Home

Toyota Workshop

GSIC - Global Service Information Center

SFI SYSTEM (w/ EGR System) > VC Output Circuit

for Preparation Click here


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.

A207756E10

When the VC circuit is shorted, the microprocessor in the ECM and sensors that are supplied 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.

HINT:
Under normal conditions, the MIL is illuminated for several seconds when the power switch is first turned on (IG). The MIL goes off when the engine is started.


WIRING DIAGRAM


A221241E01


INSPECTION PROCEDURE

1.CHECK MIL

  1. Check that the Malfunction Indicator Lamp (MIL) illuminates when turning the power switch on (IG).

    OK:
    MIL lights up.



NG
Go to step 2
OK

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

2.CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM

  1. Connect the intelligent tester to the DLC3.

  1. Turn the power switch on (IG).

  1. Turn the tester on.

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

    Result:

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



A
GO TO MIL CIRCUIT (Click here)
B


3.CHECK MIL (THROTTLE POSITION SENSOR)

  1. Disconnect the throttle position sensor connector.

  1. Turn the power switch on (IG).

  1. Check the MIL.

    Result:

    Result
    		Proceed to
    MIL illuminates
    		A
    MIL does not illuminate
    		B

  1. Reconnect the throttle position sensor connector.



A
REPLACE THROTTLE BODY ASSEMBLY (Click here)
B


4.CHECK MIL (CAMSHAFT POSITION SENSOR)

  1. Disconnect the camshaft position sensor connector.

  1. Turn the power switch on (IG).

  1. Check the MIL.

    Result:

    Result
    		Proceed to
    MIL illuminates
    		A
    MIL does not illuminate
    		B

  1. Reconnect the camshaft position sensor connector.



A
REPLACE CAMSHAFT POSITION SENSOR (Click here)
B


5.CHECK MIL (MANIFOLD ABSOLUTE PRESSURE SENSOR)

  1. Disconnect the manifold absolute pressure sensor connector.

  1. Turn the power switch on (IG).

  1. Check the MIL.

    Result:

    Result
    		Proceed to
    MIL illuminates
    		A
    MIL does not illuminate
    		B

  1. Reconnect the manifold absolute pressure sensor connector.



A
REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR (Click here)
B


6.CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

  1. Disconnect the throttle position sensor connector.

  1. Disconnect the ECM connector.



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


    A194102E26


    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    D28-88 (VCTA) or D4-5 (VC) - Body ground
    		Always
    		10 kΩ or higher


    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Throttle Position Sensor)
    		*2
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the throttle position sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (THROTTLE POSITION SENSOR - ECM)
OK


7.CHECK HARNESS AND CONNECTOR (CAMSHAFT POSITION SENSOR - ECM)

  1. Disconnect the camshaft position sensor connector.

  1. Disconnect the ECM connector.



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


    A194109E44


    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    D18-3 (VC) or D28-99 (VCV1) - Body ground
    		Always
    		10 kΩ or higher


    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Camshaft Position Sensor)
    		*2
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the camshaft position sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (CAMSHAFT POSITION SENSOR - ECM)
OK


8.CHECK HARNESS AND CONNECTOR (MANIFOLD ABSOLUTE PRESSURE SENSOR - ECM)

  1. Disconnect the manifold absolute pressure sensor connector.

  1. Disconnect the ECM connector.



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


    A216384E03


    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    D3-3 (VC) or D28-72 (VCPM) - Body ground
    		Always
    		10 kΩ or higher


    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Manifold Absolute Pressure Sensor)
    		*2
    		Front view of wire harness connector
    (to ECM)

  1. Reconnect the manifold absolute pressure sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (MANIFOLD ABSOLUTE PRESSURE SENSOR - ECM)
OK

REPLACE ECM (Click here)