power activity, such
as fan or Caps Lock LED on
wired keyboard.
14.
Go to step 17.
No ${nodeText.noSymptomCode}
Does computer show any
signs of power activity?
Verify whether a video signal Run Mac Resource Inspector
appears on display. (MRI) to obtain latest test
Yes ${nodeText.yesSymptomCode}
results. Verify issue resolved.
15.
Is a video image clearly Go to step 16.
No ${nodeText.noSymptomCode}
visible on display?
On a display with dim or no Go to “Backlight Issue / No
backlight, shine a bright Yes Backlight” troubleshooting flow. ${nodeText.yesSymptomCode}
flashlight onto front of
display while carefully
checking for a faint image
showing graphics, an Apple
16. logo, open windows, or other
Go to “Power But Blank/No
signs that the system is
No Video” troubleshooting flow. ${nodeText.noSymptomCode}
partially functional.

Is any video visible with

flashlight?
To continue to troubleshoot Go to step 18.
Yes ${nodeText.yesSymptomCode}
this issue, a known-good
power supply is required.
17.
Go to step 19.
No ${nodeText.noSymptomCode}
Do you have immediate
access to a known-good
power supply?
Important: Ensure that Replace power supply. Verify
POWER
user's computer is shut Yes issue resolved. P01
SUPPLY
down, then remove power
cord and wait two minutes
for self discharge to occur.

18. Substitute a known-good

power supply and attempt to Go to step 19.
No ${nodeText.noSymptomCode}
turn on computer.

Does computer show any

signs of power activity?
 Check Result Action Code Commodity
Important: Remove AC Replace coin cell battery.
power to computer and wait
two minutes. Note: Effective immediately,
some coin cell batteries used on
Measure the logic board coin Mac systems are now available
battery voltage. only from electronics parts
distributors (for example, MCM).
Refer to the service guide for The coin battery is no longer
information about locating available to order via
the RTC battery GSX. Please order this battery
measurement test pads. from an electronics parts
distributor.
OTHER
Carefully touch one Yes X32
ELECTRIC
multimeter probe to each Note: BR2032 and CR2032
pad to measure an expected batteries have the same form
19.
coin battery voltage of 3 factor and nominal voltage.
volts DC. However, BR2032 batteries
have a lower self-discharge rate
If the voltage is 2.7 VDC or and broader operating
less, replace the coin temperature range than CR2032
battery. batteries for longer shelf and
service life.
For additional information on
using a multimeter, see Verify that the issue is resolved.
HT3250: Using a digital
multimeter.
Go to step 20.
No ${nodeText.noSymptomCode}
Is the coin battery voltage
low (2.7 VDC or less)?
Follow service guide Issue resolved by resetting logic
procedures to force-reset the Yes board. Verify resolution. ${nodeText.yesSymptomCode}
logic board Real-Time Clock
(RTC).

Refer to the service guide for

information about locating
the RTC reset test pads and
performing the reset
procedure.

Be extra careful not to touch

any other components to
avoid damaging logic board.
Replace logic board.
Warning: Do not short-
circuit the reset pads for
20. Use Blank Board Serializer
more than a few seconds, as
(BBS) to set the computer’s
doing so may cause damage No M01 MLB
serial number.
to coin battery and/or logic
board.
Verify that the issue is resolved.
Connect AC power cord and
press power button to start
up computer.

Check computer for any

signs of power activity, such
as fan or Caps Lock LED on
wired keyboard.

Does computer show any

signs of power activity?
 Check Result Action Code Commodity
If any app hangs or freezes Issue cannot be duplicated.
Yes ${nodeText.yesSymptomCode}
when the computer is
shutting down, then try to
force quit that app. Also
21. check if any software
Go to step 22.
updates are in progress. No ${nodeText.noSymptomCode}

Does the computer turn off?

Press and hold down the Go to step 23.
Yes ${nodeText.yesSymptomCode}
power button for 10 seconds
or until user’s computer
22. powers off.
Go to step 24.
No ${nodeText.noSymptomCode}

Does the computer turn off?

Reset SMC using the
procedure listed for this
computer in article
HT201295: How to reset the
System Management Yes ESCALATION REQUIRED. ${nodeText.yesSymptomCode}
Controller (SMC) on your
Mac. Do not hold in the Contact ACS for additional
23. power button when turning support or a multiple-part repair.
on the computer. You could
inadvertently put the
computer into DFU mode if
you do. Issue resolved after SMC reset.
No Verify resolution. ${nodeText.noSymptomCode}

Does issue persist after

SMC reset?
 Check Result Action Code Commodity
Turn off computer. Unplug Go to step 25.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of
its power cord. Ensure
computer is completely
disconnected from AC mains
before proceeding and allow
the power supply and logic
board to discharge.

Remove display panel.

Disconnect, inspect and

reseat:

AC inlet power to
power supply
DC power cable
between power supply
and logic board
Power button cable to
logic board
24.
Go step 26.
No ${nodeText.noSymptomCode}
Inspect wires and
connectors, looking for
pinched or exposed wire,
and burnt or damaged
connectors and pins.

Check all power supply bus

bars to ensure they are
tightly fastened to the logic
board. Follow service guide
procedures to tighten any
loose bus bars.

Also inspect the power

supply for any damage, such
as components that have
become loose or broken off.

Did you find any damaged

components?
 Check Result Action Code Commodity

ESCALATION REQUIRED.

Replace the rear enclosure

which includes the power button
and cable. Verify issue resolved.
Determine whether damage
affects power button cable Rear cover replacement is not
only from main logic board to Yes normally covered by Apple’s ${nodeText.yesSymptomCode}
rear enclosure, or additional one-year limited warranty or the
components such as power AppleCare Protection Plan.
supply or logic board Refer to
connectors. Multiple www.apple.com/legal/warranty.
25.
damaged parts requiring
replacement will be If the power button issue was not
escalated to ACS. caused by accidental damage,
then contact ACS for additional
support regarding warranty
Is damage limited to power coverage for this part.
button cable only?

No ESCALATION REQUIRED. ${nodeText.noSymptomCode}

Contact ACS for additional

support or a multiple-part repair.
 Check Result Action Code Commodity
Turn off computer. Unplug No failure found during
computer from AC mains by diagnostic testing. Using correct
disconnecting both ends of positioning, return computer to
Yes ${nodeText.yesSymptomCode}
its power cord. Ensure user with no trouble found. Verify
computer is completely issue resolved.
disconnected from AC mains
before proceeding and allow
the power supply and logic
board to discharge.

Disconnect power button

cable from logic board to
inspect cable and connector
for damage. Using a
multimeter set as ohm
meter, verify continuity
between the two pins of the
power button when it is
pressed.

A properly working power

button should be open ESCALATION REQUIRED.
(disconnected) when the
button is released and Replace the rear enclosure
closed (connected) when the which includes the power button
26. button is pressed. and cable. Verify issue resolved.

A meter reading of 0 to 0.2 Rear cover replacement is not

(ohms) means that the No normally covered by Apple’s ${nodeText.noSymptomCode}
power button has continuity one-year limited warranty or the
(the button is closed or AppleCare Protection Plan.
connected). Refer to
www.apple.com/legal/warranty.
A meter reading of 0.2
(ohms) to (infinity) means If the power button issue was not
that the power button does caused by accidental damage,
not have continuity (the then contact ACS for additional
button is open or support regarding warranty
disconnected). coverage for this part.

For additional information on

using a multimeter, see
HT3250: Using a digital
multimeter.

Does power button have

continuity when button is
pressed and open when
released?
Verify that computer can Issue resolved.
Yes ${nodeText.yesSymptomCode}
now complete startup
process over multiple trials.

Run AST 2 Full System

Diagnostic (EFI & OS), if
available, to ensure no other
27.
issues remain.
No ESCALATION REQUIRED. ${nodeText.noSymptomCode}
Verify that the issue is
resolved. Contact ACS for additional
support or a multiple-part repair.

Is the issue resolved?

Will Not Start Up
Unlikely causes:
Camera/front microphone/ALS cable, fan, DisplayPort cable, left speaker, power supply, rear enclosure, right speaker, stand

Quick Check

Symptoms Quick Check

1. In the event that there is an iBridge / macOS version
mismatch in the user’s computer, iBridge firmware will
update automatically while the computer is connected to
the Internet. During this process the computer’s display
can remain completely black for some period of time (at
least 30 seconds). If the computer is turned off or
disconnected from the Internet during this process under
the assumption that something went wrong, the black
screen will occur again until the iBridge update has
completed. To resolve this issue, plug in the computer,
attempt to turn it on, then wait at least one minute to
provide an opportunity for any updates to complete if
needed. Once completed, the computer should display
video once again. For more information, see OP1935:
iMac Pro (2017) Service Readiness Guide.
2. After logic board replacement, if the computer turns on
but displays only a black screen and does not start up,
this could mean that the replacement logic board has
not yet been configured for use. For complete
instructions to configure a replacement logic board, refer
to TP1625: iMac Pro (2017): Using the Mac
Configuration Utility.
3. Use macOS Recovery to troubleshoot potential software
issues. Hold down Command-R during startup to restart
from the recovery partition. See article HT201314: About
macOS Recovery.
4. Refer to HT201260: How to find the macOS version
number on your Mac to make sure system build is
correct for this computer model. Check for and apply the
latest software and firmware updates. Remember that
third-party software can contribute to this issue. It may
be necessary to check for and apply third-party updates
that may not appear in the App store.
5. Verify that startup process passes initial memory checks
and POST (Power-On Self-Test) with some video
No display image appears during startup activity. If computer generates beeping sounds, there
Some video activity, Apple logo, progress indicator may be an issue with memory. See article HT201702:
Prohibitory sign or folder with a flashing question mark Intel-based Mac Power-On Self-Test RAM error codes.
Error beep tones 6. Remove all external devices, except for a known-good
Audible fan sounds USB keyboard and mouse, to help rule out peripherals
Caps Lock LED on wired keyboard toggles on and off as a possible cause of this issue.
when pressed 7. Follow suggested steps in HT206182: Helping
customers with a Mac that doesn't start up.
Note: Inform user that computer failures due to accidental 8. Verify memory configuration matches actual amount of
damage are not covered. If applicable, discuss out-of- installed physical memory.
warranty repair options. 9. Hold Shift key during startup to put computer into safe
mode. See HT201262: Use safe mode to isolate issues
with your Mac.
10. Reset SMC using the procedure listed for this computer
in article HT201295: How to reset the System
Management Controller (SMC) on your Mac to return
computer to a known power-off state. Try to turn on from
power-off state. Do not hold in the power button when
turning on the computer. You could inadvertently put the
computer into DFU mode if you do.
11. Reset the NVRAM using the procedure for this computer
in article HT204063: How to Reset NVRAM on your Mac.
12. Run Disk Utility or check Mac Resource Inspector (MRI)
results to verify presence and SMART status of user’s
flash storage.
 13. Identify when during startup process computer hangs in
order to isolate the issue. See article HT204156: About
the screens you see when your Mac starts up.

Warning: Be extremely careful when working inside the

computer with power applied and the system energized. Avoid
touching the logic board or power supply while the computer
is plugged in. Always cover the power supply and logic board
with power supply covers to protect yourself when working
inside the computer.

Before removing any components, be sure to turn off

computer, and unplug computer from AC mains by
disconnecting both ends of its power cord. Ensure computer is
completely disconnected from AC mains before proceeding.

For additional safety information and tips, refer to articles:

TP1620: iMac Pro (2017): Power Supply Cover

Instructions
TP1637: iMac Pro (2017): Safety

Deep Dive

Check Result Action Code Commodity

A memory error is indicated by a Go to step 11.
Yes ${nodeText.yesSymptomCode}
sequence of one or three beep
tones. Refer to article HT201702:
Intel-based Mac Power-On Self-
Test RAM error codes for more
1.
information. Go to step 2.
No ${nodeText.noSymptomCode}

Does computer make error beep

tones at startup?
Connect AC power cord and Go to step 3.
Yes ${nodeText.yesSymptomCode}
press power button to start up
computer.

Press the diagnostic button (near

diagnostic LEDs on logic board)
to activate and view LEDs.
2.
Diagnostic LED # 3 should turn Go to step 11.
No ${nodeText.noSymptomCode}
on. This indicates that memory is
functioning.

Is the diagnostic LED #3

illuminated?
Observe startup process to verify Go to step 4.
Yes ${nodeText.yesSymptomCode}
that the computer displays an
image. Go to “Power But
3. Blank/No Video”
No troubleshooting ${nodeText.noSymptomCode}
Does the computer display an flow.
image during startup process?
 Check Result Action Code Commodity
Issue cannot be
duplicated.

If the user reports

Verify that computer completes that the issue is
full startup process: Apple logo > intermittent, repeat
progress indicator > login screen steps 2 through 4
Yes ${nodeText.yesSymptomCode}
> user's desktop. multiple times to
4.
confirm
functionality before
Does computer complete startup returning the
process to user's desktop? computer to the
user.

Go to step 5.
No ${nodeText.noSymptomCode}
Go to “Kernel
Start up computer and determine
Panic/System
whether a kernel panic is
Crashes”
occurring. Yes ${nodeText.yesSymptomCode}
troubleshooting
5.
flow.
Does computer display a kernel
Go to step 6.
panic during startup? No ${nodeText.noSymptomCode}
Connect a known-good Apple Go to step 9.
Yes ${nodeText.yesSymptomCode}
wired keyboard and Apple wired
mouse to user's computer.

Use macOS Recovery to

troubleshoot potential software
6. issues. Hold down Command-R
Go to step 7.
during startup to restart from the No ${nodeText.noSymptomCode}
recovery partition.

