Posted in Mitsubishi Colt

P1978 – Throttle Valve Control Servo Malfunction MMC Colt

 Posted by  Posted on September 26, 2020

OPERATION

  • Controls the current that is applied from the engine-ECU (terminals No. 7, No. 22) to the electronic-controlled throttle valve (terminals No. 1, No. 2).

    • FUNCTION

  • Engine-ECU check whether the throttle valve control servo magneto failed.

    • TROUBLE JUDGMENT

  • Battery positive voltage is 8.3 V or higher.
  • The throttle actuator driver is abnormal.

    • PROBABLE CAUSES

  • Failed throttle valve control servo.
  • Open/short circuit and damage in throttle valve control servo circuit or lose connector contact.
  • Failed engine-ECU

    • DIAGNOSIS PROCEDURE

    STEP 1. Connector check: A-118 electronic-controlled throttle valve connector

    Q. Is the check result normal?

    STEP 2. Perform resistance measurement at A-118 electronic-controlled throttle valve connector.

  • Disconnect connector, and measure at electronic-controlled throttle valve side.
  • Resistance between terminal No. 1 and No. 2.

    • Q. Is the check result normal?

    STEP 3. Connector check: A-08 engine-ECU connector

    Q. Is the check result normal?

    STEP 4. Check harness between A-118 (terminal No. 1) electronic-controlled throttle valve connector and A-08 (terminal No. 7) engine-ECU connector.

  • Check output line for short circuit and damage.

    • Q. Is the check result normal?

    STEP 5. Check harness between A-118 (terminal No. 2) electronic-controlled throttle valve connector and A-08 (terminal No. 22) engine-ECU connector.

  • Check output line for short circuit and damage.

    • Q. Is the check result normal?

    STEP 6. Check the trouble symptoms.

    Q. Is the check result normal?

    Author: admin