VC Output Circuit

3UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: VC Output Circuit
- VC Output Circuit

DESCRIPTION

The ECM constantly generates 5 V power from the battery voltage 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 are supplied power through the VC circuit are deactivated 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 ignition switch is first turned ON. The MIL goes off when the engine is started.

WIRING DIAGRAM





INSEPCTION PROCEDURE

PROCEDURE

1. CHECK MIL

(a) Check that the MIL lights up when turning the ignition switch to ON.

OK:

MIL lights up

NG -- CHECK CONNECTION BETWEEN TECHSTREAM AND ECM

OK -- END

2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and Techstream on.

(c) Check the communication between the Techstream and ECM.

Result:





B -- GO TO MIL CIRCUIT Testing and Inspection
A -- Continue to next step.

3. INSPECT ECM (VC VOLTAGE)





(a) Turn the ignition switch to ON.

(b) Measure the voltage of the ECM connector.

Standard Voltage:

Voltage is not 5.5 V

NEXT -- Continue to next step.

4. CHECK MIL (THROTTLE POSITION SENSOR)

(a) Disconnect the T26 throttle body connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result:





B -- REPLACE THROTTLE BODY ASSEMBLY Service and Repair
A -- Continue to next step.

5. CHECK MIL (CANISTER PUMP MODULE)

(a) Disconnect the C12 canister pump module connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result:





B -- REPLACE CANISTER
A -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)





(a) Disconnect the T26 throttle body connector.

(b) Disconnect the C12 canister pump module connector.

(c) Disconnect the E2 ECM connector.

(d) Measure the resistance of the wire harness connector.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Service and Repair