ECD SYSTEM MIL Circuit

DESCRIPTION

The Malfunction Indicator Lamp (MIL) is used to indicate vehicle malfunctions detected by the ECM. By turning the ignition switch to ON, power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually. When the ignition switch is first turned to ON, the MIL should illuminate and should then turn off. If the MIL remains illuminated or does not illuminate, conduct the following troubleshooting procedure. If the ECM detects any trouble, the MIL illuminates. At this time, the ECM records a DTC in the memory.

WIRING DIAGRAM

A01CHWDE02

INSPECTION PROCEDURE

Note


  • After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. CHECK THAT MIL ILLUMINATES


    1. Turn the ignition switch to ON.

    2. Check the illumination of the MIL.

      Result
      Result Proceed to
      MIL remains illuminated (Even after ignition switch is turned to ON and several seconds have passed, MIL still remains illuminated) A
      MIL remains off (Does not illuminate at all) B
      MIL illuminates for several seconds, but turns off after engine is started C

    B

    CHECK IF ENGINE STARTS Click here

    C

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    A

  2. CHECK WHETHER MIL TURNS OFF


    1. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the tester on.

    5. Enter the following menus: Powertrain / Engine and ECT / DTC.

    6. Check if any DTCs have been stored. Note any DTCs.

    7. Clear the DTCs Click here.

    8. Check if the MIL goes off.

      Result
      Result Proceed to
      MIL goes off A
      MIL does not go off B

    B

    CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS) Click here

    A

    REPAIR CIRCUIT INDICATED BY OUTPUT DTC

  3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)


    1. A01CGMCE07
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

    3. Check if the MIL is illuminated.

      Result
      Result Proceed to
      MIL is not illuminated A
      MIL is illuminated B

    4. Reconnect the ECM connector.


    B

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM) Click here

    A

    REPLACE ECM Click here

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)


    1. Disconnect the combination meter assembly connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C18-34 (CHK) or E39-19 (W) - Body ground Always 10 kΩ or higher

    4. Reconnect the combination meter assembly connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

    OK

    REPLACE COMBINATION METER ASSEMBLY

  5. CHECK IF ENGINE STARTS


    1. Start the engine.

      Result
      Result Proceed to
      Engine starts A
      Engine does not start* B

      Tech Tips

      *: The intelligent tester cannot communicate with the ECM.


    B

    GO TO VC OUTPUT CIRCUIT Click here

    A

  6. CHECK HARNESS AND CONNECTOR (ECM TERMINAL VOLTAGE)


    1. A01CGMCE06
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      E39-19 (W) - Body ground Ignition switch ON 18 to 27 V

    4. Reconnect the ECM connector.


    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM) Click here

    OK

    REPLACE ECM Click here

  7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)


    1. Disconnect the combination meter assembly connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      C18-34 (CHK) - E39-19 (W) Always Below 1 Ω

    4. Reconnect the ECM connector.

    5. Reconnect the combination meter assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

    OK

    REPLACE COMBINATION METER ASSEMBLY