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.

B001IBAE71

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 to ON. The MIL goes off when the engine is started.

WIRING DIAGRAM


B001DVGE04
*a Accelerator Pedal Position Sensor
*b Throttle Position Sensor
*c Fuel Pressure Sensor
B001DUNE02

CAUTION / NOTICE / HINT

Note


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

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

PROCEDURE


  1. CHECK COMMUNICATION BETWEEN INTELLIGENT TESTER AND ECM


    1. Connect the intelligent tester to the DLC3.

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

    3. Check the communication between the tester and ECM.

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

    A

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

    B

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ECM)


    1. Turn the ignition switch to ON.

    2. B001CC1E03
      Text in Illustration
      *a Component with harness connected (ECM)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G57-24 (+B) - Body ground Ignition switch ON 11 to 14 V
      G57-17 (+B2) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If the result is not as specified, since current is not flowing to the +B and +B2 terminals of the ECM, the system may not be started.


    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  3. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (ACCELERATOR PEDAL POSITION SENSOR)


    1. Disconnect the accelerator pedal position sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

      Tech Tips

      It can be checked using the "Engine" item of the Data List.


    A

    REPLACE ACCELERATOR PEDAL ROD ASSEMBLY Click here

    B

  4. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (THROTTLE POSITION SENSOR)


    1. Disconnect the throttle position sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

    A

    REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here

    B

  5. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (FUEL PRESSURE SENSOR)


    1. Disconnect the fuel pressure sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

      Tech Tips

      It can be checked using the "Engine" item of the Data List.


    A

    REPLACE COMMON RAIL Click here

    B

  6. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (EGR VALVE POSITION SENSOR)


    1. Disconnect the EGR valve position sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

      Tech Tips

      It can be checked using the "Engine" item of the Data List.


    A

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY Click here

    B

  7. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (MANIFOLD ABSOLUTE PRESSURE SENSOR)


    1. Disconnect the manifold absolute pressure sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

      Tech Tips

      It can be checked using the "Engine" item of the Data List.


    A

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

    B

  8. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM (NOZZLE VANE POSITION SENSOR)


    1. Disconnect the nozzle vane position sensor connector.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Check the communication between the intelligent tester and ECM.

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

      Tech Tips

      It can be checked using the "Engine" item of the Data List.


    A

    REPLACE TURBOCHARGER SUB-ASSEMBLY Click here

    B

  9. CHECK HARNESS AND CONNECTOR


    1. Disconnect the accelerator pedal position sensor connector.

    2. Disconnect the throttle position sensor connector.

    3. Disconnect the fuel pressure sensor connector.

    4. Disconnect the EGR position sensor connector.

    5. Disconnect the nozzle vane position sensor connector.

    6. Disconnect the manifold absolute pressure sensor connector.

    7. Disconnect the ECM connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G58-6 (VCPA) - Body ground Always 10 kΩ or higher
      G58-4 (VCP2) - Body ground Always 10 kΩ or higher
      C91-8 (VCVL) - Body ground Always 10 kΩ or higher
      C90-14 (VCM) - Body ground Always 10 kΩ or higher
      C90-13 (VCS) - Body ground Always 10 kΩ or higher
      C91-13 (VCEG) - Body ground Always 10 kΩ or higher
      C91-12 (VCPM) - Body ground Always 10 kΩ or higher
      C91-11 (VNVC) - Body ground Always 10 kΩ or higher
      G57-24 (+B) - Body ground Always 10 kΩ or higher
      G57-17 (+B2) - Body ground Always 10 kΩ or higher

    9. Reconnect the accelerator pedal position sensor connector.

    10. Reconnect the throttle position sensor connector.

    11. Reconnect the fuel pressure sensor connector.

    12. Reconnect the EGR position sensor connector.

    13. Reconnect the nozzle vane position sensor connector.

    14. Reconnect the manifold absolute pressure sensor connector.

    15. Reconnect the ECM connectors.


    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR