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




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion
Check Conditions
Judgement Criterion
Check Conditions
Judgement Criterion
Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. Check throttle body.



  • Check whether the throttle valve return spring is normal.

Q. Is the check result normal?

Go to Step 2.
Replace the throttle body assembly.

STEP 2. Check throttle valve control servo itself.



  • Electronic-controlled throttle valve connector check.
  • Throttle valve control servo check (Refer to ).

Q. Is the check result normal?

Go to Step 3.
Repair or replace the connector, or replace the throttle body assembly.

STEP 3. Check harness between electronic-controlled throttle valve connector terminal and engine-ECU connector terminal ETV+.



  • Check signal line for damage.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Check harness between electronic-controlled throttle valve connector terminal and engine-ECU connector terminal ETV-.



  • Check output line for damage.

Q. Is the check result normal?

Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.

Q. Is diagnosis code stored?

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