ECD SYSTEM VC Output Circuit

DESCRIPTION

The ECM constantly uses 5 V from the battery voltages supplied to the +B (BATT) terminal to operate the microprocessor. The ECM also provides this power to the sensors through the VC output circuit.

When the VC circuit is short-circuited, the microprocessor in the ECM and sensors that obtain power through the VC circuit are deactivated because power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL is not illuminated even if the system malfunctions.

Tech Tips

Under normal conditions, the MIL is illuminated for several seconds when the ignition switch is first turned to the ON position. The MIL goes off when the engine is started.

A01CH8FE61

WIRING DIAGRAM

A01CJ8GE02
A01CH70E01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK MIL


    1. Check that the Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch to the ON position.

      OK
      MIL lights up.

    OK

    GO TO MIL CIRCUIT Click here

    NG

  2. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position and turn the tester on.

    3. Check for communication between the tester and ECM.

      Result
      Result Proceed to
      Communication is possible A
      Communication is not possible B

    A

    GO TO MIL CIRCUIT Click here

    B

  3. CHECK DIESEL THROTTLE BODY (CHECK MIL ILLUMINATED)


    1. Disconnect the throttle position sensor connector.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the throttle position sensor connector.


    A

    REPLACE DIESEL THROTTLE BODY ASSEMBLY

    B

  4. CHECK ACCELERATOR PEDAL (CHECK MIL ILLUMINATED)


    1. Disconnect the accelerator pedal position sensor connector.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the accelerator pedal position sensor connector.


    A

    REPLACE ACCELERATOR PEDAL ASSEMBLY

    B

  5. CHECK CAMSHAFT POSITION SENSOR (CHECK MIL ILLUMINATED)


    1. Disconnect the connector from the camshaft position sensor.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the connector to the camshaft position sensor.


    A

    REPLACE CAMSHAFT POSITION SENSOR

    B

  6. CHECK TURBO PRESSURE SENSOR (CHECK MIL ILLUMINATED)


    1. Disconnect the connector from the turbo pressure sensor.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the connector to the turbo pressure sensor.


    A

    REPLACE TURBO PRESSURE SENSOR

    B

  7. CHECK EGR VALVE POSITION SENSOR (CHECK MIL ILLUMINATED)


    1. Disconnect the connector from the EGR valve position sensor.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the connector to the EGR valve position sensor.


    A

    REPLACE EGR VALVE ASSEMBLY (EGR VALVE POSITION SENSOR)

    B

  8. CHECK DIFFERENTIAL PRESSURE SENSOR (CHECK MIL ILLUMINATED)


    1. Disconnect the connector from the differential pressure sensor.

    2. Turn the ignition switch to the ON position.

    3. Check the MIL.

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

    4. Reconnect the connector from the differential pressure sensor.


    A

    REPLACE DIFFERENTIAL PRESSURE SENSOR

    B

  9. CHECK HARNESS AND CONNECTOR


    1. A01CH27E01

      Disconnect the throttle position sensor connector.

    2. Disconnect the accelerator pedal position sensor connector.

    3. Disconnect the camshaft position sensor connector.

    4. Disconnect the turbo pressure sensor connector.

    5. Disconnect the EGR valve position sensor connector.

    6. Disconnect the differential pressure sensor connector.

    7. Disconnect the ECM connectors.

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

      Standard resistance
      Check for short
      Tester Connections Condition Specified Conditions
      E25-21 (VCP2) - Body ground Always 10 kΩ or higher
      E25-20 (VCPA) - Body ground Always 10 kΩ or higher
      E23-22 (VCG) - Body ground Always 10 kΩ or higher
      E22-18 (VC) - Body ground Always 10 kΩ or higher

    9. Reconnect the ECM connectors.

    10. Reconnect the differential pressure sensor connector.

    11. Reconnect the EGR valve position sensor connector.

    12. Reconnect the turbo pressure sensor connector.

    13. Reconnect the camshaft position sensor connector.

    14. Reconnect the accelerator pedal position sensor.

    15. Reconnect the throttle position sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here