Does computer start up from

recovery partition?
Restore macOS on user's flash Go to step 8.
Yes ${nodeText.yesSymptomCode}
storage. Refer to HT201260:
How to find the macOS version
number on your Mac to make
sure system build is correct for Replace the user's
7. this computer model. Check for flash storage.
and apply the latest software and No Verify issue H02 SSD
firmware updates.
resolved.

Does computer start up from

recovery partition?
Issue resolved
Verify that computer completes after reinstalling
full startup process: Apple logo > Yes macOS. Verify ${nodeText.yesSymptomCode}
progress indicator > login screen resolution.
> user's desktop.
8.
Replace the user's
flash storage.
Does computer complete startup No Verify issue H02 SSD
process to user's desktop? resolved.
 Check Result Action Code Commodity
Replace coin cell
battery.

Note: Effective
immediately, some
coin cell batteries
used on Mac
Important: Remove AC power to
systems are now
computer and wait two minutes.
available only from
electronics parts
Measure the logic board coin
distributors (for
battery voltage.
example, MCM).
The coin battery is
Refer to the service guide
no longer available
‘Diagnostic LEDs and Test
to order via
Pads’ article for information
GSX. Please order
about locating the RTC battery
this battery from
measurement test pads.
an electronics
parts distributor.
Carefully touch one multimeter OTHER
Yes X32
probe to each pad to measure an ELECTRIC
9. Note: BR2032 and
expected coin battery voltage of 3
CR2032 batteries
volts DC.
have the same
form factor and
If the voltage is 2.7 VDC or less,
nominal voltage.
replace the coin battery.
However, BR2032
batteries have a
For additional information on
lower self-
using a multimeter, see article
discharge rate and
HT3250: Using a digital
broader operating
multimeter.
temperature range
than CR2032
batteries for longer
Is the coin battery voltage low
shelf and service
(2.7 VDC or less)? life.

Verify that the

issue is resolved.

Go to step 10.
No ${nodeText.noSymptomCode}
 Check Result Action Code Commodity
Follow service guide procedures Issue resolved by
to force-reset the logic board resetting logic
Real-Time Clock (RTC). Yes board. Verify ${nodeText.yesSymptomCode}
resolution.
Refer to the service guide for
information about locating the
RTC reset test pads and
performing the reset procedure.

Be extra careful not to touch any

other components to avoid
damaging logic board.
Replace logic
Warning: Do not short-circuit the board.
reset pads for more than a few
10. seconds, as doing so may cause Use Blank Board
damage to coin battery and/or Serializer (BBS)
logic board. to set the
No M02 MLB
computer’s serial
Connect AC power cord and number.
press power button to start up
computer. Verify that the
issue is resolved.
Check computer for any signs of
power activity, such as fan or
Caps Lock LED on wired
keyboard.

Does computer show any signs

of power activity?
Turn off computer. Unplug Go to step 12.
Yes ${nodeText.yesSymptomCode}
computer from AC mains by
disconnecting both ends of its
power cord. Ensure computer is
completely disconnected from AC
mains before proceeding.

Remove display panel and logic

board to gain access to memory.

Remove all memory modules.

While memory is removed, verify Issue resolved by

11. reseating memory.
that the memory is made by
Apple, or third-party memory that No ${nodeText.noSymptomCode}
Verify resolution.
meets Apple specifications. Refer
to HT205040: iMac memory
specifications for more
information.

Reseat all memory modules

securely in their slots and retest.

Does computer make error beep

tones at startup?
Typical configurations ship with Go to step 14.
Yes ${nodeText.yesSymptomCode}
two memory modules located in
first two slots. It is possible to see
a configuration with four memory
modules installed.
12.
Go to step 13.
No ${nodeText.noSymptomCode}
Is user's computer configured
with four memory modules
installed?
 Check Result Action Code Commodity
Keep track of where memory is Go to step 18.
Yes ${nodeText.yesSymptomCode}
located as you work in pairs to
isolate memory and later verify
slot functionality. Remove user
memory from second two slots
13. and retest.
Go to step 14.
No ${nodeText.noSymptomCode}

Does computer indicate a

memory error with user memory
in first two slots only?
Replace logic
board.
Leave user memory installed in
Use Blank Board
first two slots. Install two known-
Serializer (BBS)
good memory modules in second
to set the
two slots and retest. Yes M07 MLB
computer’s serial
14.
number.
Does computer indicate a
Verify that the
memory error with known-good
issue is resolved.
memory in second two slots?
Go to step 15.
No ${nodeText.noSymptomCode}
Leave the known-good memory Go to step 17.
Yes ${nodeText.yesSymptomCode}
pair in second two slots.

Remove user memory from first

two slots and set aside as
proven-good user memory.
15.
Install the original user memory Go to step 16.
No ${nodeText.noSymptomCode}
into first two slots. Retest.

Does computer indicate a

memory error with original user
memory in first two slots?

Leave memory in first two slots ESCALATION

as is. REQUIRED.

Remove known-good memory Contact ACS for

from second two slots. additional support. M99
Yes
Install proven-good user memory Situation: User
(previously set aside) into second memory passes
16.
two slots. test when paired
with known-good
Restart computer to verify user memory but fails
memory. when paired with
like user memory.

Does computer indicate a Issue resolved by

memory error with user memory? reconfiguring and
reseating memory.
No ${nodeText.noSymptomCode}
Verify resolution.
 Check Result Action Code Commodity
Go to step 18.
Yes ${nodeText.yesSymptomCode}

Remove known-good memory ESCALATION

from second two slots, leaving REQUIRED.
user memory in first two slots.
Restart computer to verify user Contact ACS for
memory in first two slots as additional support.
standalone with no memory in
17.
second two slots. Situation: User
No M99
memory (currently
located first two
Does computer indicate a slots) fails when
memory error with user memory paired with known-
in first two slots only? good memory and
passes when
known-good
memory is
removed from
adjacent slots.

Go to step 19.
Yes ${nodeText.yesSymptomCode}
Replace defective
Remove user memory module memory.
from first slot and substitute a
known-good memory module into Note: You may not
same first slot. Retest. return non-Apple
memory as KBB.
18.
Please verify
No X02 MEMORY
Does computer indicate a Apple memory
memory error with one known- using MRI before
good and one user module in first returning to Apple.
two slots?
Verify issue
resolved.

Keep known-good memory Replace logic

module in first slot and substitute board.
second slot module with a
second known-good memory Use Blank Board
module. Keep track of suspect Serializer (BBS)
user memory removed from to set the
Yes M07 MLB
second slot. Testing both first two computer’s serial
slots with known-good memory number.
19.
will verify error is either defective
slots or defective memory. Verify that the
issue is resolved.

Does computer indicate a

memory error using two known- Go to step 20.
No ${nodeText.noSymptomCode}
good memory modules in first two
slots?
 Check Result Action Code Commodity
Replace both user
memory modules
in first two slots.

Note: You may not

return non-Apple
memory as KBB.
Yes Please verify X02 MEMORY
Apple memory
using MRI before
Install first user memory module returning to Apple.
(removed from first slot) into
second memory slot and test Verify issue
paired with a known-good resolved.
20. memory module still in first slot.
Replace defective
memory.
Does computer indicate a
memory error? Note: You may not
return non-Apple
memory as KBB.
Please verify
No X02 MEMORY
Apple memory
using MRI before
returning to Apple.

Verify issue
resolved.

Issue resolved.
Verify that computer can now Yes ${nodeText.yesSymptomCode}
complete startup process over
multiple trials.

Run ASD or AST 2 Full System

Diagnostic (EFI & OS), if
21. available, to ensure no other ESCALATION
issues remain. No REQUIRED. X99

Verify that the issue is resolved. Contact ACS for

additional support
or a multiple-part
Is the issue resolved? repair.
About Apple service certifications

Topic
To learn more about accessing ATLAS and service exams, review these articles:

How to get a Tech ID

ATLAS frequently asked questions
How to access Apple service exams at Pearson VUE

Note: Apple Retail Store employees must read Understanding Exam and Certification requirements (RS228), in addition to
this procedure.

Exams and courses that you need to service iOS products

Training for Apple Certified iOS Technician (ACiT) 2018 is available to technicians who work at Apple-authorized
service facilities. Technicians need a Global Service Exchange (GSX) account to see the courses in ATLAS.

To register for any ACiT exam, use Pearson VUE.

ACiT 2018 certification

With ACiT 2018 certification, you can service iOS devices such as iPhone and iPad after passing the
following exams:

Apple Service Fundamentals Exam (SVC-18A) or (SVC-17A)

ACiT 2018 iOS Service Certification Exam (iOS-18A)

ACiT 2017 certification

Important: If you are not already ACiT 2017 certified, complete the ACiT 2018 exam instead.

With ACiT 2017 certification, you can service iPhone, iPad, Apple Watch and Apple TV devices after
passing the following exams:

Apple Service Fundamentals Exam (SVC-17A)

ACiT 2017 iOS Service Certification Exam (iOS-17A)

Please note that the following devices have additional requirements:

iPad Pro (12.9-inch) (2nd Generation), iPad Pro (10.5-inch), iPad Pro (9.7-inch), iPad Pro, iPad
(5th Generation), iPad (6th Generation) and iPad mini 4
Also complete the Troubleshooting iPad course in ATLAS.
iPhone 8 and iPhone 8 Plus
Also complete the Servicing iPhone 8 and 8 Plus course in ATLAS.
iPhone X
Also complete the Servicing iPhone X course in ATLAS

ACiT 2016 certification

With ACiT 2016 certification, you can service iPhone, iPad, Apple Watch and Apple TV devices after
passing these exams:

Apple Service Fundamentals Exam (SVC-16A)

ACiT 2016 iOS Service Certification Exam (iOS-16A)

Please note that the following devices have additional requirements:

iPad Pro (12.9-inch) (2nd Generation), iPad Pro (10.5-inch), iPad Pro (9.7-inch), iPad Pro, iPad
(5th Generation), iPad (6th Generation) and iPad mini 4
Also complete the Troubleshooting iPad course in ATLAS.
iPhone 7, iPhone 7 Plus
Also complete the Servicing iPhone 7 and iPhone 7 Plus course in ATLAS.
iPhone 8 and iPhone 8 Plus
Also complete the Servicing iPhone 8 and 8 Plus course in ATLAS.
iPhone X
Also complete the Servicing iPhone X course in ATLAS

Exams and courses that you need to service Mac products

Training for Apple Certified Mac Technician (ACMT) 2018 is available to technicians who work at Apple-
authorized service facilities. Technicians need a Global Service Exchange (GSX) account to view the courses in
ATLAS. To register for any ACMT exam, use Pearson VUE.

ACMT 2018 certification

With ACMT 2018 certification, you can service Mac computers after passing these exams:

Apple Service Fundamentals Exam (SVC-18A) or (SVC-17A)

ACMT 2018 Mac Service Certification Exam (MAC-18A)

ACMT 2017 certification

Important: If you're not already ACMT, ACMT 2015, ACMT 2016 or ACMT 2017 certified, complete
the ACMT 2018 exams instead.

With ACMT 2017 certification, you can service most Mac computers after passing these exams:

Apple Service Fundamentals Exam (SVC-17A)

ACMT 2017 Mac Service Certification Exam (MAC-17A)

These computers have additional requirements:

MacBook (Retina, 12-inch, 2017):

Also complete the MacBook (Retina, 12-inch, 2017), Trackpad Calibration Check and
Interpreting Liquid Contact Indicators (LCIs) courses in ATLAS
MacBook Air (11-inch, Mid 2013, Early 2014, and Early 2015) and MacBook Air (13-inch, Mid
2013, Early 2014, and 2017):
Also complete the MacBook Air course in ATLAS.
MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports) and MacBook Pro (15-inch, 2017):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016, Two Thunderbolt 3 Ports) and MacBook Pro (13-inch, 2017, Two
Thunderbolt 3 Ports):
Also complete the MacBook Pro with Two Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
iMac Pro (2017):
Also complete the Servicing iMac Pro (2017) course in ATLAS
iMac (2017):
Also complete the iMac (2017) course in ATLAS

ACMT 2016 certification

If you're not already ACMT 2016 certified, complete the ACMT 2018 exams instead.

With ACMT 2016 certification, you can service most Mac computers (some have additional
requirements) after passing these exams:

Apple Service Fundamentals Exam (SVC-16A)

ACMT 2016 Mac Service Certification Exam (MAC-16A)

These computers have additional requirements:

MacBook (Retina, 12-inch, 2017):

Also complete the MacBook (Retina, 12-inch, 2017), Trackpad Calibration Check, and
Interpreting Liquid Contact Indicators (LCIs) courses in ATLAS
MacBook (Retina,12-inch, Early 2016):
Also complete the MacBook (Retina, 12-inch, Early 2016) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS.
MacBook Air (11-inch, Mid 2013, Early 2014, and Early 2015) and MacBook Air (13-inch, Mid
2013, Early 2014, Early 2015, and 2017)
Also complete the MacBook Air course in ATLAS
MacBook Pro (15-inch, 2016 and 2017):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Four Thunderbolt 3 Ports):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Two Thunderbolt 3 Ports):
Also complete the MacBook Pro with Two Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
 iMac Pro (2017):
Also complete the Servicing iMac Pro (2017) course in ATLAS
iMac (2017):
Also complete the iMac (2017) course in ATLAS
iMac (Late 2015):
Also complete the iMac (Late 2015) course in ATLAS.

ACMT 2015 certification

If you're not already ACMT 2015 certified, complete the ACMT 2018 exams and courses instead.

