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

OPERATION

Refer to P0657 - Throttle valve control servo circuit .
Refer to P2101 - Throttle valve control servo circuit .

FUNCTION

Engine-ECU <M/T> or engine-A/T-ECU <A/T> checks the electronic controlled throttle system for abnormal conditions.

TROUBLE JUDGMENT

Check Conditions

Battery positive voltage is 8.3 V or higher.
Throttle position sensor (main) output voltage is 0.35 - 4.8 V.
Drop of throttle position sensor (main) output voltage per 100 milliseconds is 0.04 V or more.

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 positive voltage is 8.3 V or higher.
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 between throttle position sensor (main) output voltage and target throttle position sensor (main) voltage is 1 V or higher 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 circuit or loose connector contact.
Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>.

DIAGNOSIS

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

Refer to Data List Reference Table .

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 .

	Repair 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 <L.H. drive vehicles> or D-137 <R.H. drive vehicles>, 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. Perform voltage measurement at D-243 engine-ECU <M/T> connector or D-212 engine-A/T-ECU <A/T> 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 8 .

	Check and repair harness between B-19X (terminal No. 3) throttle valve control servo relay connector and D-243 (terminal No. 15) engine-ECU <M/T> connector or D-212 (terminal No. 15) engine-A/T-ECU <A/T> connector. Check earthing line for open/short circuit.

STEP 8. Perform voltage measurement at D-247 engine-ECU <M/T> connector or D-218 engine-A/T-ECU <A/T> 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 11 .

	Go to Step 9 .

STEP 9. Check harness between B-19X (terminal No. 4) throttle valve control servo relay connector and D-247 (terminal No. 132) engine-ECU <M/T> connector or D-218 (terminal No. 132) engine-A/T-ECU <A/T> connector.

Check output line for open/short circuit.

Q. Is the check result normal?

	Go to Step 10 .

	Repair the damaged harness wire.

STEP 10. 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-243 (terminal No. 15) engine-ECU <M/T> connector or D-212 (terminal No. 15) engine-A/T-ECU <A/T> connector. Check earthing line for open/short circuit.

	Repair the damaged harness wire.

STEP 11. Connector check: D-243 and D-247 engine-ECU <M/T> connector or D-212 and D-218 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

	Go to Step 12 .

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

STEP 12. Check the throttle valve control servo itself.

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

Q. Is the check result normal?

	Go to Step 13 .

	Replace the electronic-controlled throttle valve.

STEP 13. Connector check: B-31 electronic-controlled throttle valve connector and D-247 engine-ECU <M/T> connector or D-218 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

	Go to Step 14 .

	Repair or replace the connector.

STEP 14. Check harness between B-31 (terminal No. 6) electronic-controlled throttle valve connector and D-247 (terminal No. 133) engine-ECU <M/T> connector or D-218 (terminal No. 133) engine-A/T-ECU <A/T> connector.

Check output line for short circuit and damage.

Q. Is the check result normal?

	Go to Step 15 .

	Repair the damaged harness wire.

STEP 15. Check harness between B-31 (terminal No. 5) electronic-controlled throttle valve connector and D-247 (terminal No. 141) engine-ECU <M/T> connector or D-218 (terminal No. 141) engine-A/T-ECU <A/T> connector.

Check output line for short circuit and damage.

Q. Is the check result normal?

	Go to Step 16 .

	Repair the damaged harness wire.

STEP 16. Check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU <M/T> or engine-A/T-ECU <A/T>.

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