05–251
DIAGNOSTICS – SFI SYSTEM (April, 2003) 05DIS–01
DTC P0505 IDLE AIR CONTROL SYSTEM
DTC P0511 IDLE AIR CONTROL CIRCUIT
CIRCUIT DESCRIPTION
The rotary solenoid type idle air control (IAC) valve is located
Intake Air under the throttle body and intake air bypassing the throttle
Chamber valve flows into the IAC valve through the passage.
Throttle Valve
In this way the intake air volume bypassing the throttle valve is
regulated, controls the engine speed.
From
Air
The ECM operates the IAC valve only to perform idle–up and
Cleaner provide feedback for the target idling speed.
Signal
ECM
Valve To Cylinder
IAC Valve
A58697
DTC No. DTC Detecting Condition Trouble Area
Open or short in idle air control (IAC) valve circuit
Idle air continues to vary greatly from target speed Idle air control (IAC) valve is stuck or closed
P0505
(2 trip detection logic)
A/C switch circuit
Air induction system
P0511 Open or short ISC circuit PCV valve and hose
ECM
2004 COROLLA (RM1037U)
Author: Date: 416
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
MONITOR DESCRIPTION
Idle Engine
RPM
Large
Maximum
Target RPM
Learned Value
Angle of ISC
0
Actual Idle RPM Minimum
Small
Time Time
A82389
The idle speeds are determined depending on the volume of air that passes through the IAC valve. When
the volume is large, the idle speed becomes higher. When the volume is small, the idle speed becomes lower.
The IAC valve controls the air volume that bypasses the throttle valve. The engine control module (ECM)
sends duty signals to the IAC valve and drives the IAC valve stepper motor to determine the air volume that
bypasses the throttle valve.
Although the ECM regulates the idle engine RPM with the feedback control in several vehicle stopped, actual
idle RPM does not reach the targeted RPM and a learned valve angle of the idle air control (IAC) remains
at the maximum or remains at the minimum, the ECM determines to detect malfunction in the IAC system.
Example:
If the RPM difference between the targeted and actual idle engine RPMs exceeds 200 rpm (*1) with the ve-
hicle stopped in an idle, and this occurs 5 times, or if the learned value angle of the IAC remains at its maxi-
mum or minimum angle for 5 seconds, P505 is detected.
P0511 is detected as an open/short circuit in the IAC if the rate of duty signal input to the IAC valve has stuck
at 0 or 100 %.
*1: Threshold RPM is varied by an engine load.
2004 COROLLA (RM1037U)
Author: Date: 417
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
MONITOR STRATEGY
P0505 Idle air control valve
Related DTCs
P0511 Idle air control valve
Main sensors Crankshaft position sensor
Required sensors/components Vehicle speed sensor, engine coolant tempera-
Related sensors
ture sensor
P0505 Functional check: once per driving cycle
Frequency of operation
P0505 Range check, P0511: continuous
P0505 Functional check: 10 minutes
Duration
P0505 Range check, P0511: 10 seconds
P0505 Functional check: 2 driving cycles
MIL operation
P0505 Range check, P0511: Immediately
Sequence of operation None
TYPICAL ENABLING CONDITION
Specification
Item
Minimum Maximum
The monitor will run whenever the follow-
See ”List of Disable a Monitor” (On page 05–25)
ing DTCs are not present
P0505 Functional check:
Battery voltage 11 V –
Engine coolant temperature 75C (167F) –
Idle ON (more than 6 seconds)
Vehicle speed – 1.8 mph (3 km/h)
Engine speed 400 rpm –
P0505 Range check:
Output signal duty 10 % 90 %
Battery voltage 10 V –
P0511:
Output signal duty 10 % 90 %
Battery voltage 10 V –
Time after first missing of voltage change 10 sec –
