05–218

DIAGNOSTICS – SFI SYSTEM 05DJX–01

DTC P0505 IDLE AIR CONTROL SYSTEM

DTC P0511 IDLE AIR CONTROL CIRCUIT

CIRCUIT DESCRIPTION
The rotary solenoid type idle speed control (ISC) valve is lo-
Intake Air cated under the throttle body and intake air bypassing the
Chamber throttle valve flows to the idle speed control (ISC) valve through
Throttle Valve
the passage.
From
In this way the intake air volume bypassing the throttle valve is
Air regulated, controls the engine speed.
Cleaner The ECM operates the idle speed control (ISC) valve only to
perform idle–up and provide feedback for the target idling
Signal
speed.
ECM

Valve To Cylinder
ISC Valve
A58697

DTC No. DTC Detecting Condition Trouble Area

Open or short in idle speed control (ISC) valve circuit
P0505 Idle speed continues to vary greatly from target speed

Idle speed control (ISC) valve is stuck or closed

ECM
P0511 Open or short ISC circuit
Air induction system

PCV valve and hose

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 378

 05–219
DIAGNOSTICS – SFI SYSTEM

MONITOR DESCRIPTION

Large
Target RPM Maximum
Idle Engine Learned Value
RPM of the idle speed
control
0

Actual Idle RPM Minimum

Small

Time Time

A82389

The idle speed is determined depending on the volume of air that passes through the ISC valve. When the
volume is large, the idle speed is higher. When the volume is small, the idle speed is lower. The ISC valve
controls the volume of air that bypasses the throttle valve. The engine control module (ECM) sends duty
signals to the ISC valve and drives the ISC valve to determine the volume of air that bypasses the throttle
valve.
Although the ECM regulates the idle engine RPM with the feedback control in several vehicle stopped, actual
idle RPM dose not reach the targeted RPM and a learned valve angle of the idle speed control (ISC) remains
at the maximum or remains at the minimum, the ECM determines to detect malfunction in the ISC system.
If the rate of duty signal input to the ISC valve is stuck to 0 or 100 %, the ECM interprets it as an open/short
circuit in the ISC valve and sets a DTC.
Example:
If then RPM difference between the target RPM and actual RPM exceeds 200 rpm (*1) with the vehicle
stopped in the idle and this occurs 5 times.
*1: The threshold is varied by an engine load.

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 379

05–220
DIAGNOSTICS – SFI SYSTEM

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 min
Duration
P0505 Range check, P0511: 10 sec
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” table (On page 05–24)
ing DTCs are not present
P0505 Functional check:
Battery voltage 11 V –
Engine coolant temperature 75C (167F) –
Idle ON (more than 6 sec)
Vehicle speed – 3 km/h (2 mph)
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 at idle (after running with more
A, B and C
than 6.2 mph (10 km/h)) per trip:
A. Either following condition 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)
–0.07 L/sec or less or 0.75 L/sec or more (A/C OFF)
B. IAC flow rate learning value
0.38 L/sec or less or 1.88 L/sec or more (A/C ON)
C. Number of detections 5 times/trip
P0505 Range check:
Missing output duty voltage
P0511:
Number of missing output voltage change 1000 times or more

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 380

 05–221
DIAGNOSTICS – SFI SYSTEM

COMPONENT OPERATING RANGE

Parameter Standard Value
P0511:
Time while no missing voltage change 0.5 sec or more

WIRING DIAGRAM
I10
Ignition Switch
5 6
AM2 IG2
W–R B

1 1O 6 1O

2
7 1A 3 1A
Instrument Panel J/B
W–R B–R
B–Y

1 1 1 1

2 2 5 1
AM2 EFI EFI
1 1 Relay
3 2
ECM
1 1 1 I1
Engine ISC Valve
Room R/B 4 5
B–L B–Y B 2 1 B–R RSD
EA1 VISC DUTY E5
3
F8
7
MAIN Fusible 3 BR BR
GND E5 E01
Limk Block
W–B
BR

Battery
EB ED

A83866

INSPECTION PROCEDURE
HINT:
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 determining 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.

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 381

05–222
DIAGNOSTICS – SFI SYSTEM

Hand–held tester:
1 CHECK CONNECTION OF PCV HOSE

NG REPAIR OR REPLACE PCV HOSE

OK

2 CHECK AIR INDUCTION SYSTEM

NG REPAIR OR REPLACE

OK

3 CHECK OTHER DTCS 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) Select the item ”DIAGNOSIS / OBD/MOBD / DTC INFO / CURRENT CODES”.
(d) Read the DTCs using the hand–held tester.
Result:
Display (DTC output) Proceed to
Only ”P0505” is output A
”P0505” and other DTCs are output B
HINT:
If any other codes besides ”P0505” is output, perform the troubleshooting for those DTCs first.
B Go to step 7

4 PERFORM ACTIVE TEST USING HAND–HELD TESTER(CHECK ISC VALVE

OPERATION)

(a) Connect the hand–held tester to the DLC3 on the vehicle.

