Code No. P0657: Throttle Valve Control Servo Relay Circuit Malfunction

OPERATION

Battery voltage is applied to the throttle valve control servo relay terminal (terminal No. 3).
Battery voltage is applied to the throttle valve control servo relay terminal (terminal No. 1) from the engine control relay (terminal No. 4).
Engine-ECU (terminal No. 123) applies current to the throttle valve control servo relay coil by turning ON the power transistor in the unit in order to turn the relay ON.
When the throttle valve control servo relay turns ON, battery voltage is supplied by the throttle valve control servo relay (terminal No. 4) to the engine-ECU (terminal No. 78).

FUNCTION

When the ignition switch ON signal is input into the engine-ECU, the engine-ECU turns ON the throttle valve control servo.

TROUBLE JUDGMENT

Check Condition

Ignition switch is in "ON" position.

Judgement Criterion

The power line voltage of the electronic-controlled throttle system is 4.0 V or less for 1 second.

PROBALE CAUSES

Failed throttle valve return spring
Open/short circuit and damage in throttle valve control servo circuit or loose connector contact.
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-221 throttle valve control servo relay connector

Q. Is the check result normal?

Go to Step 2 .

Repair or replace the connector.

STEP 2. Check throttle valve control servo relay itself.

Check throttle valve control servo relay (Refer to ).

Q. Is the check result normal?

	Go to Step 3 .

	Replace the throttle valve control servo relay.

STEP 3. Perform voltage measurement at B-221 throttle valve control servo relay connector.

Remove relay, and measure at J/B side.
Voltage between terminal No. 3 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 4 .

Check power supply line for open/short circuit.

STEP 4. Perform voltage measurement at B-221 throttle valve control servo relay connector.

Remove relay, and measure at J/B side.
Ignition switch: ON
Voltage between terminal No. 1 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 6 .

Go to Step 5 .

STEP 5. Connector check: B-206 engine control relay connector

Q. Is the check result normal?

Check power supply line for open/short circuit.

Repair or replace the connector.

STEP 6. Perform voltage measurement at A-35 engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 123 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 7 .

Check earthing line for open/short circuit.

STEP 7. Perform voltage measurement at A-35 engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 78 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 10 .

Go to Step 8 .

STEP 8. Check harness between B-221 (terminal No. 4) throttle valve control servo relay connector and A-35 (terminal No. 78) engine-ECU connector.

note

Before checking harness, check intermediate connector B-212, and repair if necessary.

Check power supply line for open/short circuit.

Q. Is the check result normal?

Go to Step 9 .

Repair the damaged harness wire.

STEP 9. Connector check: A-35 engine-ECU connector.

Check output line for damage.

Q. Is the check result normal?

Check earthing line for open/short circuit.

Repair or replace the connector.

STEP 10. Connector check: A-35 engine-ECU connector

Q. Is the check result normal?

Go to Step 11 .

Repair or replace the connector.

STEP 11. Check and repair harness between B-221 (terminal No. 3) throttle valve control servo relay connector and battery.

note

Before checking harness, check intermediate connector B-208, and repair if necessary.

Check power supply line for damage.

Q. Is the harness connector in good condition?

Go to Step 12 .

Repair the damaged harness wire.

STEP 12. Check and repair harness between B-221 (terminal No. 1) throttle valve control servo relay connector and B-206 (terminal No. 4) engine control relay connector.

Check power supply line for damage.

Q. Is the harness connector in good condition?

Go to Step 13 .

Repair the damaged harness wire.

STEP 13. Check and repair harness between B-221 (terminal No. 2) throttle valve control servo relay connector and A-35 (terminal No. 123) engine -ECU connector.

note

Before checking harness, check intermediate connector B-210, and repair if necessary.

Check power supply line for damage.

Q. Is the harness connector in good condition?

Go to Step 14 .

Repair the damaged harness wire.

STEP 14. Check and repair harness between B-221 (terminal No. 4) throttle valve control servo relay connector and A-35 (terminal No. 78) engine-ECU connector.

note

Before checking harness, check intermediate connector B-212, and repair if necessary.

Check power supply line for damage.

Q. Is the harness connector in good condition?

Go to Step 15 .

Repair the damaged harness wire.

STEP 15. M.U.T.-III diagnosis code.

Reconfirmation of diagnosis code.

Q. Is the diagnosis code set?

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).