With ACMT 2015 certification, you can service many Mac computers (some have additional
requirements) if you passed these exams:

OS X Yosemite Troubleshooting Exam (9L0-066)

Mac Hardware Service Exam (9L0-012)

These computers have additional requirements:

MacBook (Retina, 12-inch, 2017):

Also complete the MacBook (Retina, 12-inch, 2017), Trackpad Calibration Check, and
Interpreting Liquid Contact Indicators (LCIs) courses in ATLAS
MacBook (Retina, 12-inch, Early 2016):
Also complete the MacBook (Retina, 12-inch, Early 2016) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS.
MacBook (Retina, 12-inch, Early 2015):
Also complete the MacBook (Retina, 12-inch, Early 2015) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS
MacBook Air (11-inch, Mid 2013, Early 2014, and Early 2015) and MacBook Air (13-inch, Mid
2013, Early 2014, Early 2015 and 2017):
Also complete the MacBook Air course in ATLAS
MacBook Pro (15-inch, 2016 and 2017):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Four Thunderbolt 3 Ports):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Two Thunderbolt 3 Ports):
Also complete the MacBook Pro with Two Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (Retina, 13-inch, Early 2015):
Also complete the MacBook Pro 13-inch (2012 to 2015) course in ATLAS
MacBook Pro (Retina, 15-inch, Mid 2015):
Also complete the MacBook Pro 15-inch (2012 to 2015) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS
iMac Pro (2017):
Also complete the Servicing iMac Pro (2017) course in ATLAS
iMac (2017):
Also complete the iMac (2017) course in ATLAS
iMac (Late 2015):
Also complete the iMac (Late 2015) course in ATLAS.

ACMT certification

If you're not already ACMT certified, complete the ACMT 2018 exams and courses instead.

With ACMT certification, you can service certain Mac computers (some have additional requirements)
after passing these exams:

Mac OS X Mavericks Troubleshooting Exam (9L0-065)

Mac Hardware Service Exam (9L0-011)

These computers have additional requirements. (Some of these exams and courses are not currently
available.)

MacBook (Retina, 12-inch, 2017):

Also complete the MacBook (Retina, 12-inch, 2017), Trackpad Calibration Check, and
Interpreting Liquid Contact Indicators (LCIs) courses in ATLAS
MacBook (Retina, 12-inch, Early 2016):
Also complete the MacBook (Retina, 12-inch, Early 2016) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS.
MacBook (Retina, 12-inch, Early 2015):
 Also complete the MacBook (Retina, 12-inch, Early 2015) course in ATLAS, and the
Trackpad Calibration Check course in ATLAS
MacBook Air (11-inch, Mid 2013, Early 2014, and Early 2015) and MacBook Air (13-inch, Mid
2013, Early 2014, Early 2015 and 2017):
Also complete the MacBook Air course in ATLAS
MacBook Pro (15-inch, 2016 and 2017):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Four Thunderbolt 3 Ports):
Also complete the MacBook Pro with Four Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (13-inch, 2016 and 2017, Two Thunderbolt 3 Ports):
Also complete the MacBook Pro with Two Thunderbolt 3 Ports course in ATLAS and the
Trackpad Calibration Check course in ATLAS
MacBook Pro (Retina, 15-inch, Mid 2015):
Also complete the MacBook Pro 15-inch (2012-2015) course in ATLAS, and the Trackpad
Calibration Check course in ATLAS
MacBook Pro (Retina, 13-inch, Late 2012 to Early 2015):
Also complete the MacBook Pro 13-inch (2012 to 2015) course in ATLAS
MacBook Pro (Retina, Mid 2012) and MacBook Pro (Retina, 15-inch, Early 2013 to Mid 2014):
Also complete the MacBook Pro 15-inch (2012 to 2015) course in ATLAS
iMac Pro (2017):
Also complete the Servicing iMac Pro (2017) course in ATLAS
iMac (2017):
Also complete the iMac (2017) course in ATLAS
iMac (Late 2015):
Also complete the iMac (Late 2015) course in ATLAS.
iMac (Late 2012 to Mid 2015 models)
Also complete the iMac (2012 to 2015) course in ATLAS.
Mac Pro (Late 2013):
Also complete the Mac Pro (Late 2013) course in ATLAS

About the Apple Service Fundamentals Exam (SVC-18A)

The Apple Service Fundamentals Exam (SVC-18A) is a computer-based knowledge text that Pearson VUE offers
online. The test is open resource and test takers should use Apple references and courses in ATLAS to help
answer the exam items.

Successful completion of this exam fulfills the prerequisite for Apple Certified iOS Technician (ACiT) 2018
certification and Apple Certified Mac Technician (ACMT) 2018 certification. The SVC-18A exam must be
successfully completed before taking the Mac or iOS certification exams.

Exam summary

Number of sections: 5
Number of learning objectives: 34
Number of total items: 70
Passing score: 80 percent overall (at least 56 out of 70 items to pass)
Exam time limit: 2 hours

Seven demographic questions are presented at the beginning of the exam. These items aren't scored
and don't use the 2 hours given for the exam.

Two separately scored sections must be passed

The exam has two separately-scored sections that each must be passed to pass the entire exam. This
is in addition to the overall passing score listed above. The two sections are listed below:

The ESD Precautions section (at least 10 out of 12 questions answered correctly to pass)
The Safety section (at least 10 out of 12 questions answered correctly to pass)

Sections and topics

Here are the sections and topics covered in Apple Service Fundamentals Exam:

Customer Experience (23 items)

Identify the probing skills that result in getting good information from the customer
Select good examples of reflecting and summarizing the customer's answers in order to come to
agreement on the issue
Identify ways to properly position a repair so that the customer knows why it is necessary and is
 in agreement with the strategy
Identify ways to position and recommend upgrades and attachments as part of an alternative
service strategy.
Demonstrate use of the “Positive No” in a series of choose-the-phrase exercises
List practical applications of the four cornerstones of adult learning
Describe the effect of both complex technical language and over-simplified language
Identify good examples of phrases to help set accurate customer expectations
Describe the role of empathy in customer satisfaction
Identify ways to avoid conflict by using genuine empathy
Identify causes for conflict in an interaction
Identify the five-step anger diffusion technique given a customer scenario
Assess and explain the impact of non-verbal communication

ESD Precautions (12 items)

Correctly identify and practice ESD precautions

Correctly identify the components of an ESD-compliant workstation
Use the proper tools, equipment, and procedures to configure a workspace that minimizes or
eliminates the occurrence of electrostatic discharge damage
Correctly identify the effects of ESD damage on an integrated circuit
Correctly identify common ESD myths and why they are not true

Safety (12 items)

Identify those customer statements that will generate a Safety First issue
Explain the importance of exercising special care when handling lithium-ion/polymer batteries
Demonstrate the proper and safe handling of batteries
Recognize and identify signs and symptoms of damaged batteries
Respond to events involving embedded batteries

Troubleshooting (8 items)

Identify the different stages of troubleshooting and service where diagnostic tools are useful
List the components of clear, concise and complete case notes
Demonstrate basic troubleshooting and deductive reasoning skills
Use smart questioning techniques and first-level evaluation and isolation skills to identify issues
as being generally hardware based, software based, educational, or environmental in nature

Product Knowledge (15 items)

List and understand basic iOS controls and navigation

Identify the components of the default macOS user environment
List Apple Watch controls and Navigation
Given a customer scenario, evaluate, isolate, and resolve an Apple ID related issue
List the steps to configure Continuity services in macOS and in iOS
Describe how to configure a Bluetooth device in an Apple product
Identify the methods for backing up and restoring data on an Apple product

Courses in ATLAS

To prepare for the Apple Service Fundamentals Exam, we suggest that you review the courses in the
2018 Service Fundamentals subject area in ATLAS. The list of courses in the suggested order can be
found in 2018 Service Fundamentals.

About the ACiT 2018 iOS Service Certification Exam (iOS-18A)

The ACiT 2018 iOS Service Certification Exam is a computer-based knowledge test that Pearson VUE offers
online. This is an-open-resource test. We encourage you to use Apple references and courses in ATLAS to
answer the questions.

To earn Apple Certified iOS Technician (ACiT) 2018 certification, you need to pass this exam (iOS-18A) and the
Apple Service Fundamentals Exam (SVC-18A).

Please note: The Apple Service Fundamentals Exam must be taken before you take the iOS Service
Certification Exam.

Exam summary

Number of sections: 2
Number of learning objectives: 18
Number of total items: 70
 Passing score: 80 percent overall (at least 56 out of 70 items to pass)
Exam time limit: 2 hours

Seven demographic questions are presented at the beginning of the exam. These items aren't scored
and don't use the 2 hours given for the exam.

Sections and topics

Here are the sections and topics covered in ACiT Exam:

Troubleshooting (38 items)

Describe the diagnostics used in troubleshooting a given scenario

Given an isolated issue, categorize the issue as either hardware (including accidental damage),
software, environmental, or educational opportunity
Order the steps in the iOS setup and activation process
List common resolutions for battery-related issues
Identify basic controls for mailbox management
Describe the built-in apps and features of iOS
Describe how to personalize and customize iPhone General and Accessibility settings
Describe the privacy settings that can be put in place for apps

Servicing iPhone (32 items)

Identify the physical supplies and online resources necessary to ensure proper and safe
servicing of an iPhone model
Given a simulated workstation, identify the supplies that are necessary to reduce the possibility
of being harmed while servicing iPhone
Identify the tools that are commonly used to service all iOS models
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 5s
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 5c
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 6 and
iPhone 6 Plus
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 6s and
iPhone 6s Plus
Identify the correct specialized tools, fixtures, and procedures required to service iPhone SE
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 7 and
iPhone 7 Plus
Identify the correct specialized tools, fixtures, and procedures required to service iPhone 8 and 8
Plus
Identify the correct specialized tools, fixtures, and procedures required to service iPhone X

Courses in ATLAS

To prepare for the ACiT 2018 iOS Service Certification Exam (iOS-18A), we suggest that you review
the courses in the ACiT 2018 subject area in ATLAS. The list of courses in the suggested order can
be found in ACiT 2018 Overview.

About the ACMT 2018 Mac Service Certification Exam (MAC-18A)

The ACMT 2018 Mac Service Certification Exam (MAC-18A) is a computer-based knowledge test that Pearson
VUE offers online. This is an open-resource test. We encourage you to use Apple references and courses in
ATLAS to answer the questions.

To earn Apple Certified Mac Technician (ACMT) 2018 certification, you need to pass this exam (MAC-18A) and
the Apple Service Fundamentals Exam (SVC-18A).

Please note: You must complete the Apple Service Fundamentals Exam before you take the Mac Service
Certification Exam.

Exam summary

Number of sections: 2
Number of learning objectives: 28
Number of total items: 70
Passing score: 80 percent overall (at least 56 out of 70 items to pass)
Exam time limit: 2 hours

Seven demographic questions are presented at the beginning of the exam. These items aren't scored
and don't use the 2 hours given for the exam.
 Sections and topics

Here are the sections and topics covered in ACMT Exam:

Troubleshooting (36 items)

Evaluate and isolate file system issues with macOS-based systems

Given a network related customer issue, accurately evaluate, isolate and resolve the issue
Correctly identify the diagnostic tool most appropriate to a given troubleshooting scenario
Describe how to use troubleshooting tools and related procedures
Identify potential startup issues and associated fixes
Identify macOS migration tools needed for migration, the types of user data that can be
migrated, and the correct methods for migrating user data from both a Mac and PC
Identify the symptoms that are a result of an SMC that is not functioning correctly
Explain how to maximize the battery life of an Apple product
Identify the process to create, configure, manage, and delete user accounts in macOS
Configure FileVault 2 in macOS to secure the data on a Mac
Describe the data privacy concerns that are presented when Location Services is enabled in
macOS
Describe the method for resetting a lost Firmware (EFI) password
Describe how to use Time Machine in macOS to create, restore, and manage a secure data
backup

Repairing the Mac Family (34 items)

Given a simulated workstation, identify the supplies that are necessary to reduce the possibility
of damaging the customer's Mac while servicing the computer
Given a simulated workstation, identify the supplies that are necessary to reduce the possibility
of being harmed while servicing Mac models
Demonstrate the proper and safe handling of batteries and portable computer case assemblies
with built-in battery
Identify specialized tools, fixtures or procedures required to service iMac
Identify safety precautions necessary to safely service iMac models
Identify specialized tools, fixtures or procedures required to service iMac Pro
Identify safety precautions necessary to safely service iMac Pro models
Identify specialized tools, fixtures or procedures required to service Mac mini
Identify specialized tools, fixtures or procedures required to service MacBook Pro 13-inch
models
Identify internal connector types for specific MacBook Pro 13-inch models
Identify specialized tools, fixtures or procedures required to service MacBook Pro 15-inch
models
Identify internal connector types for specific MacBook Pro 15-inch models
Identify specialized tools, fixtures or procedures required to service MacBook Air
Identify specialized tools, fixtures or procedures required to service Mac Pro
Identify internal connector types for specific Mac Pro models
Identify safety precautions necessary to safely service Mac Pro models
Identify specialized tools, fixtures or procedures required to service MacBook

Courses in ATLAS

To prepare for the ACMT 2018 Mac Service Certification Exam (MAC-18A), we suggest that you
review the courses in the ACMT 2018 subject area in ATLAS. The list of courses in the suggested
order can be found in ACMT 2018 Overview.

Frequently Asked Questions

Can anyone take the service certification exams?

Yes. Anyone can take the exams to become an Apple Certified Mac Technician (ACMT) 2018 or Apple Certified
iOS Technician (ACiT) 2018. To pass these exams, you need to have access to the training in ATLAS.

Successfully completing the exams doesn't mean that Apple has authorized you to perform repairs or to conduct
business directly with Apple or on Apple's behalf. Apple certifies (verifies the skills of) technicians. Apple
authorizes (establishes business relationships with) service providers. These two things aren't the same.

How do I register for the exams?

Go to certifications.apple.com to register and create a Tech ID. Then use your Tech ID to register at an Apple
Authorized Training Center or online with Pearson VUE. After you've taken an Apple certification exam, you can
track and manage all of your Apple certifications at the certifications website.
How do I prepare for the service certification exams?

Apple provides self-paced training courses in ATLAS through Global Service Exchange (GSX). Apple Authorized
Service Providers (AASPs) and Self-Servicing Accounts (SSAs) can get the Service Training curriculum online for
free.

The Apple Service Fundamentals Exam (SVC-18A) has sections on ESD precautions and technician safety. You
must pass these sections in order to pass the exam as a whole.

If I don't pass an exam, how soon can I retake it?

You can retake an exam 24 hours after completing the last attempt.

How do I pay for the exams?

When you register for the certification exams, you can pay with Visa, MasterCard, or American Express.

Where can I verify my exams or certification status?

To verify your exam and certification status, go to certifications.apple.com. In the "Certification" tab, look for the
corresponding Certification Name in "My Certifications" and verify that the status is "Certified". To view exam
details, click the relevant Certification Name.

I checked my certification status at certifications.apple.com and it is "In Progress". What does that
mean?

If your certifications status is " In Progress", it signifies that not all requirements for the certification were
completed. To achieve "Certified" status, some certifications require one or more additional courses or exams to
be completed.

I have certifications on two different TechIDs. What should I do?

Your TechIDs will need to be manually updated. Send an email to certifications@apple.com with your exam
results and TechID information.

I passed my exam, but when I checked my certification it is not on certifications.apple.com. Why is my

certification missing?

Your certifications may take up to 72 hours to appear on certifications.apple.com after you pass the exam. If it
has been longer, please send an email to certifications@apple.com.

I have other questions. Where can I get them answered?

You can send your questions to svc.trng@apple.com.

Questions about Apple Certified iOS Technician (ACiT) 2018

What is ACiT 2018?

It's a program to become Apple-certified as an iOS technician.

How is ACiT 2018 different from previous ACiT 2017 certification?

ACiT 2018 qualifies a technician to repair iOS products that were produced before April 2018. This
includes:

iPhone 8 and iPhone 8 Plus

iPhone X
iPad (6th generation)

What exams are required for ACiT 2018?

To get ACiT 2018 certification, you need to pass the Apple Service Fundamentals Exam (SVC-18A) or
(SVC-17A) and the ACiT 2018 iOS Service Certification Exam (iOS-18A). These exams are available
from Pearson VUE. You can take the exams online from your own computer.

Does it matter in what order I take the exams?

Yes. Before you can register for the ACiT 2018 iOS Service Certification Exam (iOS-18A), you must
pass the Apple Service Fundamentals Exam.

How much does each exam cost?

 The cost of the exam is $20 USD (2,215 yen for Japan). Current pricing is available from Apple
Authorized Training Centers or Pearson VUE.

Where do I find the training for these exams?

Training for these exams is available in ATLAS. Access ACiT 2018 courses at Apple-authorized
service facilities.

I'm already ACiT 2017 certified. Do I need to take the new ACiT 2018 exams?

No. If you're certified for the iOS products you need to repair, no new exams are required.

Will separate iOS qualification exams be required for new iOS products?

No. Apple will introduce new qualification courses in ATLAS as products are introduced. You have to
complete these courses to service these new products.

I've completed the SVC-17A exam. How long will the iOS-17A exam be available? Do I need to
take two new exams for ACiT certification?

If you've completed the SVC-17A for ACiT 2017, the ACiT exam will be available until July 27, 2018.
Until then, completion of SVC-17A and iOS-17A exams will still grant you ACiT 2017 certification, but
it won't cover as many products. To get ACiT 2018 certification, the SVC-18A and iOS-18A exams are
required.

What will I have to do to service new iOS products that are introduced after I'm certified?

Apple will introduce new qualification courses in ATLAS as products are introduced. You have to
complete these courses to service these new products.

I have completed the Apple Certified Mac Technician (ACMT) 2018 certification. Do I need to
take two new exams for ACiT certification?

No. If you're ACMT 2018 certified, you've passed the Apple Service Fundamentals Exam. You only
need to pass the ACiT 2018 iOS Service Certification Exam (iOS-18A) to be ACiT 2018 certified.

When I complete the requirements for ACiT 2018, will I get a printed certificate?

Yes. After you pass the required exams, send an email to certifications@apple.com and ask for a
certificate. You'll get an email with a link to the request form.

I have other questions. Where can I get them answered?

You can send your questions to svc.trng@apple.com.

Questions about Apple Certified Mac Technician (ACMT) 2018

What is ACMT 2018?

Apple Mac Technician (ACMT) 2018 is a new version of the Apple Certified Mac Technician
certification.

How is ACMT 2018 different from previous ACMT certifications?

ACMT 2018 qualifies a technician to repair all the Mac products that were covered by prior ACMT
certifications, plus all other Mac products that were produced before April 2018. This includes
MacBook and MacBook Pro products that required a separate qualification exam or course in ATLAS:

MacBook (Retina, 12-inch, 2017)

MacBook Air (2017)
MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports)
MacBook Pro (13-inch, 2017, Two Thunderbolt 3 Ports)
MacBook Pro (15-inch, 2017)
iMac Pro (2017)
iMac (2017)

ACMT 2018 allows a technician who works at an Apple-authorized service facility to service all of
these products.

What exams are required for ACMT 2018?

To get ACMT 2018 certification, you need to pass the Apple Service Fundamentals Exam (SVC-18A)
or (SVC-17A) and ACMT 2018 Mac Service Certification Exam (MAC-18A). These exams are
available from Pearson VUE. You can take the exams online from your own computer.

Does it matter in what order I take the exams?

Yes. Before you can register for the ACMT 2018 Mac Service Certification Exam (MAC-18A), you
must pass the Apple Service Fundamentals Exam.

How much do each of the exams cost?

The cost of the exam is $20 USD (2,215 yen for Japan). Current pricing is available from Apple
Authorized Training Centers or Pearson VUE.

Where do I find the training for these exams?

Training for these exams is available in ATLAS. You can access ACMT 2018 courses at Apple
authorized service facilities.

I'm already ACMT 2017 certified. Do I need to take the new ACMT 2018 exams?

No. If you're certified for the Mac products you need to repair, no new exams are required.

I've completed the Apple Certified iOS Technician (ACiT 2018) certification. Do I need to take
two new exams for ACMT certification?

No. If you're ACiT 2018 certified, you've already passed the Apple Service Fundamentals Exam. You
only need to take and pass the ACMT 2018 Mac Service Certification Exam (MAC-18A) to be ACMT
2018 certified.

Will separate Mac qualification exams still be available?

Apple will publish new qualification courses in ATLAS for new Apple products as needed. If you're
already ACMT certified and want to repair a product with separate course requirements, you'll be able
to do so.

I've completed one of the previous ACMT 2017 exams. Do I need to take two new exams for
ACMT certification?

If you've completed the SVC-17A exam for ACMT, the remaining ACMT exam will be available until
July 27, 2018. Until then, completion of SVC-17A and MAC-17A exams will still grant you ACMT 2017
certification, but it won't cover as many products. To get ACMT 2018 certification, the SVC-18A / SVC-
17A and MAC-18A exams are required.

What will I have to do to service new Mac products that are introduced after I'm certified?

Apple will introduce new qualification courses in ATLAS as products are introduced. You have to
complete these courses to service the new products.

When I complete the requirements for ACMT 2018, will I get a printed certificate?

Yes. After you pass the required exams, send an email to certifications@apple.com and ask for a
certificate. You'll get an email with a link to the request form.

I have other questions. Where can I get them answered?

You can send your questions to svc.trng@apple.com.

Required Tools

Required Tools for iMac (Late 2012 – 2017) and iMac Pro (2017) Models

The following tools are required to service these models:

iMac Pro (2017)

iMac (Retina 5K, 27-inch, Late 2014, Mid 2015, Late 2015, 2017)
iMac (27-inch, Late 2012 and Late 2013)
iMac (Retina 4K, 21.5-inch, Late 2015 and 2017)
iMac (21.5-inch, Late 2012, Early 2013, Late 2013, Mid 2014, Late 2015, 2017)

For more information about tools, refer to article OP101: Apple notebooks and desktops: Hand Tools for Repairs.

General Tools

ESD-safe workstation, including an ESD mat and wrist or heel strap

ESD bags, to store ESD-sensitive parts while removed from the computer
ESD-safe tweezers.
Black stick or other nonconductive nylon or plastic flat-bladed tool
Black stick, pack of 4 (922-5065)
Black stick, pack of 24 (922-9004)
Black stick, pack of 96 (922-9005)
Digital volt meter, for troubleshooting
Earphones, for audio cable reassembly
Kapton tape
Magnifying glass, for reading the serial number
Pentalobe driver (923-0367), for VESA mount
Phillips #00 screwdriver
Sticky notes
Thunderbolt and USB cables, for logic board replacement
Torx T4 screwdriver (magnetized)
Torx T5 screwdriver (magnetized)
Torx T6 screwdriver (magnetized)
Torx T8 screwdriver (magnetized)
Torx T10 screwdriver (magnetized)
Torx T25 screwdriver (magnetized), for 27-inch models
Adjustable torque driver 0.3–1.2 Nm (923-0735)
T8 security bit (923-0734)
Logic Board Service Tray (076-00376)

Display Tools

The display is secured to the rear enclosure using adhesive strips. When a repair requires the removal of the display panel,
the very high bond (VHB) adhesive strips must be cut and replaced.

Display starter kit and refill kits

Model Starter kit Refill kit
iMac (21.5-inch, Late 2012) 076-1444 076-1437
iMac (21.5-inch, Early 2013) 076-1444 076-1437
iMac (21.5-inch, Late 2013) 076-1444 076-1437
iMac (21.5-inch, Mid 2014) 076-1444 076-1437
iMac (21.5-inch, Late 2015) 076-1444 076-1437
iMac (21.5-inch, 2017) 076-00330 076-00331
iMac (Retina 4K, 21.5-inch, Late 2015) 076-1444 076-1437
iMac (Retina 4K, 21.5-inch, 2017) 076-00330 076-00331
iMac (27-inch, Late 2012) 076-1444 076-1419
iMac (27-inch, Late 2013) 076-1444 076-1419
iMac (Retina 5K, 27-inch, Late 2014) 076-1444 076-00009
iMac (Retina 5K, 27-inch, Mid 2015) 076-1444 076-00009
iMac (Retina 5K, 27-inch, Late 2015) 076-1444 076-00009
iMac (Retina 5K, 27-inch, 2017) 076-00330 076-00332
iMac Pro (2017) 076-00374 076-00375

Display starter kit contains:

Display removal tool (1) (the white handle shown here), also available separately as 076-00108
Display removal wheels (8) (the black circle on the left side of tool shown here)

iMac service foam locking wedge (not available separately)

Note: The number on the side of the foam wedge (944-4365) is an Apple internal part number used for identification. It
is not an orderable service part.

VHB adhesive strip 6-piece set for iMac Pro (2017)

VHB adhesive strip 6-piece set for iMac (27-inch, 2017) (4 sets)
 VHB adhesive strip 6-piece set for iMac (21.5-inch, 2017) (4 sets)

VHB adhesive strip 6-piece set for iMac (21.5-inch, Late 2012–Mid 2015 models)

Display refill kits contain:

Display removal tool (1), also available separately as 076-00108

Display removal wheels (20), also available separately as 076-1417
VHB adhesive strip 6-piece set (20 sets)

Other display tools:

Display cable extension kit, to test the display panel and cables with the display panel removed
076-1428 for iMac (21.5-inch, Late 2012–2017 models)
076-00200 for iMac (Retina 4K and 2.8 GHz, 21.5-inch, Late 2015)
076-1431 for iMac (27-inch, Late 2012 and Late 2013)
076-00010 for iMac (Retina 5K, 27-inch, Late 2014, Mid 2015, Late 2015, 2017) models, iMac (Retina 4K, 21.5-
inch, 2017), and iMac Pro (2017)
Display removal tool (076-00108)
Display removal wheels, pack of 20 (076-1417)
ESD bags, 27x18-inch, pack of 5 (923-01193), for a 27-inch display
ESD bags, 21x16-inch, pack of 5 (923-01194), for a 21.5-inch display
Isopropyl alcohol (IPA) wipes, 95% or higher isopropyl
LCD service support stand (923-0416), to support the LCD panel or when working on a VESA mount-adapted system
 Painter’s tape (tape that does not leave a residue, 1 to 2 inches wide, but preferably 2-inch, if available)
Polishing cloths, anti-static, optical-grade microterry, pack of 5 (922-8263)
Power supply protective covers (923-0189), to use when performing live adjustments with the display panel removed
Sticky silicone roller (6-inch) (922-8261), to adhere VHB strips to the display panel
Sticky sheet pads (922-8262), to clean silicone roller or pick up shards of broken glass

Wireless Card Tools

Thermal pad kit (076-1445)

Note: Whenever removing or replacing the wireless card, check for any original thermal material. If it is present, then
remove the original thermal material, clean the area with an IPA wipe, and install one thermal pad to the wireless card.
Antenna removal tool (optional)
923-01322

Wireless card support tools

923-02218 for iMac Pro (2017)

923-01806 for iMac (21.5-inch, 2017) and iMac (Retina 4K, 21.5-inch, 2017)

923-01807 for iMac (Retina 5K, 27-inch, 2017)

923-00774 for iMac (21.5-inch, Late 2015) and iMac (Retina 4K, 21.5-inch, Late 2015)

923-00775 for iMac (Retina 5K, 27-inch, Late 2015)

Power Supply Cover Instructions

WARNING: HIGH VOLTAGE: The power supply remains powered up whenever the computer is plugged in, whether
or not the computer has been turned on. Use extreme caution when troubleshooting with the display panel
removed. Avoid touching the logic board or power supply while the computer is plugged in.

Never remove or install any physical components while the computer is plugged in to an electrical outlet.
When plugged in, the power supply and logic board are energized, even when the computer is powered off.
Unplug computer and allow sufficient time for the power supply and logic board to self-discharge before removing
display panel.
Do NOT touch the logic board or power supply while the computer is plugged in, or before sufficient time has passed to
discharge stored voltage to a safe level after being unplugged.

Discharge wait time:

Wait two minutes after unplugging the computer from the electrical outlet before removing display panel, disconnecting
modules, or substituting cables and components. This will allow the power supply and logic board time to discharge.

Electrical Safety Precautions:

Before working on a computer with exposed, potentially energized parts:

Remove rings, watches, necklaces, metal-rimmed eyewear, and other metallic articles which increase your risk of
electric shock.
Do not wear a cell phone or other signaling device, as these may cause a dangerous startle reflex during energized
work.
If the iMac needs to be plugged in for LED checks or similar troubleshooting, do NOT wear an ESD wrist strap.
Wearing ESD grounding systems increases your risk of electric shock.
Remain alert, focused on the work being performed, and aware of the proximity of grounded objects to your body.
Use the plastic black stick or other non-metal extension tool as needed to connect or disconnect cables, to keep fingers
away from potentially energized parts.

Tools Required

A ruler
Kapton tape or painter’s tape
Power supply protective cover, 923-0189, pkg. of 2

1. Before using the power supply cover for the first time, position the cover with the part number face-down, then fold the
cover once to create a 90-degree bend. The fold location is marked by a linear indentation (see dotted line in image) in
the cover. Use a ruler as a guide to make the fold.
 2. The pre-formed bends allow the cover to fit the rear housing on a variety of iMacs and displays (as shown).
3. Secure the power supply cover with Kapton or painter’s tape as shown below.

Warning: Place a cover over the power supply when doing live adjustments. Avoid touching the power supply while the
computer is plugged in.

4. The power supply protective cover may be reused. However, before reusing, visually inspect for:

Holes, tears, punctures, or cuts.

Textural defects such as swelling, softening, hardening, or stickiness.
 Other defects that degrade insulating quality.

5. If any wear or other defects are found, discard and use a new cover (923-0189).
Safety

Safety for iMac Pro (2017)

Warning: HIGH VOLTAGE. Use extreme caution when troubleshooting with the display panel removed. Avoid
touching the logic board or power supply while the computer is plugged in, the power supply retains a charge
whether or not the computer is on.

After unplugging the computer from the electrical outlet, wait two minutes before removing the display panel,
disconnecting modules, or substituting cables and components. This will allow the power supply and logic board
time to discharge.

Never remove or install any physical components while the computer is plugged in to an electrical outlet.
When plugged in, the power supply and logic board are energized, even when the computer is turned off.
Unplug the computer and allow sufficient time for the power supply and logic board to self-discharge before removing
the display panel.
Do NOT touch the logic board or power supply while the computer is plugged in, or before sufficient time has passed to
discharge stored voltage to a safe level after being unplugged.

Refer to article TP1620: iMac Pro (2017): Power Supply Cover Instructions for additional information on installing the
protective covers. The power supply cover provides protection against unintended contact with the energized power supply,
which may result in injury from electric shock. ALWAYS use the protective power supply cover during service when the glass
panel and LCD have been removed from the iMac Pro (2017).

Electrical Safety Precautions

Before working on a computer with exposed, potentially energized parts:

Remove rings, watches, necklaces, metal-rimmed eyewear, and other metallic articles which increase your risk of
electric shock.
Do not wear a cell phone or other signaling device, as these may cause a dangerous startle reflex during energized
work.
If the iMac needs to be plugged in for LED checks or similar troubleshooting, do NOT wear an ESD wrist strap.
Wearing an ESD grounding system increases your risk of electric shock in this situation.
Remain alert, focused on the work being performed, and aware of the proximity of grounded objects to your body.
Use the plastic black stick or other non-metal extension tool as needed to connect or disconnect cables, to keep fingers
away from potentially energized parts.

Power Supply Location

Logic Board Location
Protective Power Supply Cover Placement

Warning: Use the protective power supply covers when the computer is plugged in or when performing live adjustments. On
these models, place a cover over both the power supply and the logic board when doing live adjustments. Secure the covers
to the rear housing with tape, as shown below. Avoid touching the logic board or power supply while the computer is plugged
in and the display panel is removed.

Refer to articles:

TP1620: Power Supply Cover Instructions

TP981: Testing the Panel Using the Display Extension Cable Kit
Cleaning and Handling a Broken Display Panel

Cleaning and Handling a Broken Display Panel for iMac (Late 2012–2017) and iMac Pro (2017)

Tools for Cleaning the Display Panel

Safety glasses
Service wedge (iMac) (included with the display panel starter kit, 076-1444)
Clean, damp cloth (to clean display panel glass)
Isopropyl alcohol (IPA) wipes (to remove residual VHB adhesive)

Cleaning the Display Panel

1. Clean the front of the display with a clean, damp, lint-free cloth. Note: Do not use IPA wipes to clean the display. IPA
wipes should only be used to remove residual VHB adhesive.
2. Polish the display panel with an antistatic, microterry, optical-grade polishing cloth (922-8263, package of five).

Glass Safety Precautions

All models have a glass display panel that attaches to the front of the computer, which must be removed to access internal
components.

Handling a Broken Display Panel

The display panel’s glass is not tempered and will break into sharp pieces if mishandled. Removing the display panel
requires special tools.
Safety glasses are recommended when removing the display panel.

Tools

Display panel starter kit (Refer to TP818: Required Tools for part numbers.)
Material handling gloves (such as leather or cut-resistant gloves)
Packing tape or equivalent
Safety glasses
 Large ESD bags (922-8258) – 24x20-inch bags that accommodate a 21.5-inch display, package of five
Large ESD bags (922-9468) – 24x30-inch bags that accommodate a 27-inch display, package of five
Large box for disposal

Safety Information

If the display panel breaks and a glass shard enters the eye:

Seek medical attention immediately!

Do not rub your eye if you feel you have something in your eye.
Do not use an eye wash. An eye wash can push or move the shard of glass and cause more damage.
Keep the eye closed or loosely patch the eye to keep the eye from moving.

Handling a Broken Display Panel

1. Put on safety glasses and material handling gloves.

2. If the display panel is broken and is still attached to the rear housing, then secure the broken glass with packing tape
and carefully follow the Display Panel Removal procedure.
RP1021: iMac (21.5-inch, Late 2012, Early 2013, Late 2013, Mid 2014): Display Panel Removal
RP1230: iMac (21.5-inch, Late 2015 and 2017) and iMac (Retina 4K, 21.5-inch, Late 2015 and 2017): Display
Panel Removal
RP950: iMac (27-inch) Display Panel Removal
RP1403: iMac Pro (2017) Display Panel Removal
3. Lay the display panel on a smooth, clean work surface.
4. Apply tape, thoroughly covering the broken display panel.
4.

5. Place the taped display panel in the ESD bag that the replacement panel came in (or an equivalent large bag).

6. Place the display panel inside a large box, label the box “Broken Glass,” and return the display back to Apple using
the normal return process.
Take Apart Procedure Notes

Reassembly Steps

When no replacement steps are listed, replace parts in exact reverse order of Removal procedure.

Note About Images in This Guide

In some cases a pre-production model may have been used to document the procedures in this guide. Although there may
be small differences in appearance between the image pictured and the computer you are servicing, the procedures are the
same unless noted.

Screw Sizes

All screw sizes shown are approximate and represent the total length of the screw.
Display Panel Removal
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV364: Display Panel Replacement Video.

Before you begin:

Shut down the computer.

Unplug power and disconnect peripherals.
Put on an ESD wrist strap.

Tools

ESD wrist strap

Service wedge (iMac)
ESD-safe bag (not pictured)
Black stick
Display removal tool
Replacement wheels for display removal tool (several)
Safety glasses
The display panel must be removed for all repairs. The display is affixed to the computer housing with very high bond (VHB)
adhesive strips. These VHB strips must be cut with the display removal tool in order to remove the LCD panel. Each VHB
strip consists of two adhesive layers and a foam layer (VHB/foam/VHB). When you remove the display, you are cutting
primarily through the foam layer.

The main tool is the display removal tool. The tool uses replaceable wheels (076-1417) that cut through the foam layer in the
VHB strip. With careful use, these wheels can be reused five to ten times. When the wheel becomes nicked from contact
with the chin, further use becomes difficult. Because of this, the tool should only be used along the top and sides of the
display, and not along the chin. To remove the VHB strips along the chin, lower the display and pull the outer vertical tab on
the strips.

Steps For Removal

Important: In the unlikely event that the display glass cracks or breaks, refer to TP819: Cleaning and Handling a Broken
Display Panel.

1. Use the service wedge to hold the display steady. When positioned correctly, the service wedge covers the power
receptacle. Rotate the computer so the display panel is facing you.

2. Place a wheel on the removal tool by inserting the wheel into the notch on the handle. Push firmly until the wheel clicks
into the notch. The tool cuts the foam core, which is located between two layers of VHB adhesive that secure the display
panel to the rear housing.
Caution: If the wheel becomes worn during use, then change the wheel. A worn wheel could permanently damage the black
Mylar that is adhered to the edges on the back of the display panel glass.

3. Use only the display removal tool to cut through the foam layer of the VHB adhesive. Insert the display removal tool into
the gap between the display panel and rear housing. Hold the display removal tool perpendicular to the edge of the
computer.

Note: The tool should only be used along the top and sides of the display, not along the chin.

4. Avoid the top center edge of the display where the delicate microphone flex cables and camera are located. Allow a 3-inch
(7.62-cm) protective zone here.
5. Roll the tool along the sides of the display panel. Move the tool back and forth until it moves with minimal resistance.
6. Pay special attention to the top corners, as the tool must make steady contact with the display and housing.

7. Use the flat end of a black stick to gently remove any visible VHB from the edges of the rear housing.

Caution: Forcing the black stick between the display panel and the rear housing may cause the display panel to fracture.
Caution: Pay special attention to the location of the Wi-Fi/Bluetooth antennas. Do not pry in these areas with the black
stick.
8. Use the black stick and your fingers to carefully separate the display panel from the top of the rear housing. If there is
resistance, then you need to remove more VHB material.

9. Tilt the display open slightly, just enough for your hand to reach the cables that connect the display to the logic board.

Caution: Be extremely careful not to stress the display cables and connectors on the logic board when tilting the display
open. The display connectors on the logic board are easily damaged. If the connectors are damaged, then the logic board
will need to be replaced.

Remember that the bottom edge of the display is still attached with VHB. Do not remove the display panel yet.
10. Carefully remove the Embedded DisplayPort (eDP) cable (2) from the logic board by moving the locking lever up and
pulling the cable straight out of its connector. Disconnect the display backlight power cable (1) from the logic board by
pinching the sides and pulling the power cable straight out of its connector.

Note: The display backlight power cable is part of the display panel assembly and is not a separate part.
11. Disconnect the camera cable from the logic board by lifting the locking lever and pulling the cable straight out of its
connector.

12. Lower the display panel. Locate the two VHB strips along the chin. Pull the VHB tab on each strip toward the center.
13. Gently pull the display panel off of the rear housing and store it in an ESD-safe bag.

Caution: If the panel is sticking to the rear housing, then use a black stick to carefully break the VHB bond between the
display and rear housing. Be careful not to damage the black Mylar on the display. If the black protective Mylar is pulled from
the display, then the display panel may need to be replaced.
Steps For Reassembly
1. Remove the display panel VHB strips.

2. Install new display panel VHB strips.

3. Reinstall the display panel.

Display Panel - Removing Very High Bond (VHB) Strips
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel

Note: These images are representative. It is possible for residual VHB to be located anywhere along the edges of the display
and the enclosure.
Tools

ESD wrist strap and mat

Service wedge (iMac)
Black stick
Isopropyl alcohol (IPA) wipes

Steps For Removal

Note: On the rare occasion that the display glass cracks or breaks, refer to article TP819: Cleaning and Handling a Broken
Display Panel.

1. Use your fingers and the flat end of a black stick to remove any residual very high bond (VHB) adhesive that is left on the
rear housing.
2. Peel the VHB from the display panel.

Note: Be careful when removing VHB from the display panel. To prevent damage to the black Mylar protective film that is
located on the display panel glass, ensure you are peeling up the VHB and not the Mylar film. An easy way to ensure that
you do not peel up the Mylar film on the display is to start peeling the VHB from the center points, not from the corners of the
display.

Top of display shown. Peel VHB to the left and right, above the camera module location.
At the bottom corners of the display, peel the VHB upward.
Note: If the black protective Mylar film is peeled or wrinkled on the display, then press the film back onto the panel with your
finger. The Mylar should be smooth and undamaged. Use caution when working around the black Mylar protective film. If the
Mylar is pulled from the display, then the display panel may need to be replaced.

3. Do not peel VHB from the display corners. The chance of damaging the black Mylar protective film is greater if VHB
removal is started in the corner.

