SFI SYSTEM VC Output Circuit

DESCRIPTION

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

B001H4RE48

When the VC circuit is short-circuited, the microprocessor in the ECM and the sensors that are supplied with power through the VC circuit are inactivated because 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

B001FUQE04

PROCEDURE


  1. READ VALUE USING GTS


    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

    A

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ECM)

    B001FBBE02
    Text in Illustration
    *a

    Component with harness connected

    (ECM)

    1. 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
      G180-1(+B) - Body ground Ignition switch ON 11 to 14 V
      G180-2(+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 MIL CIRCUIT Click here

    OK

  3. CHECK CONNECTION BETWEEN GTS AND ECM (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 cleaning the throttle body Click here.


    B

    REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY Click here

    A

  4. CHECK CONNECTION BETWEEN GTS AND ECM (ACCELERATOR PEDAL POSITION SENSOR)


    1. Disconnect the accelerator pedal position sensor 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 CONNECTION BETWEEN GTS AND ECM (AIR PRESSURE SENSOR)


    1. Disconnect the air pressure sensor 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 AIR PRESSURE SENSOR Click here

    A

  6. CHECK CONNECTION BETWEEN GTS AND ECM (MASS AIR FLOW METER SUB-ASSEMBLY)


    1. Disconnect the mass air flow meter sub-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 MASS AIR FLOW METER SUB-ASSEMBLY

    A

  7. CHECK CONNECTION BETWEEN GTS AND ECM (CAMSHAFT POSITION SENSOR (FOR INTAKE SIDE))


    1. Disconnect the camshaft position sensor (for intake side) 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 CAMSHAFT POSITION SENSOR (FOR INTAKE SIDE) Click here

    A

  8. CHECK CONNECTION BETWEEN GTS AND ECM (CAMSHAFT POSITION SENSOR (FOR EXHAUST SIDE))


    1. Disconnect the camshaft position sensor (for exhaust side) 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 CAMSHAFT POSITION SENSOR (FOR EXHAUST SIDE) Click here

    A

  9. CHECK HARNESS AND CONNECTOR


    1. Disconnect the throttle body with motor assembly connector.

    2. Disconnect the accelerator pedal sensor assembly connector.

    3. Disconnect the air pressure sensor connector (with air pressure sensor).

    4. Disconnect the mass air flow meter sub-assembly connector.

    5. Disconnect the camshaft position sensor (for intake side) connector.

    6. Disconnect the camshaft position sensor (for exhaust side) 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
      C153-29 (VCTA) - Body ground Always 10 kΩ or higher
      G180-20 (VCPA) - Body ground Always 10 kΩ or higher
      G180-22 (VCP2) - Body ground Always 10 kΩ or higher
      C153-20 (VCAI) - Body ground Always 10 kΩ or higher
      C153-31 (VCE1) - Body ground Always 10 kΩ or higher
      C153-21 (VCV1) - Body ground Always 10 kΩ or higher

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR