Inspection Procedure 30: Idle Speed Control Servo System

OPERATION

The power is supplied to the idle speed control servo (terminal No. 2 and No. 5) from the engine control relay (terminal No. 1).

The engine-A/T-ECU (terminal No. 14, No. 15, No. 28 and No. 29) makes power transistor in the unit be in "ON" position in order, and that makes currents go on the idle speed control servo (terminal No. 1, No. 3, No. 4 and No. 6).

FUNCTION

The idle speed control servo opens and closes the servo valve in response to a signal from the engine-A/T-ECU to control the intake air flow rate during idling.

PROBABLE CAUSE

Failed idle speed control servo

Open/short circuit in idle speed control servo circuit or loose connector contact

Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. MUT-II/III Data List

Refer to Data list reference table .

Item 45: Idle speed control servo

Q: Is the check result normal?

YES: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

).
NO: Go to Step 2

STEP 2. Connector check: B-105 idle speed control servo connector

Q: Is the check result normal?

YES: Go to Step 3

.
NO: Repair.

STEP 3. Check idle speed control servo itself.

Check idle speed control servo itself (Refer to ).

Q: Is the check result normal?

YES: Go to Step 4

.
NO: Replace idle speed control servo.

STEP 4. Perform voltage measurement at B-105 idle speed control servo connector.

Disconnect connector, and measure at harness side.

Ignition switch: ON

Voltage between terminal No. 2 and earth, also between terminal No. 5 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 6

.
NO: Go to Step 5

STEP 5. Connector check: B-17X engine control relay connector

Q: Is the check result normal?

YES:

Check and repair harness between B-105 (terminal No. 2 or No. 5) idle speed control servo connector and B-17X (terminal No. 1) engine control relay connector.

Check power supply line for open/short circuit.

NO: Repair.

STEP 6. Perform voltage measurement at C-112 engine-A/T-ECU connector.

Disconnect connector, and measure at harness side.

Ignition switch: ON

Voltage between terminal No. 14 and earth, between terminal No. 15 and earth, between terminal No. 28 and earth, also voltage between terminal No. 29 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 7

.
NO:

Check and repair harness between B-105 idle speed control servo and C-112 engine-A/T-ECU.

Harness between idle speed control servo terminal No. 1 and engine-A/T-ECU connector terminal No. 14

Harness between idle speed control servo terminal No. 3 and engine-A/T-ECU connector terminal No. 28

Harness between idle speed control servo terminal No. 4 and engine-A/T-ECU connector terminal No. 15

Harness between idle speed control servo terminal No. 6 and engine-A/T-ECU connector terminal No. 29

Check power supply line for open/short circuit.

STEP 7. Connector check: C-112 engine-A/T-ECU connector

Q: Is the check result normal?

YES: Go to Step 8

.
NO: Repair.

STEP 8. Check harness between B-105 idle speed control servo and C-112 engine-A/T-ECU.

Harness between idle speed control servo terminal No. 1 and engine-A/T-ECU connector terminal No. 14

Harness between idle speed control servo terminal No. 3 and engine-A/T-ECU connector terminal No. 28

Harness between idle speed control servo terminal No. 4 and engine-A/T-ECU connector terminal No. 15

Harness between idle speed control servo terminal No. 6 and engine-A/T-ECU connector terminal No. 29

Check output line for damage.

Q: Are the check results normal?

YES: Go to Step 9

.
NO: Repair.

STEP 9. Check harness between B-105 (terminal No. 2 or No. 5) idle speed control servo connector and B-17X (terminal No. 1) engine control relay connector.

Check power supply line for damage.

Q: Is the check result normal?

YES: Go to Step 10

.
NO: Repair.

STEP 10. MUT-II/III Data List

Refer to Data list reference table .

Item 45: Idle speed control servo

Q: Is the check result normal?

YES: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

).
NO: Replace engine-A/T-ECU.


Inspection Procedure 30: Idle Speed Control Servo System

OPERATION The power is supplied to the idle speed control servo (terminal No. 2 and No. 5) from the engine control relay (terminal No. 1). The engine-A/T-ECU (terminal No. 14, No. 15, No. 28 and No. 29) makes power transistor in the unit be in "ON" position in order, and that makes currents go on the idle speed control servo (terminal No. 1, No. 3, No. 4 and No. 6).
FUNCTION The idle speed control servo opens and closes the servo valve in response to a signal from the engine-A/T-ECU to control the intake air flow rate during idling.
PROBABLE CAUSE Failed idle speed control servo Open/short circuit in idle speed control servo circuit or loose connector contact Failed engine-A/T-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. MUT-II/III Data List Refer to Data list reference table . Item 45: Idle speed control servo Q: Is the check result normal? YES: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ). NO: Go to Step 2 .
	STEP 2. Connector check: B-105 idle speed control servo connector
	Q: Is the check result normal? YES: Go to Step 3 . NO: Repair.
	STEP 3. Check idle speed control servo itself. Check idle speed control servo itself (Refer to ). Q: Is the check result normal? YES: Go to Step 4 . NO: Replace idle speed control servo.
	STEP 4. Perform voltage measurement at B-105 idle speed control servo connector.
	Disconnect connector, and measure at harness side. Ignition switch: ON Voltage between terminal No. 2 and earth, also between terminal No. 5 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 6 . NO: Go to Step 5 .
	STEP 5. Connector check: B-17X engine control relay connector
	Q: Is the check result normal? YES: Check and repair harness between B-105 (terminal No. 2 or No. 5) idle speed control servo connector and B-17X (terminal No. 1) engine control relay connector. Check power supply line for open/short circuit. NO: Repair.
	STEP 6. Perform voltage measurement at C-112 engine-A/T-ECU connector.
	Disconnect connector, and measure at harness side. Ignition switch: ON Voltage between terminal No. 14 and earth, between terminal No. 15 and earth, between terminal No. 28 and earth, also voltage between terminal No. 29 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 7 . NO: Check and repair harness between B-105 idle speed control servo and C-112 engine-A/T-ECU. Harness between idle speed control servo terminal No. 1 and engine-A/T-ECU connector terminal No. 14 Harness between idle speed control servo terminal No. 3 and engine-A/T-ECU connector terminal No. 28 Harness between idle speed control servo terminal No. 4 and engine-A/T-ECU connector terminal No. 15 Harness between idle speed control servo terminal No. 6 and engine-A/T-ECU connector terminal No. 29 Check power supply line for open/short circuit.
	STEP 7. Connector check: C-112 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Go to Step 8 . NO: Repair.
	STEP 8. Check harness between B-105 idle speed control servo and C-112 engine-A/T-ECU.
	Harness between idle speed control servo terminal No. 1 and engine-A/T-ECU connector terminal No. 14 Harness between idle speed control servo terminal No. 3 and engine-A/T-ECU connector terminal No. 28 Harness between idle speed control servo terminal No. 4 and engine-A/T-ECU connector terminal No. 15 Harness between idle speed control servo terminal No. 6 and engine-A/T-ECU connector terminal No. 29 Check output line for damage. Q: Are the check results normal? YES: Go to Step 9 . NO: Repair.
	STEP 9. Check harness between B-105 (terminal No. 2 or No. 5) idle speed control servo connector and B-17X (terminal No. 1) engine control relay connector.
	Check power supply line for damage. Q: Is the check result normal? YES: Go to Step 10 . NO: Repair.
	STEP 10. MUT-II/III Data List Refer to Data list reference table . Item 45: Idle speed control servo Q: Is the check result normal? YES: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ). NO: Replace engine-A/T-ECU.