4. Remove any remaining adhesive by wiping the rear housing and display panel edges clean with an IPA wipe. Continue
until the surfaces no longer show VHB residue.
Caution: Do not use IPA wipes on the display. IPA wipes should only be used to remove residual VHB adhesive. Be careful
not to get IPA wipes on the display while removing the VHB residue.

5. Allow the surfaces to dry for one minute.

6. Check again to ensure the display and rear housing are clean of VHB.

Steps For Reassembly

1. Install new display panel VHB strips.

2. Reinstall the display panel.

Display Panel - Replacing Very High Bond (VHB) Strips
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips

Tools
ESD wrist strap and mat
Service wedge (iMac)
Black stick
Display Refill Kit, VHB strips, 6-piece set, 20-pack (076-00375)

Steps For Removal

This is a reassembly instruction article. For removal steps, see article RP1404: Display Panel - Removing Very High Bond
(VHB) Strips.

Steps For Reassembly

1. Each VHB strip has an ID number on the pull tab and part number (946-xxxx) printed on the strip. Use the table and
pictures below to verify that you have all of the needed VHB strips. Lay out the VHB strips before installing them onto the
computer and check them for damage. Check that there are no wrinkles or exposed sections on the strip. Damage can
cause cosmetic gap issues, make the display bond weak, or create light leakage.

VHB Strip VHB Strip ID Part Number on VHB

Description Number Strip
Top left 33 946-0943
Top right 32 946-0942
Right side 21 946-03774
Bottom right 14 946-4551
Bottom left 15 946-4550
Left side 16 946-4552

2. The VHB strips have a foam layer (VHB/foam/VHB), with a removable liner on the underside and a clear plastic liner on
the top side. Use the plastic pull tab to peel the paper liner from the underside of the VHB strip.

Note: The color of the removable liner may vary between VHB vendors.
3. The rear housing has eight alignment holes. Use them to align the new VHB strips.

Important: Before adhering the VHB strips and installing the display, verify that all cables are connected, all screws are
installed, and that there is no debris present in the computer.
4. Peel the paper off of the back of the VHB strips.

5. Use the pointed end of a black stick to align the VHB strips on the rear housing. Note: The paper liner side faces the rear
housing.

6. As you position the VHB, use your finger to peel the remaining paper liner from the underside of the VHB strip.

7. Use your finger to press the VHB strip into place on the rear housing. Note: If a VHB strip does not line up correctly,
remove it and start again.

8. Do not remove the clear plastic liners from the top layer of the strip at this time. Remove them right before you replace the
panel.
9. Repeat the VHB process (align, peel paper liners, press VHB into place) along the top edge of the rear housing. Press
with your fingers to adhere the strips to the rear housing.

10. Two strips of VHB are used along the bottom edge. There are no guide holes on the VHB strip or rear housing for the
bottom strips. Align the strips carefully by hand.
11. Note: If any VHB strip does not line up correctly, then remove it, clean the rear housing, and start again. Check that there
are no wrinkles or exposed sections on the strip. Damage can cause cosmetic gap issues and may make the display bond
weaker or create light leakage.

12. To install the display panel, refer to RP1406: Display Panel Reassembly.
Display Panel Reassembly
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV364: Display Panel Replacement Video.

Replace:

Display Panel VHB Strips

Tools

Service wedge (iMac)

Isopropyl alcohol (IPA) wipes (to remove residual VHB adhesive)
Safety glasses
Painter’s tape (tape that does not leave a residue, 1 to 2 inches wide, preferably 2 inches, if available)
Silicone display roller
Clean, damp, lint-free cloth (to clean display panel glass)

Steps For Removal

This is a reassembly instruction article. Before you begin, refer to the following articles:
 RP1403: Display Panel Removal
RP1404: Display Panel - Removing Very High Bond (VHB) Strips
RP1406: Display Panel - Replacing Very High Bond (VHB) Strips

If you have already performed the removal and replacement tasks listed above, then proceed to the next step.

Steps For Reassembly

Important: In the unlikely event that the display glass cracks or breaks, refer to article TP819: Cleaning and Handling a
Broken Display Panel.

1. Insert the service wedge to hold the display steady for this procedure. When positioned correctly, the wedge covers the
power receptacle.

2. Before installing, ensure that any residual VHB is removed from the display panel and rear housing.

3. Place the display panel on the chin of the rear housing. Align the panel and check that it is centered and seated.
4. Use the display removal tool to check the alignment on both sides of the display. Adjust if necessary.
5. Anchor the display with a strip of painter’s tape. Place it over the bottom of the display and the edge of the rear housing.

6. Stand back to check the alignment of the display panel. If the rear housing can be seen, then adjust the panel and check
again.
Incorrect alignment

Correct alignment

7. Anchor the display further with more strips of painter’s tape. Place one or two vertical pieces along the edge for added
support.
8. Use one hand to tilt the display while steadying it with the other hand.
9. While continuing to steady the display with one hand, use the other hand to pull the clear release liners on the bottom VHB
strips. Pull the release liners carefully so they do not tear or break.
10. Remove the remaining release liners from the top and sides of the display panel.
11. Tilt the display up, leaving enough room to connect the Embedded DisplayPort (eDP) (2) and display backlight power (1)
cables to the logic board. If the eDP cable is not connected properly, it could result in no video or no power. If the camera
cable is not connected properly, it could result in the no camera or the camera not working properly. Check that the
connectors are firmly seated.

Important: Be extremely careful not to stress the display cables and connectors on the logic board when tilting the display
open. The display connectors on the logic board are easily damaged. If the connectors are damaged, then the logic board
will need to be replaced.
Note: The display backlight power cable is part of the display panel assembly and is not a separate part.

12. Connect the camera cable to the logic board.

13. After all the release liners have been removed, lower the display panel against the rear housing.

14. Use the silicone display roller to adhere the VHB strips to the glass. To prevent image quality issues the roller should
only apply pressure while moving from the bottom to the top. Do not repeatedly roll up and down.

Repeat the rolling along the top and the other side.

15. Clean the front of the display with a clean, damp, lint-free cloth.

Note: Do not use IPA wipes to clean the display. IPA wipes should only be used to remove residual VHB adhesive.
Embedded DisplayPort (eDP) Cable
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips

Tools

ESD wrist strap

Black stick

Steps For Removal

1. Remove any tape that secures the Embedded DisplayPort (eDP) cable to the display panel.
2. Use a black stick or a finger to “unlock” the lock bar by gently flipping the bar toward the eDP cable.

3. Gently pull the eDP cable out of the connector.

Steps For Reassembly

1. Remove the pull tab on the back of the cable to expose the adhesive before inserting the cable into the display panel
connector.

2. Insert the eDP cable into its connector. Flip the lock bar up, ensuring that the cable is securely connected.

Important: Press down around the lock bar to lock the lever into place.
Note: Press on the area of the cable with the adhesive, to secure the cable to the display panel.

3. Install new display panel VHB strips.

4. Reinstall the display panel.

Rear Mic Cable
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly

Tools

ESD wrist strap

Service wedge (iMac)
Black stick
Steps For Removal
1. With fingers or a black stick, disconnect one end of the flex cable from the logic board.

2. With fingers or a black stick, disconnect the other end from the enclosure.

3. With a black stick, gently loosen the adhesive to peel the cable from the enclosure.
Steps For Reassembly

1. Reconnect one end of the cable to the logic board.

2. With a black stick, gently press the cable down into the enclosure to reattach adhesive.

3. Reconnect the cable to the enclosure.

4. Reinstall the dual fan assembly.

5. Install new display panel VHB strips.

6. Reinstall the display panel.

Camera Cable
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips

Tools

ESD wrist strap

Service wedge (iMac)
Black stick

Steps For Removal

1. Use a black stick to flip up the lock bar toward the cable.
2. Gently pull the cable, not the lock bar, to disconnect the cable.

Steps For Reassembly

1. Reconnect the camera cable. Flip the lock bar up and check that it is secure.

2. Install new display panel VHB strips.

3. Reinstall the display panel.

Dual Fan Assembly
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV365: Dual Fan Assembly Replacement Video.

Remove:

Display Panel
Display Panel VHB Strips

Tools
ESD wrist strap
Torx T10 screwdriver (magnetized)
Black stick
Service wedge (iMac)

Steps For Removal

1. Gently lift the Mylar tabs from the right and left fan cables where they connect to the logic board.
2. With a black stick, flip open the locking lever and holding the flex cable, not the tabs, disconnect both flex cables.

3. Starting with the bottom screws, loosen the four T10 screws from the dual fan assembly.

T10: 923-00669
4. Using two hands, tilt the dual fan assembly and lift it out.

Steps For Reassembly

Note: If the standoffs came off of the enclosure when the dual fan assembly was removed, then refer to article SV365: Dual
Fan Assembly Replacement Video for instructions on reinstalling the standoffs.

1. Seat the dual fan assembly in the housing.

2. Tighten the four T10 screws.

 T10: 923-00669

3. Reconnect the left and right fan flex cables to the logic board. Gently press the Mylar tabs down.

4. Install new display panel VHB strips.

5. Reinstall the display panel.

Chin Strap
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips

Tools
ESD wrist strap and mat
Phillips #00 screwdriver (magnetized)
ESD-safe tweezers (optional)
Black stick
Service wedge (iMac)
Steps For Removal

1. Remove nine Phillips #00 screws.

#00: 923-01905

2. Set the chin strap aside. Caution: Be careful not to bend the chin strap.

Steps For Reassembly

1. Insert the chin strap into the rear housing. Be sure the metal screw holes face the inside edge of the chin on the rear
housing. The foam edge on the chin strap should be facing up.

2. Use a black stick or tweezers to press the chin strap against the front frame, if needed.
3. Install the nine Phillips #00 screws.

#00: 923-01905

4. Install new display panel VHB strips.

5. Reinstall the display panel.

Right Speaker
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Chin Strap

Important: Speakers must be replaced in pairs. If you replace the right speaker, then you must also replace the left speaker.
For left speaker removal and reassembly instructions, refer to article RP1414: Left Speaker.

Tools

ESD wrist strap and mat

Torx T10 screwdriver (magnetized)
Black stick
Service wedge (iMac)

Steps For Removal

1. Use two fingers or a black stick to slide out and disconnect the speaker cable located at the top of MLB near the wireless
card connector.

2. Remove three identical T10 screws.

T10: 923-0333
3. Tilt the speaker slightly to the right. Notice the flex cable routes under the wireless card on the logic board. Lift the speaker
out of the enclosure.

Steps For Reassembly

1. Carefully insert the speaker all the way into the rear housing.

Note: Push firmly to ensure that the speaker sits down inside the rear housing as far as possible. If the speaker is not
positioned correctly in the rear housing, then it can cause display interference issues.

2. Route the flex cable under the wireless card on the logic board.

3. Connect the speaker cable to the logic board.

4. Install the three T10 speaker screws.

 T10: 923-0333

5. Reinstall the chin strap.

6. Install new display panel VHB strips.

7. Reinstall the display panel.

Left Speaker
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Chin Strap

Important: Speakers must be replaced in pairs. If you replace the left speaker, then you must also replace the right speaker.
For right speaker removal and reassembly instructions, refer to article RP1413: Right Speaker.

Tools
ESD wrist strap
Torx T10 screwdriver (magnetized)
Torx T8 screwdriver (magnetized)
Black stick
Service wedge (iMac)
Steps For Removal

1. Use a T8 screwdriver to remove the ground screw that secures the left speaker cable with an O-ring to the lower left
corner of the logic board.

T8: 923-0331

2. Disconnect the flex cable from the logic board.

3. Remove the three identical T10 screws.

T10: 923-0333
4. Tilt the speaker up and rock it gently to remove it from the pocket in the housing.

Steps For Reassembly

1. Carefully insert the speaker all the way into the rear housing.

Note: Push firmly to ensure that the speaker sits down inside the rear housing as far as possible. If the speaker is not
positioned correctly in the rear housing, then it can cause display interference issues.
2. Connect the speaker cable to the logic board.

3. Use a T8 screwdriver to reconnect the ground screw to the lower left corner of the logic board.

T8: 923-0331
5. Reinstall the three identical T10 screws.

T10: 923-0333
10. Reinstall the chin strap.

11. Install new display panel VHB strips.

12. Reinstall the display panel.

Antennas
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Note: There is a fourth antenna that is permanently attached to the rear housing. If this antenna is damaged, the rear
housing must be replaced.

Remove:

Display Panel
Display Panel VHB Strips
Chin Strap
Right Speaker

1. Upper Antenna
2. Middle Antenna
3. Lower Antenna

Tools

ESD wrist strap

Service wedge (iMac)
Wireless support tool (923-02218)
Torx T4 screwdriver (magnetized)
Torx T5 screwdriver (magnetized)
Antenna tool (923-01322)
Black stick
 ESD-safe tweezers (optional)

Steps For Removal

Note: The images shown here are of the Bluetooth antenna. The procedure is the same for all three antennas.

1. To protect the logic board, slide the wireless support tool into place behind the right corner of the logic board.

2. Secure the tool in place by sliding it to the right and making sure it lines up correctly.

Caution: Keep the support tool in position while removing or replacing screws and when disconnecting or reconnecting
antenna cables to avoid flexing the logic board.
3. Remove the two T5 screws holding the antenna clip in place and remove the antenna clip.

T5: 923-02294
4. Make note of the teeth on the antenna clip for reassembly.

