ECD SYSTEM VC Output Circuit

DESCRIPTION

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

A01CYQ2E02

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

Tech Tips

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

WIRING DIAGRAM

A01CY1OE02
*a Accelerator Pedal Sensor Assembly
*b Diesel Throttle Body Assembly
*c Shielded
*d Fuel Pressure Sensor (Built into Common Rail Assembly)
A01CXS4E02

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. CHECK MIL


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

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

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

    MIL does not illuminate

  2. CHECK COMMUNICATION BETWEEN GTS AND ECM


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and GTS on.

    3. Check the communication between the GTS and ECM.

      Result
      Proceed to
      Communication is not possible
      Communication is possible

    Communication is possible

    GO TO MIL CIRCUIT Click here

    Communication is not possible

  3. CHECK MIL (ACCELERATOR PEDAL SENSOR ASSEMBLY)


    1. Disconnect the accelerator pedal sensor assembly connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY Click here

    MIL does not illuminate

  4. CHECK MIL (DIESEL THROTTLE BODY ASSEMBLY)


    1. Disconnect the diesel throttle body assembly connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here

    MIL does not illuminate

  5. CHECK MIL (FUEL PRESSURE SENSOR)


    1. Disconnect the fuel pressure sensor connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE COMMON RAIL ASSEMBLY Click here

    MIL does not illuminate

  6. CHECK MIL (ELECTRIC EGR CONTROL VALVE ASSEMBLY)


    1. Disconnect the electric EGR valve assembly connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY Click here

    MIL does not illuminate

  7. CHECK MIL (DIFFERENTIAL PRESSURE SENSOR)


    1. Disconnect the differential pressure sensor assembly connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE DIFFERENTIAL PRESSURE SENSOR ASSEMBLY Click here

    MIL does not illuminate

  8. CHECK MIL (MANIFOLD ABSOLUTE PRESSURE SENSOR)


    1. Disconnect the manifold absolute pressure sensor connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

    MIL does not illuminate

  9. CHECK MIL (BATTERY CURRENT SENSOR ASSEMBLY)


    1. Disconnect the battery current sensor connector.

    2. Turn the ignition switch to ON.

    3. Check the MIL.

      Result
      Proceed to
      MIL does not illuminate
      MIL illuminates

    MIL illuminates

    REPLACE BATTERY CURRENT SENSOR ASSEMBLY Click here

    MIL does not illuminate

  10. CHECK HARNESS AND CONNECTOR


    1. Disconnect the accelerator pedal sensor assembly connector.

    2. Disconnect the diesel throttle body assembly connector.

    3. Disconnect the fuel pressure sensor connector.

    4. Disconnect the electric EGR control valve assembly connector.

    5. Disconnect the differential pressure sensor assembly connector.

    6. Disconnect the manifold absolute pressure sensor connector.

    7. Disconnect the battery current sensor connector.

    8. Disconnect the ECM connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A61-55 (VCPA) - Body ground Always 10 kΩ or higher
      A61-57 (VCP2) - Body ground Always 10 kΩ or higher
      B76-97 (VCVL) - Body ground Always 10 kΩ or higher
      B76-68 (VCM) - Body ground Always 10 kΩ or higher
      B76-69 (VCS) - Body ground Always 10 kΩ or higher
      B76-94 (VCEG) - Body ground Always 10 kΩ or higher
      B76-93 (VCPM) - Body ground Always 10 kΩ or higher
      B76-75 (VCIB) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR