Code No. P0638: Throttle Valve Control Servo Circuit Range/Performance Problem










OPERATION



  • Refer to P0657 - Throttle valve control servo relay circuit malfunction .
  • Refer to P2101 - Throttle valve control servo magneto malfunction .

FUNCTION



  • Engine-A/T-ECU checks the electronic controlled throttle system for abnormal conditions.

TROUBLE JUDGMENT


Check Conditions
  • Battery voltage is more than 8.3 V.
  • Throttle position sensor (main) output voltage is 0.35 - 4.8 V.
  • Drop of throttle position sensor (main) output voltage per 100 milliseconds is more than 0.04 V.
Judgement Criterion
  • Throttle position sensor (main) output voltage has continued to be above 0.5 V higher than the target throttle position sensor (main) voltage.
Check Conditions
  • Battery voltage is more than 8.3 V.
  • Throttle position sensor (main) output voltage is 0.35 - 4.8 V.
  • Ignition switch is in "ON" position.
  • Throttle position sensor is normal.
Judgement Criterion
  • Difference is more than 1 V between actual output voltage and target voltage of throttle position sensor (main) for 4 seconds.

PROBABLE CAUSES



  • Failed throttle valve return spring.
  • Failed throttle valve operation.
  • Failed throttle valve control servo.
  • Open/short circuit in throttle valve control servo connector contact.
  • Failed engine-A/T-ECU.

DIAGNOSIS
note
    *1: L.H. drive vehicles
    *2: R.H. drive vehicles

STEP 1. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 14: Throttle position sensor (main) learning value

Q. Is the check result normal?
Go to Step 2 .
Replace the throttle body assembly.

STEP 2. Connector check: B-19X throttle valve control servo relay connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Check throttle valve control servo relay itself.

  • Check throttle valve control servo relay (Refer to ).

Q. Is the check result normal?
Go to Step 4 .
Replace the throttle valve control servo relay.

STEP 4. Perform voltage measurement at B-19X throttle valve control servo relay connector.

  • Remove relay, and measure at relay box side.
  • Voltage between terminal No. 5 and earth.
OK: System voltage

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

    Check intermediate connector A-03*1 or D-137*2, and repair if necessary. If intermediate connector is normal, check and repair harness between B-19X (terminal No. 5) throttle valve control servo relay connector and battery.

    • Check power supply line for open/short circuit.

STEP 5. Perform voltage measurement at B-19X throttle valve control servo relay connector.

  • Remove relay, and measure at relay box side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 7 .
Go to Step 6 .

STEP 6. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

    Check and repair harness between B-15X (terminal No. 1) engine control relay connector and B-19X (terminal No. 1) throttle valve control servo relay connector.

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

STEP 7. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 8 .
Repair or replace the connector.

STEP 8. Perform voltage measurement at D-212 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 15 and earth.
OK: System voltage

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

    Check and repair harness between B-19X (terminal No. 3) throttle valve control servo relay connector and D-212 (terminal No. 15) engine-A/T-ECU connector.

    • Check earthing line for open/short circuit.

STEP 9. Connector check: D-218 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 10 .
Repair or replace the connector.

STEP 10. Perform voltage measurement at D-218 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 132 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 13 .
Go to Step 11.

STEP 11. Check harness between B-19X (terminal No. 4) throttle valve control servo relay connector and D-218 (terminal No. 132) engine-A/T-ECU connector.

  • Check output line for open/short circuit.

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

STEP 12. Check harness between B-15X (terminal No. 1) engine control relay connector and B-19X (terminal No. 1) throttle valve control servo relay connector.

  • Check output line for damage.

Q. Is the check result normal?

    Check and repair harness between B-19X (terminal No. 3) throttle valve control servo relay connector and D-212 (terminal No. 15) engine-A/T-ECU connector.

    • Check earthing line for open/short circuit.
Repair the damaged harness wire.

STEP 13. Check the throttle valve control servo itself.

  • Check the throttle valve control servo itself (Refer to )

Q. Is the check result normal?
Go to Step 14 .
Replace the electronic-controlled throttle valve.

STEP 14. Connector check: B-31 electronic-controlled throttle valve connector and D-218 engine-A/T-ECU connector


Q. Are the check results normal?
Go to Step 15 .
Repair or replace the connector.

STEP 15. Check harness between B-31 (terminal No. 6) electronic-controlled throttle valve connector and D-218 (terminal No. 133) engine-A/T-ECU connector.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 16 .
Repair the damaged harness wire.

STEP 16. Check harness between B-31 (terminal No. 5) electronic-controlled throttle valve connector and D-218 (terminal No. 141) engine-A/T-ECU connector.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 17 .
Repair the damaged harness wire.

STEP 17. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

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