5. Use the antenna tool to disconnect the antenna.

6. With a black stick, remove the tape that affixes the antenna to the enclosure.

7. Remove the two identical T4 screws from the antenna and gently remove the antenna from the enclosure.

T4: 923-0304
Steps For Reassembly

1. Install two T4 screws to secure the antenna body to the rear housing.

T4: 923-0304

2. Using a black stick, press the tape down to secure the antenna the rear housing.
3. To protect the logic board, slide the wireless support tool into place behind the right corner of the logic board.

4. Secure the tool in place by sliding it to the right and making sure it lines up correctly.

Caution: Keep the support tool in position while removing or replacing screws and when disconnecting or reconnecting
antenna cables to avoid flexing the logic board.
5. Use the antenna tool or ESD-safe tweezers to reconnect the antenna cable.
6. Reinstall the antenna clip by engaging the teeth at an angle and then lay it down over the antennae.

7. Reinstall the two T5 screws.

T5: 923-02294
8. Remove the wireless support tool from the rear housing.

9. Reinstall the right speaker.

10. Reinstall the chin strap.

11. Install new display panel VHB strips.

12. Reinstall the display panel.

Logic Board
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV366: Logic Board Replacement Video.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker

Tools

ESD wrist strap

ESD-safe tweezers
Black stick
Torx T4 screwdriver
Torx T5 screwdriver
Torx T8 screwdriver
Adjustable torque driver 0.3–1.2 N m (923-0735)
T8 security bit (923-0734)
Service wedge (iMac)
Wireless support tool (923-02218)
Antenna tool (923-01322)
Thunderbolt 3 cable or USB-C cable for reassembly
 Logic board service tray (076-00376)

Steps For Removal

Caution: The iMac Pro (2017) will not start up after a logic board and/or flash storage replacement until the Mac
Configuration Utility (MCU) is used. MCU is needed to serialize a logic board after a logic board replacement and to
configure the flash storage after new flash storage is installed. For instructions on how to use MCU, refer to article TP1625:
How to Use Mac Configuration Utility and service video SV369: System Configuration after a Logic Board or Flash Storage
Repair.

Note: In order to avoid flexing or causing damage to the logic board, always place the logic board in the logic board service
tray when it is removed from iMac Pro (2017). Before removing the logic board, prepare the tray. For instructions, refer to
article TP1635: Logic Board Service Tray Instruction.

Important: Before replacing the logic board, check the CPU warranty labels for signs of tampering. If all four CPU warranty
labels are intact, proceed with the repair. If the labels have been tampered with, the logic board should be replaced as an
out-of-warranty repair.

Intact labels:
 Tampered labels:

Procedure:

1. Carefully disconnect the following from the logic board:

1. Rear mic flex cable

2. Power button flex cable
3. Power supply flex cable
Caution: Be very careful with the power button flex cable. A broken cable requires a rear housing replacement. It is
recommended to tape the cable to the rear housing with Kapton tape to avoid damaging it.

2. Remove the T8 and T5 screws, then remove the cowling over the audio jack connector.

T8: 923-0331

T5: 923-02291
3. Disconnect the audio jack flex cable from the logic board.

4. To protect the logic board, slide the wireless support tool into place behind the right corner of the logic board.
5. This image shows the wireless support tool correctly installed. Keep the tool installed whenever removing the antenna clip
screws or wireless antennas.

6. Remove the two T5 screws on the antenna clip and remove the clip. Make note of the teeth on the antenna clip for
reassembly.

T5: 923-02294
7. Disconnect the wireless cables with the antenna tool.
8. Remove the support tool from the enclosure.

9. Remove the four T8 bus bar screws and discard them. Use new screws every time they are removed. New screws come
with a new logic board.

T8: 923-02288
10. Remove the four short T8 screws and two long T8 screws (top middle) from the logic board.

T8 short: 923-0331

T8 long: 923-0396
11. With two hands, gently grasp the logic board on the right and left side. Be careful not to flex the logic board while tilting it
forward slightly.

12. Tilt the board slightly to the right, then up and out, making sure to clear the SD card reader on the bottom right.

Caution:

Handling the logic board incorrectly can damage chips and circuits. Be extremely careful when removing and replacing
 the logic board. Components that contact the enclosure, standoffs, or other modules may cause damage and prevent
the iMac from operating correctly.
Always be careful not to flex the board.
Always handle the board by the edges. Do not handle the heat sink.

13. Place the logic board in the logic board service tray. For instructions, refer to article TP1635: Logic Board Service Tray
Instructions.

Steps For Reassembly

1. If you are installing a replacement logic board, transfer these parts from the old logic board:

Memory
Flash Storage

Note:

The logic board and the cards are marked to make sure each is reinstalled in the correct slot.
The flash storage devices are paired to the logic board and the data cannot be accessed or recovered when installed in
another logic board. Make sure the customer has a working backup of their data before removing or replacing the flash
storage devices.

2. Caution: When reassembling the logic board, be careful not to bend or damage the bus bars on the power supply. If the
bus bars are bent they must be replaced. Refer to article RP1419: Power Supply Bus Bars for instructions on how to replace
the bus bars.
3. With two hands, carefully place the logic board back into the enclosure, again being careful to clear the SD card port on
the lower right corner and not to flex the board.

4. To help with alignment, partially reinstall two T8 screws in the upper right corner of the logic board.

Note: A long T8 screw is used in the top middle and a short T8 screw in the top right.

5. Check that the bus bar teeth are visible through the oval holes in the logic board.
6. Replace the four silver T8 screws with new screws that come with the replacement logic board. Partially install the screws,
making sure the teeth are still visible through the holes.

T8: 923-02288
7. To further ensure correct logic board alignment with the rear housing, plug in a USB-C or Thunderbolt 3 cable into two
ports before tightening the logic board screws.

8. Once the alignment is secured, attach the Torx T8 security bit to the adjustable torque driver and tighten the silver T8 logic
board screws to 6.6 inch pounds (in.-lb.) or 0.75 Newton metres (N m).
9. Tighten the T8 screws in the upper right of the logic board and reinstall the rest of logic board screws.

Note: A long T8 screw is used in the top middle, the three other screws are short T8 screws.

10. Reconnect the microphone, audio, power button, and power supply flex cables to the logic board.

Caution: Be careful note to bend or damage the power button flex cable. Damage to this cable will require a rear housing
replacement.
11. Reinstall the cowling over the audio jack flex cable in the lower right corner. Secure the cowling by reinstalling the T8 and
T5 screws.

12. To protect the antennas, slide the wireless card support tool (923-02218) into place between the rear housing and the
wireless card. Reconnect the antennas to the wireless card using the antenna tool or ESD-safe tweezers.
13. Reinstall the antenna clip. Replace at an angle to engage the teeth, then lay flat and reinstall the two T5 screws.
14. Remove the support tool from the rear housing.

15. Reinstall the left speaker.

16. Reinstall the right speaker.

17. Reinstall the chin strap.

18. Reinstall the dual fan assembly.

19. Install new display panel VHB strips.

20. Reinstall the display panel.

Caution: If a replacement logic board has been installed, Mac Configuration Utility must be run. Refer to article TP1625:
How to use Mac Configuration Utility.
Logic Board Service Tray Instructions

The logic board service tray must be used for the following repair procedures:

Logic Board
Memory
Flash Storage
Battery

Note: The logic board service tray and stiffeners come in two separate kits:

076-00376 has the logic board service tray and storage box.
923-02217 has the single stiffener and the dual stiffener with six Phillips screws.

Both stiffeners are returned with a known-bad board (KBB). Replacement logic boards include replacement stiffeners.

Follow these steps to use the service tray:

1. Line up the single stiffener with the pins on the tray.

2. Place the single stiffener on the tray.

3. Place the logic board on the tray using the white blocks as a guide. Install the three Phillips head screws using an
adjustable torque driver set to 0.3 Nm and a PH2 bit. As pictured below, the short screw is installed on the left and the long
screws in the standoffs.
4. Slide the dual stiffener onto the logic board. Notice the board is sandwiched between the two halves of the dual stiffener.

5. Hold the block for leverage and tighten the middle screw first. Then tighten the right and left screws. Note: The screws act
as captive screws and are not meant to be removed from the dual stiffener.
6. Now that the logic board is secure, the memory, flash storage, or battery can be serviced.

7. After service is complete, remove the stiffeners and reinstall the logic board.

8. If a KBB is being returned, lift the board off of the tray with the stiffeners still intact and ship the KBB with the stiffeners on.
Replacement logic boards include replacement stiffeners.
Flash Storage
First Steps

Caution: The flash storage devices are paired to the logic board and the data cannot be accessed or recovered when
installed in another logic board. Make sure the customer has a working backup of their data before removing or replacing the
flash storage devices.

Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV367: Flash Storage and Memory Replacement Video.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board

Tools

ESD wrist strap and mat

T8 security bit
Adjustable torque driver 0.3–1.2 N m (923-0735)
Steps For Removal

Caution:

The flash storage devices are paired to the logic board and the data cannot be accessed or recovered when installed in
another logic board. Make sure the customer has a working backup of their data before removing or replacing the flash
storage devices.
The iMac Pro (2017) will not start up after a logic board and/or flash storage replacement until the Mac Configuration
Utility (MCU) is used. MCU is needed to serialize a logic board after a logic board replacement and to configure the
flash storage after new flash storage is installed. For instructions on how to use MCU, refer to article TP1625: How to
Use Mac Configuration Utility and service video SV369: System Configuration after a Logic Board or Flash Storage
Repair.

Note: To perform this repair, the logic board must be in the logic board service tray. Refer to TP1635: Logic Board Service
Tray Instructions.

1. Remove one T8 screw from each flash storage card.

T8: 923-02313

2. Gently pull the flash storage straight out of the connector.

Caution: Do not lift the flash storage at an angle when removing it from the connector. Damage to the connector requires a
logic board replacement.
Steps For Reassembly

1. Insert the flash storage straight into the logic board connector.

Note: The flash storage must be reinstalled into the same connector it was taken out of. The flash storage is marked with
OO and O1. It is important to remember which slot each card was originally in.
2. Install one T8 screw to each flash storage card. Use the adjustable torque driver to tighten each screw to 2.65 inch pounds
(in.-lb.) or 0.3 Newton metres (N m).

T8: 923-02313

3. Reinstall the logic board.

4. Reinstall the left speaker.

5. Reinstall the right speaker.

6. Reinstall the dual fan assembly.

7. Reinstall the chin strap.

8. Install new display panel VHB strips.

9. Reinstall the display panel.

10. Refer to article TP767: Reinstalling Software That Came with the Computer.

Caution: If replacement flash storage has been installed, Mac Configuration Utility must be run. Refer to article TP1625:
How to use Mac Configuration Utility.
Reinstalling Software That Came with the Computer

Reinstalling Software That Came with the Computer

This procedure requires an Internet connection.

Note: In some situations, a user may have set a firmware password. The user must know the firmware password in order to
reinstall OS X or macOS. If the user cannot remember the password, then refer to the technician instructions in article
HT204455: How to set a firmware password on your Mac.

Important: Apple recommends that users back up their data before any software restore procedure. Back up essential files
before installing OS X or macOS. Apple is not responsible for any loss of data. For instructions on using Time Machine, refer
to article HT201250: How to use Time Machine to back up or restore your Mac.

For instructions on reinstalling the OS, follow the steps in article HT204904: How to reinstall macOS.

For more information about recovery mode, refer to article HT201314: About macOS Recovery.
Memory
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV367: Flash Storage and Memory Replacement Video.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board

Tools

ESD wrist strap

Service wedge (iMac)

Steps For Removal

Note: To perform this repair, the logic board must be in the logic board service tray. Refer to TP1635: Logic Board Service
Tray Instructions.
1. Locate the two levers on the right and left side of the memory slot. Push the levers outward to release the memory.

2. Hold the DIMMs by the sides and gently pull straight out in the direction the DIMMs are positioned in the slot. Be careful
not to bend the DIMM.

Steps For Reassembly

Note: If you are replacing DIMMS in slots 2 and 4, reinstall a new EMI absorber.
 Remove the protective backing from the new absorber.
Align one end of the absorber with the notched side of the replacement DIMM. Note: Make sure the absorber does not
cover the gold pins or the notch.
Press the absorber onto the DIMM so it is smooth.

Note: One absorber is included with each replacement DIMM service part. However, third-party DIMMs in slot 2 or 4 also
require the absorber. Use part number 923-02311 to order additional absorbers.

1. Make sure the levers on the memory slots are open.

2. Insert the DIMM into the slot. Use both thumbs to press the DIMM into place until both levers latch.

3. Check the slots and make sure the DIMM is fully seated.

4. Reinstall the logic board.

5. Reinstall the left speaker.

6. Reinstall the right speaker.

7. Reinstall the dual fan assembly.

8. Reinstall the chin strap.

9. Install new display panel VHB strips.

10. Reinstall the display panel.

Battery
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board

Tools
ESD wrist strap
Service wedge (iMac)
Black stick

Steps For Removal

Note: To perform this repair, the logic board must be in the logic board service tray. Refer to TP1635: Logic Board Service
Tray Instructions.

1. Remove the protective Mylar from the battery socket.

2. Use your finger to push the battery forward, to open a tiny gap between the battery and the battery socket. Insert the tip of
a black stick into the socket and carefully pry the battery out of the socket.
Steps For Reassembly

Warning: If the battery is installed incorrectly or replaced with an incorrect type of battery, there is a risk of explosion.
Dispose of used batteries according to local environmental laws and guidelines.

Note: Batteries for iMac Pro (2017) can not be ordered as a service part. If the battery needs to be replaced, the customer
can supply their own battery or the battery can be purchased from an outside supplier (BR2450A lithium coin cell battery).
When replacing the customer supplied battery, the Mylar must be ordered and replaced at the same time (923-02334).