TYPICAL MALFUNCTION THRESHOLDS
Detection Criteria Threshold
P0505 Functional check:
Following conditions are met
Case1: A and B (5 times)
(At idle (after running with more than 6.2 mph (10 km/h)
Case2: B (5 seconds)
per trip)
A. Either of the following conditions is met: 1 or 2
1. Deviation of engine speed
Less than – 100 rpm or more than 200 rpm
(When shift position N or A/C ON)
2. Deviation of engine speed
Less than – 100 rpm or more than 150 rpm
(When shift position D or A/C OFF)
B. Either of the following condition is met: 1 or 2
1. IAC flow rate learning value (A/C OFF) 0.5 L/sec or less or 2.75 L/sec or more
2. IAC flow rate learning value (A/C ON) 0.22 L/sec or less or 0.98 L/sec or more
P0505 Range check:
Number of missing output voltage change 2,000 times or more
P0511:
Number of missing output voltage change 1,000 times or more
2004 COROLLA (RM1037U)
Author: Date: 418
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
COMPONENT OPERATING RANGE
Parameter Standard value
P0505, P0511:
Time while no missing voltage change 0.5 seconds or more
WIRING DIAGRAM
Instrument Instrument
Panel J/B Panel J/B
Ignition Switch
3 AM2 6 IG2 5 12
B 5 AM2 6 B–W
IM IM IL IC
B–R
10
B–W B–W
EA1
2 IA4 3
R–W B–W
EA1
B–R
1 1 1 1
ECM
2 2 EFI
5 Relay 1
EFI
1 1
MAIN
3 2
I1
1 1A 1 1 IAC Valve
B Engine
Rome J/B 5
and R/B 1 B–L RSO
DUTY E3
B
9 EA1
FL B 2
MAIN VISC
W–B
B C
3 W–B W–B
GND J5 J4
Battery
Junction
ED EC
Connector
A84938
2004 COROLLA (RM1037U)
Author: Date: 419
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
INSPECTION PROCEDURE
HINT:
When the throttle position is slightly opened (the accelerator pedal is slightly depressed) because a
floor carpet is overlapped on the accelerator pedal, or if not fully releasing the accelerator pedal, etc.,
DTC P505 will possibly be detected.
Read freeze frame data using the hand−held tester or the OBD II scan tool. Freeze frame data records
the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determin-
ing whether the vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio
was lean or rich, etc. at the time of the malfunction.
Hand–held tester:
1 CHECK OTHER DTC OUTPUT
(a) Connect the hand–held tester to the DLC3.
(b) Turn the ignition switch ON and push the hand–held tester main switch ON.
(c) Read the DTCs.
Result:
Display (DTC output) Proceed to
P0505 A
P0511 and other DTCs B
B Go to step 7
2 CHECK CONNECTION OF PCV HOSE
NG REPAIR OR REPLACE PCV HOSE
OK
3 CHECK AIR INDUCTION SYSTEM
NG REPAIR OR REPLACE
OK
2004 COROLLA (RM1037U)
Author: Date: 420
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
4 PERFORM ACTIVE TEST USING HAND–HELD TESTER(CHECK IAC VALVE
OPERATION)
(a) Warm up the engine to the normal operating temperature.
(b) Switch off all the accessories.
(c) Switch off the A/C.
(d) Shift the lever into the neutral position.
(e) Connect the hand–held tester to the DLC3.
(f) Select the item ”DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / ISC DUTY RATIO”.
(g) Check that the engine RPM varies when changing the ISC duty ratio.
Engine RPM:
Engine RPM fluctuates up and down in response to the ISC duty ratio variation.
OK CHECK FOR INTERMITTENT PROBLEMS
(See page 05–41)
NG
5 CHECK A/C SIGNAL CIRCUIT
NG REPAIR OR REPLACE
OK
6 CHECK BLOCKAGE OF IAC VALVE AND PASSAGE TO BYPASS THROTTLE
VALVE
NG REPLACE IDLE AIR CONTROL VALVE
OK
7 CHECK HARNESS AND CONNECTOR
Wire Harness Side: (a) Disconnect the I1 IAC valve connector.
ISC valve Connector (b) Turn the ignition switch ON.
I1
(c) Measure the voltage between the terminals of the IAC
valve wire harness side connector.
