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.

When the VC circuit has a short circuit, the microprocessor 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

• ECM Power Source Circuit

  Click here

• VC Output Circuit

*a	VCVG
*b	Mass Air Flow Meter
*c	Accelerator Pedal Sensor Assembly

CAUTION / NOTICE / HINT

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

      The Data List item "Engine and ECT" can be checked.

      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 (EFI NO. 3 FUSE)

   
   
   1. 

      *1	No. 1 Engine Room Relay Block
      *2	EFI NO. 3 FUSE

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

      Standard Voltage
      Tester Connection Condition Specified Condition 1 (EFI NO. 3 FUSE) - Body ground Always 11 to 14 V

      Tech Tips

      
      

      • Check that a EFI NO. 3 fuse is installed the relay block.

      • 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

   CHECK ECU POWER SOURCE CIRCUIT Click here

   OK

3. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (MANIFOLD ABSOLUTE PRESSURE SENSOR)

   
   

   1. Disconnect the C2 manifold absolute 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

      The Data List item "Engine and ECT" can be checked.

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

   
   

   B

   REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR Click here

   A

4. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (THROTTLE BODY ASSEMBLY)

   
   

   1. Disconnect the C4 throttle body 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

      The Data List item "Engine and ECT" can be checked.

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

      Tech Tips

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

      Click here

   
   

   B

   REPLACE THROTTLE BODY ASSEMBLY Click here

   A

5. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (CAMSHAFT POSITION SENSOR (FOR INTAKE CAMSHAFT))

   
   

   1. Disconnect the C19 camshaft position sensor (for intake camshaft) connector.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Check the communication between the GTS and ECM.

      Tech Tips

      The Data List item "Engine and ECT" can be checked.

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

   
   

   B

   REPLACE CAMSHAFT POSITION SENSOR (FOR INTAKE CAMSHAFT) Click here

   A

6. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (CAMSHAFT POSITION SENSOR (FOR EXHAUST CAMSHAFT))

   
   

   1. Disconnect the C41 camshaft position sensor (for exhaust camshaft) connector.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Check the communication between the GTS and ECM.

      Tech Tips

      The Data List item "Engine and ECT" can be checked.

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

   
   

   B

   REPLACE CAMSHAFT POSITION SENSOR (FOR EXHAUST CAMSHAFT) Click here

   A

7. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (OIL PRESSURE SENSOR)

   
   

   1. Disconnect the C44 oil 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

      The Data List item "Engine and ECT" can be checked.

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

   
   

   B

   REPLACE OIL PRESSURE SENSOR Click here

   A

8. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (MASS AIR FLOW METER)

   
   

   1. Disconnect the C5 mass air flow meter.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Check the communication between the GTS and ECM.

      Tech Tips

      The Data List item "Engine and ECT" can be checked.

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

      Tech Tips

      Perform "Inspection After Repair" after replacing the mass air flow meter.

      Click here

   
   

   B

   REPLACE MASS AIR FLOW METER Click here

   A

9. CHECK COMMUNICATION BETWEEN THE GTS AND ECM (ACCELERATOR PEDAL SENSOR ASSEMBLY)

   
   

   1. Disconnect the A46 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

      The Data List item "Engine and ECT" can be checked.

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

   
   

   B

   REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY Click here

   A

10. CHECK HARNESS AND CONNECTOR

    
    

    1. Disconnect the C2 manifold absolute pressure sensor connector.

    2. Disconnect the C4 throttle body with motor assembly connector.

    3. Disconnect the C19 camshaft position sensor (for intake camshaft) connector.

    4. Disconnect the C41 camshaft position sensor (for exhaust camshaft) connector.

    5. Disconnect the C44 oil pressure sensor connector.

    6. Disconnect the C5 mass air flow meter connector.

    7. Disconnect the A46 accelerator pedal sensor assembly connector.

    8. Disconnect the A38 and C62 ECM connectors.

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

       Standard Resistance

       Tester Connection Condition Specified Condition C63-77 (VCPM) - Body ground and other terminals Always 10 kΩ or higher C63-134 (VCTA) - Body ground and other terminals Always 10 kΩ or higher C63-116 (VCV1) - Body ground and other terminals Always 10 kΩ or higher C63-111 (VCE1) - Body ground and other terminals Always 10 kΩ or higher C63-110 (VCPT) - Body ground and other terminals Always 10 kΩ or higher C63-103 (VCVG) - Body ground and other terminals Always 10 kΩ or higher A38-49 (VCPA) - Body ground and other terminals Always 10 kΩ or higher 1 (EFI NO. 2 fuse holder) - A38-2(+B) Always Below 1 Ω 1 (EFI NO. 2 fuse holder) - A38-3(+B2) Always Below 1 Ω A38-2 (+B) - Body ground and other terminals Always 10 kΩ or higher A38-3 (+B2) - 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