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.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK MIL

   
   

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

      OK
      MIL lights up.

   
   

   NG

   CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM Click here

   OK

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

2. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM

   
   

   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 and turn the tester on.

   4. Check the communication between the tester and ECM.

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

   
   

   B

   GO TO MIL CIRCUIT Click here

   A

3. CHECK DIESEL THROTTLE BODY ASSEMBLY (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the throttle position sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the throttle position sensor connector.

   
   

   B

   REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here

   A

4. CHECK ACCELERATOR LINK ASSEMBLY (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the accelerator pedal position sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the accelerator pedal position sensor connector.

   
   

   B

   REPLACE ACCELERATOR LINK ASSEMBLY Click here

   A

5. CHECK CAMSHAFT POSITION SENSOR (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the camshaft position sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the camshaft position sensor connector.

   
   

   B

   REPLACE CAMSHAFT POSITION SENSOR Click here

   A

6. CHECK MANIFOLD ABSOLUTE PRESSURE SENSOR (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the manifold absolute pressure sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the manifold absolute pressure sensor connector.

   
   

   B

   REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

   A

7. CHECK EGR VALVE ASSEMBLY (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the EGR valve position sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the EGR valve position sensor connector.

   
   

   B

   REPLACE EGR VALVE ASSEMBLY (EGR VALVE POSITION SENSOR) Click here

   A

8. CHECK DIFFERENTIAL PRESSURE SENSOR (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the differential pressure sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   4. Reconnect the differential pressure sensor connector.

   
   

   B

   REPLACE DIFFERENTIAL PRESSURE SENSOR Click here

   A

9. CHECK COMMON RAIL ASSEMBLY (CHECK MIL ILLUMINATED)

   
   

   1. Disconnect the fuel pressure sensor connector.

   2. Turn the ignition switch to ON.

   3. Check the MIL.

      Result
      Result Proceed to MIL does not illuminate A MIL illuminates B

   
   

   B

   REPLACE COMMON RAIL ASSEMBLY Click here

   A

10. CHECK HARNESS AND CONNECTOR

    
    

    1. Disconnect the throttle position sensor connector.

    2. Disconnect the accelerator pedal position sensor connector.

    3. Disconnect the camshaft position sensor connector.

    4. Disconnect the manifold absolute pressure sensor connector.

    5. Disconnect the EGR valve position sensor connector.

    6. Disconnect the differential pressure sensor connector.

    7. Disconnect the fuel pressure sensor connector.

    8. Disconnect the ECM connectors.

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

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition 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

    10. Reconnect the ECM connectors.

    11. Reconnect the fuel pressure sensor connector.

    12. Reconnect the differential pressure sensor connector.

    13. Reconnect the EGR valve position sensor connector.

    14. Reconnect the manifold absolute pressure sensor connector.

    15. Reconnect the camshaft position sensor connector.

    16. Reconnect the accelerator pedal position sensor.

    17. Reconnect the throttle position sensor connector.

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here