Code No. P0638: Throttle Valve Control Servo Stuck

OPERATION

The electric current from the engine-ECU connector terminal ETV- and ETV+ to the electronic-controlled throttle valve control servo connector terminal is controlled.

FUNCTION

Engine-ECU checks the electronic-controlled throttle system for abnormal conditions.

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 6 - 16 V
2 seconds later after the ignition switch has been in "ON" position
The engine static state

Judgement Criterion

The difference between the objective and real openings is 5° or more.

FAIL-SAFE AND BACKUP FUNCTION

The throttle valve is opened (Electrical discontinuity).
The EGR control is stopped (fully closed).

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

STEP 1. Check throttle valve control servo itself.

Throttle body assembly connector check.
Check throttle valve control servo itself (Refer to ).

Q. Is the check result normal?

	Go to Step 2.

	Repair or replace the connector, or replace the throttle body assembly.

STEP 2. Check harness between electronic-controlled throttle valve connector and engine-ECU connector.

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

Check output line for open/short circuit and damage.

Q. Are the check results normal?

	Go to Step 3.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Replace the throttle body assembly.

After replace the throttle body assembly, re-check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU.

	The check is end.