SFI SYSTEM VC Output Circuit

DESCRIPTION

The ECM constantly generates 5 V power source voltage from the battery voltages supplied to the +B, +B2 (BATT) terminals to operate the microprocessor. The ECM also provides this power to the sensors through the VC output circuit.

B003S7NE27

When the VC circuit has a short circuit, the CPU in the ECM and sensors that are supplied power through the VC circuit are deactivated because power is not supplied from the VC circuit. When the system is in this condition, it will not start.

WIRING DIAGRAM

Figure 1. VC Power Source Circuit

B003RLFE03
*a VVT Sensor (for Intake Camshaft of Bank 1)
*b VVT Sensor (for Intake Camshaft of Bank 2)
*c Throttle Body with Motor Assembly
*d Accelerator Pedal Sensor Assembly

For the circuit diagram of the ECM power source circuit.

Click here

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. CHECK COMMUNICATION BETWEEN GTS AND ECM


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Check the communication between the GTS and ECM.

      Tech Tips

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

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

    B

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

    A

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ECM)


    1. B003JTKC03
      *a Rear view of wire harness connector (to ECM)

      Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G144-23 (+B) - Body ground Ignition switch ON 11 to 14 V
      G144-22 (+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.

      Result
      Proceed to
      OK
      NG

    NG

    GO TO ECM POWER SOURCE CIRCUIT Click here

    OK

  3. CHECK THROTTLE BODY WITH MOTOR ASSEMBLY (CHECK FOR SHORT IN THROTTLE POSITION SENSOR)


    1. Disconnect the throttle body with motor assembly connector.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Check the communication between the GTS and ECM.

      Tech Tips

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

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

      Tech Tips

      Perform "Inspection After Repair" after replacing the throttle body with motor assembly.

      Click here


    B

    REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY Click here

    A

  4. CHECK ACCELERATOR PEDAL SENSOR ASSEMBLY (CHECK FOR SHORT IN ACCELERATOR PEDAL SENSOR)


    1. Disconnect the accelerator pedal sensor assembly connector.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Check the communication between the GTS and ECM.

      Tech Tips

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

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

    B

    REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY Click here

    A

  5. CHECK VVT SENSOR (CHECK FOR SHORT IN VVT SENSOR (FOR INTAKE CAMSHAFT OF BANK 1))


    1. Disconnect the VVT sensor (for intake camshaft of bank 1) connector.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Check the communication between the GTS and ECM.

      Tech Tips

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

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

    B

    REPLACE VVT SENSOR (FOR INTAKE CAMSHAFT OF BANK 1) Click here

    A

  6. CHECK VVT SENSOR (CHECK FOR SHORT IN VVT SENSOR (FOR INTAKE CAMSHAFT OF BANK 2))


    1. Disconnect the VVT sensor (for intake camshaft of bank 2) connector.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Check the communication between the GTS and ECM.

      Tech Tips

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

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

    B

    REPLACE VVT SENSOR (FOR INTAKE CAMSHAFT OF BANK 2) Click here

    A

  7. CHECK HARNESS AND CONNECTOR (VC CIRCUIT)


    1. Disconnect the throttle body with motor assembly connector.

    2. Disconnect the accelerator pedal sensor assembly connector.

    3. Disconnect the VVT sensor (for intake camshaft of bank 1) connector.

    4. Disconnect the VVT sensor (for intake camshaft of bank 2) connector.

    5. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C83-2 (VCTA) - Body ground and other terminals Always 10 kΩ or higher
      G145-6 (VCPA) - Body ground and other terminals Always 10 kΩ or higher
      G145-3 (VCP2) - Body ground and other terminals Always 10 kΩ or higher
      C85-12 (VCV1) - Body ground and other terminals Always 10 kΩ or higher
      C85-6 (VCV2) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR