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










OPERATION



  • Battery voltage is applied to the throttle valve control servo relay (terminal No. 4).
  • Battery voltage is applied to the throttle valve control servo relay (terminal No. 2) from the engine control relay (terminal No. 2).
  • Engine-ECU (terminal No. 84) applies current to the throttle valve control servo relay (terminal No. 1) 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. 3) to the engine-ECU (terminal No. 72).

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
  • Battery positive voltage is higher than 8.3 V.
Judgment Criterion
  • The power line voltage of the electronic controlled throttle system should be 6.0 V or less.

PROBABLE CAUSES



  • Failed throttle valve control servo relay
  • Open/short circuit or harness damage in throttle valve control servo relay circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-21X 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 itself (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 A-21X throttle valve control servo relay connector.

  • Pull out relay and measure at relay box side.
  • Voltage between terminal No. 4 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 4 .

    Check and repair harness between battery and A-21X (terminal No. 4) throttle valve control servo relay connector.

    • Check power supply line for open/short circuit.

STEP 4. Perform voltage measurement at A-21X throttle valve control servo relay connector.

  • Pull out relay and measure at relay box side.
  • Ignition switch: ON
  • Voltage between terminal No. 2 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6 .
Go to Step 5 .

STEP 5. Connector check: A-33X engine control relay connector

Q. Is the check result normal?

    Check and repair harness between A-33X (terminal No. 2) engine control relay connector and A-21X (terminal No. 2) throttle valve control servo relay connector.

    • Check power supply line for open/short circuit.
Repair or replace the connector.

STEP 6. Connector check: B-30 engine-ECU connector

Q. Is the check result normal?
Go to Step 7 .
Repair or replace the connector.

STEP 7. Perform voltage measurement at B-30 engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Connect the terminal No. 72 of the engine-ECU harness connector to the earth.
  • Voltage between terminal No. 84 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 8 .

    Check and repair harness between A-21X (terminal No. 1) throttle valve control servo relay connector and B-30 (terminal No. 84) engine-ECU connector.

    • Check earthing line for open/short circuit.

STEP 8. Perform voltage measurement at B-30 engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Pull out A-21X throttle valve control servo relay.
  • Using a jumper wire, connect terminal No. 3 and No. 4.
  • Voltage between terminal No. 72 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 9 .

    Check and repair harness between A-21X (terminal No. 3) throttle valve control servo relay connector and B-30 (terminal No. 72) engine-ECU connector.

    • Check output line for open/short circuit.

STEP 9. Check harness between battery and A-21X (terminal No. 4) throttle valve control servo relay connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 10 .
Repair the damaged harness wire.

STEP 10. Check harness between A-33X (terminal No. 2) engine control relay connector and A-21X (terminal No. 2) throttle valve control servo relay connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Check harness between A-21X (terminal No. 1) throttle valve control servo relay connector and B-30 (terminal No. 84) engine-ECU connector.

  • Check earthing line for damage.

Q. Is the check result normal?
Go to Step 12 .
Repair the damaged harness wire.

STEP 12. Check harness between A-21X (terminal No. 3) throttle valve control servo relay connector and B-30 (terminal No. 72) engine-ECU connector.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 13 .
Repair the damaged harness wire.

STEP 13. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).