(b) Warm up the engine to the normal operating temperature.
(c) Switch off all the accessories.
(d) Switch off the A/C.
(e) Shift the lever into the neutral position.
(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 respose to the ISC duty ratio variation.
OK CHECK FOR INTERMITTENT PROBLEMS
(See page 05–41)

NG

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 382

 05–223
DIAGNOSTICS – SFI SYSTEM

5 CHECK A/C SIGNAL CIRCUIT

NG REPAIR OR REPLACE

OK

6 CHECK BLOCKAGE OF ISC VALVE AND PASSAGE TO BYPASS THROTTLE

VALVE

NG REPAIR OR REPLACE THLOTTLE BODY IDLE

SPEED CONTROL VALVE ASSY

OK

7 CHECK HARNESS AND CONNECTOR

Wire Harness Side (a) Disconnect the I1 ISC valve connector.

ISC valve Connector (b) Turn the ignition switch ON.
I1
(c) Measure the voltage between the terminals of the ISC
valve wire harness side connector.
Standard:
1 2 3
Tester Connection Specified Condition
+B (I1–2) – GND (I1–3) 9 to 14 V
+B (+) GND (–) (d) Reconnect the ISC valve connector.
Front View A66264
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR

OK

8 CHECK HARNESS AND CONNECTOR(ISC VALVE – ECM)

(a) Disconnect the I1 ISC valve connector.

(b) Disconnect the E5 ECM connector.
E5 (c) Measure the resistance between the wire harness side
connectors.
Standard (Check for open):
Tester Connection Specified Condition
RSD DUTY (I1–1) – RSD (E5–5)
E01 Below 1 Ω
GND (I1–3) – E01 (E5–7)
ECM Connector A65743 Standard (Check for short):
Tester Connection Specified Condition
Wire Harness Side DUTY (I1–1) or RSD (E5–5) – Body groundr 10 kΩ or higher

I1 ISC valve Connector (d) Reconnect the ISC valve connector.

(e) Reconnect the ECM connector.

1 2 3

DUTY GND
Front View A66264
2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 383

05–224
DIAGNOSTICS – SFI SYSTEM

NG REPAIR OR REPLACE HARNESS OR

CONNECTOR

OK

9 INSPECT THLOTTLE BODY IDLE SPEED CONTROL VALVE ASSY

(See page 10–1)

NG REPLACE THLOTTLE BODY IDLE SPEED

CONTROL VALVE ASSY

OK

REPLACE ECM (See page 10–17)

OBD II scan tool (excluding hand–held tester):

1 CHECK CONNECTION OF PCV HOSE

NG REPAIR OR REPLACE PCV HOSE

OK

2 CHECK AIR INDUCTION SYSTEM

NG REPAIR OR REPLACE

OK

3 CHECK OTHER DTCS OUTPUT

(a) Connect the OBD II scan tool to the DLC3.

(b) Turn the ignition switch ON and push the OBD II scan tool main switch ON.
(c) Select the item ”DIAGNOSIS / OBD/MOBD / DTC INFO / CURRENT CODES”.
(d) Read the DTCs using the OBD II scan tool.
Result:
Display (DTC output) Proceed to
Only ”P0505” is output A
”P0505” and other DTCs are output B

HINT:
If any other codes besides ”P0505” is output, perform the troubleshooting for those DTCs first.
B Go to step 7

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 384

 05–225
DIAGNOSTICS – SFI SYSTEM

4 CHECK A/C SIGNAL CIRCUIT

NG REPAIR OR REPLACE

OK

5 CHECK BLOCKAGE OF ISC VALVE AND PASSAGE TO BYPASS THROTTLE

VALVE

NG REPAIR OR REPLACE THLOTTLE BODY IDLE

SPEED CONTROL VALVE ASSY

OK

6 CHECK HARNESS AND CONNECTOR

Wire Harness Side (a) Disconnect the I1 ISC valve connector.

ISC valve Connector (b) Turn the ignition switch ON.
I1
(c) Measure the voltage between the terminals of the ISC
valve wire harness side connector.
Standard:
1 2 3
Tester Connection Specified Condition
+B (I1–2) – GND (I1–3) 9 to 14 V
+B (+) GND (–) (d) Reconnect the ISC valve connector.
Front View A66264
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR

OK

7 CHECK HARNESS AND CONNECTOR(ISC VALVE – ECM)

(a) Disconnect the I1 ISC valve connector.

(b) Disconnect the E5 ECM connector.
E5 (c) Measure the resistance between the wire harness side
connectors.
Standard (Check for open):
Tester Connection Specified Condition
RSD DUTY (I1–1) – RSD (E5–5)
E01 Below 1 Ω
GND (I1–3) – E01 (E5–7)
ECM Connector A65743 Standard (Check for short):
Tester Connection Specified Condition
Wire Harness Side DUTY (I1–1) or RSD (E5–5) – Body groundr 10 kΩ or higher

I1 ISC valve Connector (d) Reconnect the ISC valve connector.

(e) Reconnect the ECM connector.

1 2 3

DUTY GND
Front View A66264
2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 385

05–226
DIAGNOSTICS – SFI SYSTEM

NG REPAIR OR REPLACE HARNESS OR

CONNECTOR

OK

8 INSPECT THLOTTLE BODY IDLE SPEED CONTROL VALVE ASSY

(See page 10–1)

NG REPLACE THLOTTLE BODY IDLE SPEED

CONTROL VALVE ASSY

OK

REPLACE ECM (See page 10–17)

2004 SCION xB REPAIR MANUAL (RM1031U)

Author: Date: 386