Standard:
1 2 3
Tester Connection Specified Condition
VISC (+) VISC (I1–2) – GND (I1–3) 9 to 14 V
Front View GND (–) (d) Reconnect the IAC valve connector.
A66264
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
2004 COROLLA (RM1037U)
Author: Date: 421
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
8 CHECK HARNESS AND CONNECTOR(IAC VALVE – ECM)
(a) Disconnect the I1 IAC valve connector.
(b) Disconnect the E3 ECM connector.
E3 (c) Check the resistance between the wire harness side con-
nectors.
Standard (Check for open):
Tester Connection Specified Condition
RSO DUTY (I1–1) – RSO (E3–5)
Below 1 Ω
E01 GND (I1–3) – E01 (E3–7)
ECM Connector A65743 Standard (Check for short):
Tester Connection Specified Condition
Wire Harness Side: DUTY (I1–1) or RSO (E3–5) – Body ground 10 kΩ or higher
ISC valve Connector (d) Reconnect the ECM connector.
I1 (e) Reconnect the IAC valve connector.
1 2 3
DUTY GND
Front View
A66264 NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
9 INSPECT IDLE AIR CONTROL VALVE (See page 10–1)
NG REPLACE IDLE AIR CONTROL VALVE
OK
REPLACE ECM (See page 10–11)
OBD II scan tool (excluding hand–held tester):
1 CHECK OTHER DTC OUTPUT
(a) Connect the hand–held tester to the DLC3.
Result:
Display (DTC output) Proceed to
P0505 A
”P0511” and other DTCs B
B Go to step 6
2004 COROLLA (RM1037U)
Author: Date: 422
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
2 CHECK CONNECTION OF PCV HOSE
NG REPAIR OR REPLACE PCV HOSE
OK
3 CHECK AIR INDUCTION SYSTEM
NG REPAIR OR REPLACE
OK
4 CHECK A/C SIGNAL CIRCUIT
NG REPAIR OR REPLACE
OK
5 CHECK BLOCKAGE OF IAC VALVE AND PASSAGE TO BYPASS THROTTLE
VALVE
NG REPAIR OR REPLACE IDLE AIR CONTROL
VALVE
OK
6 CHECK HARNESS AND CONNECTOR
Wire Harness Side: (a) Disconnect the I1 IAC valve connector.
ISC valve Connector (b) Turn the ignition switch ON.
I1
(c) Measure the voltage between the terminals of the IAC
valve wire harness side connector.
Standard:
1 2 3
Tester Connection Specified Condition
VISC (+) VISC (I1–2) – GND (I1–3) 9 to 14 V
Front View GND (–) (d) Reconnect the IAC valve connector.
A66264
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
2004 COROLLA (RM1037U)
Author: Date: 423
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DIAGNOSTICS – SFI SYSTEM (April, 2003)
7 CHECK HARNESS AND CONNECTOR(IAC VALVE – ECM)
(a) Disconnect the I1 IAC valve connector.
(b) Disconnect the E3 ECM connector.
E3 (c) Check the resistance between the wire harness side con-
nectors.
Standard (Check for open):
Tester Connection Specified Condition
RSO DUTY (I1–1) – RSO (E3–5)
Below 1 Ω
E01 GND (I1–3) – E01 (E3–7)
ECM Connector A65743 Standard (Check for short):
Tester Connection Specified Condition
Wire Harness Side: DUTY (I1–1) or RSO (E3–5) – Body ground 10 kΩ or higher
ISC valve Connector (d) Reconnect the ECM connector.
I1 (e) Reconnect the IAC valve connector.
1 2 3
DUTY GND
Front View NG REPAIR OR REPLACE HARNESS OR
A66264
CONNECTOR
OK
8 INSPECT IDLE AIR CONTROL VALVE (See page 10–1)
NG REPAIR OR REPLACE IDLE AIR CONTROL
VALVE
OK
REPLACE ECM(See page 10–11)
2004 COROLLA (RM1037U)
Author: Date: 424
