Code No. P0638: Throttle Valve Control Servo Stuck

OPERATION

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

FUNCTION

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

TROUBLE JUDGEMENT

Check Conditions

The following conditions are met for 3 seconds.

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 electrical continuity to the throttle valve control servo is discontinued.
The DPF regeneration is prohibited.
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 throttle valve control servo circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check throttle valve control servo itself.

Check throttle valve control servo itself (Refer to ).

Q. Is the check result normal?

	Go to Step 2.

	Replace the throttle body assembly.

STEP 2. Check of open circuit, short to earth, and damage in ETV+, ETV- line between throttle body assembly connector and engine-ECU connector.

Q. Are the check results normal?

	Go to Step 3.

	Repair the connector(s) or wiring harness.

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.