P0638 – Throttle Valve Control Servo Stuck MMC L200 IV



OPERATION

  • The electric current from the engine- ECU (terminal No. 129 and No. 114) to the throttle valve control servo (terminal No. 5 and No. 6) is controlled.

  • FUNCTION

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

  • TROUBLE JUDGMENT

  • Battery positive voltage is 6 – 16 V.
  • 2 seconds later after the ignition switch has been in “ON” position.
  • The engine static state.
  • The difference between the objective and real openings is 10° or more for 0.5 second.

  • PROBABLE CAUSES

  • Failed throttle valve return spring
  • Failed throttle valve operation
  • Failed throttle valve control servo
  • Throttle valve control servo circuit harness damage or loose connector contact
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

    STEP 1. Connector check: A-132 electronic-controlled throttle valve connector

    Q. Is the check result normal?

    STEP 2. Check throttle valve control servo itself.

    Q. Is the check result normal?

    STEP 3. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

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

  • Check harness between A-132 (terminal No.5) electronic-controlled throttle valve connector and C-103 (terminal No.129) engine-ECU connector.
  • Check harness between A-132 (terminal No.6) electronic-controlled throttle valve connector and C-103 (terminal No.114) engine-ECU connector.
  • Check output line for damage.
  • Q. Are the check results normal?

    STEP 5. Replace the electronic-controlled throttle valve assembly.

  • After replace the electronic-controlled throttle valve assembly, re-check the trouble symptoms.
  • Q. Does trouble symptom persist?

    Author: admin