1. Check that the battery socket on the logic board is open and free of dust.

2. Slide the battery into the socket with engraved markings (+ side) facing up.

3. Reinstall the logic board.

4. Reinstall the left speaker.

5. Reinstall the right speaker.

6. Reinstall the dual fan assembly.

7. Reinstall the chin strap.

8. Install new display panel VHB strips.

9. Reinstall the display panel.

Power Supply
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

For video instruction, refer to article SV368: Power Supply Replacement Video.

Remove:

Display Panel
Display Panel VHB Strips
Chin Strap
Dual Fan Assembly
Right Speaker
Left Speaker
Logic Board

Tools

ESD wrist strap

Service wedge (iMac)
Adjustable torque driver 0.3–1.2 Nm (923-0735) (for bus bar replacement)
T8 security bit (923-0734) (for bus bar replacement)
Torx T4 screwdriver (magnetized)
Torx T8 screwdriver (magnetized)
Steps For Removal

Warning: HIGH VOLTAGE. Use extreme caution when troubleshooting with the display panel removed. Avoid
touching the logic board or power supply while the computer is plugged in, the power supply retains a charge
whether or not the computer is on.

After unplugging the computer from the electrical outlet, wait two minutes before removing display panel,
disconnecting modules, or substituting cables and components. This will allow the power supply and logic board
time to discharge.

Never remove or install any physical components while the computer is plugged in to an electrical outlet.
When plugged in, the power supply and logic board are energized, even when the computer is turned off.
Unplug the computer and allow sufficient time for the power supply and logic board to self-discharge before removing
the display panel.
Do NOT touch the logic board or power supply while the computer is plugged in, or before sufficient time has passed to
discharge stored voltage to a safe level after being unplugged.

TP1620: iMac Pro (2017): Power Supply Cover Instructions

TP1637: iMac Pro (2017): Safety

Electrical Safety Precautions

Before working on a computer with exposed, potentially energized parts:

Remove rings, watches, necklaces, metal-rimmed eyewear, and other metallic articles which increase your risk of
electric shock.
Do not wear a cell phone or other signaling device, as these may cause a dangerous startle reflex during energized
work.
If the iMac needs to be plugged in for LED checks or similar troubleshooting, do NOT wear an ESD wrist strap.
Wearing ESD grounding systems increases your risk of electric shock.
Remain alert, focused on the work being performed, and aware of the proximity of grounded objects to your body.
Use the plastic black stick or other nonmetal extension tool as needed to connect or disconnect cables, to keep fingers
away from potentially energized parts.

1. Disconnect the AC power inlet cable by pressing the clip and pulling the cable away from the power inlet.
2. Remove the two identical T5 screws that secure the cable to the enclosure.

T5: 923-00609
3. Remove the four identical T8 screws in the order below.

T8: 923-02293
4. Lift the power supply out of the enclosure. Handle by the edges and be careful not to press on any of the components.

Steps For Reassembly

Caution: If the gasket on side of the power supply that faces the rear housing is missing, it must be replaced. Replacement
gaskets are included with a replacement power supply.
Note: The power supply replacement kit includes the following parts that will be labeled with the numbers below:

GPU bus bars (1) – 595-00140

CPU bus bars (2) – 595-00141
Bus bar to logic board screws – 452-00243
Bus bar to PSU screws – 452-2981
Gasket – 875-04789

For instructions on replacing the bus bars, refer to article RP1419: Power Supply Bus Bars.
1. Lower the power supply into the rear housing and reinstall two T5 screws that secure the cable to the enclosure.

T5: 923-00609
2. Reconnect the AC power inlet signal cable.

3. Align the corners of the power supply with the screw openings and reinstall the four T8 screws in the order shown.

T8: 923-02293
5. Reinstall the logic board.

6. Reinstall the left speaker.

7. Reinstall the right speaker.

8. Reinstall the dual fan assembly.

9. Reinstall the chin strap.

10. Reinstall the display panel VHB strips.

11. Reinstall the display panel.

12. Remove the bus bars from the KBB power supply before returning.
Power Supply Bus Bars
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Chin Strap
Dual Fan Assembly
Right Speaker
Left Speaker
Logic Board
Power Supply

Tools
ESD wrist strap
Service wedge (iMac)
Adjustable torque driver 0.3–1.2 N m (923-0735)
T8 security bit (923-0734)
Torx T8 screwdriver (magnetized)

Steps For Removal

Warning: HIGH VOLTAGE. Use extreme caution when troubleshooting with the display panel removed. Avoid
touching the logic board or power supply while the computer is plugged in, the power supply retains a charge
whether or not the computer is on.

After unplugging the computer from the electrical outlet, wait two minutes before removing display panel,
disconnecting modules, or substituting cables and components. This will allow the power supply and logic board
time to discharge.

Never remove or install any physical components while the computer is plugged in to an electrical outlet.
When plugged in, the power supply and logic board are energized, even when the computer is turned off.
Unplug the computer and allow sufficient time for the power supply and logic board to self-discharge before removing
the display panel.
Do NOT touch the logic board or power supply while the computer is plugged in, or before sufficient time has passed to
discharge stored voltage to a safe level after being unplugged.

TP1620: iMac Pro (2017): Power Supply Cover Instructions

TP1637: iMac Pro (2017): Safety

Electrical Safety Precautions

Before working on a computer with exposed, potentially energized parts:

Remove rings, watches, necklaces, metal-rimmed eyewear, and other metallic articles which increase your risk of
electric shock.
Do not wear a cell phone or other signaling device, as these may cause a dangerous startle reflex during energized
work.
If the iMac needs to be plugged in for LED checks or similar troubleshooting, do NOT wear an ESD wrist strap.
Wearing ESD grounding systems increases your risk of electric shock.
Remain alert, focused on the work being performed, and aware of the proximity of grounded objects to your body.
Use the plastic black stick or other nonmetal extension tool as needed to connect or disconnect cables, to keep fingers
away from potentially energized parts.

Note: The bus bars need to be replaced if bent or damaged in any way. New PSU will come with new bus bars, but bus bars
can also be ordered separately in the case of damage (923-02288).

1. Remove the four idential T8 screws from the bus bars.

T8: (923-0712)

CPU bus bars:

 GPU bus bars

2. Remove the bus bars and make note of how the bus bars are attached to the power supply before you remove them. They
must be replaced in the same way.

Steps For Reassembly

1. Replace the bus bars in the same direction they were taken off.
Caution: If the bus bars are facing the wrong way, damage to the power supply and/or the logic board can occur.

2. Reinstall the four idential T8 screws from the bus bars.

T8: (923-0712)

CPU bus bars

GPU bus bars

3. Using the adjustable torque driver and the T8 security bit, tighten the screws to 7.5 inch pounds (in.-lb.) or 0.85 Newton
metres (N m).
4. Reinstall the power supply.

5. Reinstall the logic board.

6. Reinstall the left speaker.

7. Reinstall the right speaker.

8. Reinstall the dual fan assembly.

9. Reinstall the chin strap.

10. Install new display panel VHB strips.

11. Reinstall the display panel.

Stand
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board
Power Supply

Tools

ESD wrist strap

Torx T10 screwdriver (magnetized)

Steps For Removal

1. Remove nine T10 screws.

T10: 923-00529

2. Lift the rear housing off of the stand, separating the stand from the mechanism.
Steps For Reassembly
1. Line up the two pins on the stand with the pin holes on the mechanism.

2. Replace the nine T10 screws in the order shown.

T10: 923-00529
3. Reinstall the power supply.

4. Reinstall the logic board.

5. Reinstall the left speaker.

6. Reinstall the right speaker.

7. Reinstall the dual fan assembly.

8. Reinstall the chin strap.

9. Install new display panel VHB strips.

10. Reinstall the display panel

Mechanism Retrieval
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Note: This procedure will need to be performed if the mechanism has retracted during customer installation of the customer-
installable VESA mount.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board
Power Supply

Tools
Service wedge (iMac)
ESD wrist strap and mat
Torx T10 screwdriver
Steps For Removal

In order to retrieve a mechanism that has retracted into the rear enclosure, it is necessary to remove all of the parts listed in
First Steps.

Steps For Reassembly

If a mechanism retracted into the rear enclosure and was retrieved via parts removal, then follow the reassembly steps in
RP1424: Stand.

Note: Customer will need to provide the stand.

Rear Housing
First Steps
Important: This procedure should only be performed by Apple-certified technicians. For more information, refer to article
OP1859: About Apple service certifications.

Remove:

Display Panel
Display Panel VHB Strips
Dual Fan Assembly
Chin Strap
Right Speaker
Left Speaker
Logic Board
Power Supply
Stand

Tools
ESD wrist strap
Lint-free cloth

Steps For Removal

When all other modules have been removed, the rear housing is the remaining part.

The rear housing includes the following parts, which are also available separately:

Mechanism (923-01906)
Mechanism screws (923-0334)
Chin strap (923-01905)
Chin strap screws (923-0338), package of 9
Fan standoff (923-02287)
Rear mic cable (923-02285)

The rear housing includes the following parts, which are not available separately:

Wi-Fi antenna (in black circle behind Apple logo)

Power button and cable
Audio cable
AC inlet
Gaskets
Wireless antenna insulator tape
Steps For Reassembly

Always handle the rear housing with two hands in the lower left and right corners. Never carry the rear housing with a single
hand, or by holding the aluminum chin (where the Apple logo appears on the lower front).

1. Reinstall the stand.

2. Reinstall the power supply.

3. Reinstall the logic board.

4. Reinstall the left speaker.

5. Reinstall the right speaker.

6. Reinstall the dual fan assembly.

7. Reinstall the chin strap.

8. Install new display panel VHB strips.

9. Reinstall the display panel.

Exploded View

Exploded View for iMac Pro (2017)

1. Display Panel, LCD

 661-08897

2. Cable, Camera/Front Mic

923-02284

3. Cable, Embedded DisplayPort (eDP)

923-02214

4. Speaker, Pair, Left and Right

923-02026

5. Logic Board

661-08867, 8-Core, VEGA56, FCC

661-08868, 8-Core, VEGA56, ETSI
661-08869, 8-Core, VEGA56, ROW
661-08871, 8-Core, VEGA64, FCC
661-08872, 8-Core, VEGA64, ETSI
661-08873, 8-Core, VEGA64, ROW
661-08875, 10-Core, VEGA56, FCC
661-08876, 10-Core, VEGA56, ETSI
661-08877, 10-Core, VEGA56, ROW
661-08879, 10-Core, VEGA64, FCC
661-08880, 10-Core, VEGA64, ETSI
661-08881, 10-Core, VEGA64, ROW
661-09633, 14-Core, VEGA56, FCC
661-09634, 14-Core, VEGA56, ETSI
661-09635, 14-Core, VEGA56, ROW
661-09637, 14-Core, VEGA64, FCC
661-09638, 14-Core, VEGA64, ETSI
661-09639, 14-Core, VEGA64, ROW
661-08883, 18-Core, VEGA56, FCC
661-08884, 18-Core, VEGA56, ETSI
661-08885, 18-Core, VEGA56, ROW
661-08887, 18-Core, VEGA64, FCC
661-08888, 18-Core, VEGA64, ETSI
661-08889, 18-Core, VEGA64, ROW

6. Flash Storage

661-08894, 1TB (2 x 512GB)

661-08895, 2TB (2 x 1TB)
661-08896, 4TB (2 x 2TB)

7. Dual Fan Assembly

923-02027

8. Memory

661-08891, 8GB, DDR4 ECC, 2666MHz

661-08892, 16GB, DDR4 ECC, 2666MHz
661-08893, 32GB, DDR4 ECC, 2666MHz

9. Cable, Power Supply Signal

923-02305

10. Power Supply

661-08944

11. Bus Bars

923-02289, GPU
923-02290, CPU
923-02288, Screws, Bus Bar to Power Supply, 5-pack
12. Upper Wi-Fi Antenna

923-01907

13. Middle Wi-Fi Antenna

923-01908

14. Lower Wi-Fi Antenna

923-01909

15. Mechanism

923-01906

16. Chin Strap

923-01905

17. Cable, Rear Mic

923-02285

18. Rear Enclosure

923-02292

19. Stand

923-02216

Tools and Fixtures

See article TP818: Required Tools.

Note:

The customer must provide a BR2032 or CR2032 coin cell battery if replacement is necessary. The batteries can no
longer be ordered.
BR2032 and CR2032 batteries have the same form factor and nominal voltage. However, BR2032 batteries have a
lower self-discharge rate and broader operating temperature range than CR2032 batteries for longer shelf and service
life.
Screw Chart

Screw Chart for iMac Pro (2017)

Note: Screws are not to scale.

923-0304 923-0331 923-0333

T8 T10
T4

Logic board (6) Right speaker (3),

Bluetooth antenna (2), Left speaker (3)
Middle Wi-Fi antenna (2),
Lower Wi-Fi antenna (2)

923-0396
923-0334 923-0338
T8
T10 Phillips #00

Mechanism (6) Chin strap (9)

Logic board (2)

923-0712 923-00609 923-00669

T8 T5 T10

Bus Bar to Power Supply, 5pk (4) Power Supply Flex Cable, 5pk (2) Fan, 5pk (4)

923-02288
923-02287
923-02215
T8
T25
T10

Bus Bar to Logic Board, 5pk (4)

Stand, 10pk (9) Fan standoff (2)
 923-02294
923-02291 923-02293
T5 T8
T5

Audio Jack Cowling (1) Power Supply, 5pk (4)

Antenna clip, 5pk (2)

923-02313

T8

Flash Storage, 5pk (2)

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