VC Output Circuit

1GR-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 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 ignition switch is first turned ON. The MIL goes off when the engine is started.

WIRING DIAGRAM









INSPECTION PROCEDURE

PROCEDURE

1. CHECK MIL

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

OK:

MIL lights up

NG -- CHECK CONNECTION BETWEEN TECHSTREAM AND ECM

OK -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and turn the 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. CHECK MIL (THROTTLE WITH MOTOR BODY ASSEMBLY)

(a) Disconnect the throttle with motor body connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE THROTTLE WITH MOTOR BODY ASSEMBLY Removal
A -- Continue to next step.

4. CHECK MIL (ACCELERATOR PEDAL)

(a) Disconnect the accelerator pedal connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE ACCELERATOR PEDAL ASSEMBLY Removal
A -- Continue to next step.

5. CHECK MIL (CANISTER PUMP MODULE)

(a) Disconnect the canister pump module connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





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

6. CHECK MIL (VVT SENSOR FOR INTAKE SIDE OF BANK 1)

(a) Disconnect the VVT sensor (for Intake Side of Bank 1) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE VVT SENSOR (FOR INTAKE SIDE OF BANK 1) Removal
A -- Continue to next step.

7. CHECK MIL (VVT SENSOR FOR EXHAUST SIDE OF BANK 1)

(a) Disconnect the VVT sensor (for Exhaust Side of Bank 1) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE VVT SENSOR (FOR EXHAUST SIDE OF BANK 1) Removal
A -- Continue to next step.

8. CHECK MIL (VVT SENSOR FOR INTAKE SIDE OF BANK 2)

(a) Disconnect the VVT sensor (for Intake Side of Bank 2) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE VVT SENSOR (FOR INTAKE SIDE OF BANK 2) Removal
A -- Continue to next step.

9. CHECK MIL (VVT SENSOR FOR EXHAUST SIDE OF BANK 2)

(a) Disconnect the VVT sensor (for Exhaust Side of Bank 2) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE VVT SENSOR (FOR EXHAUST SIDE OF BANK 2) Removal
A -- Continue to next step.

10. CHECK MIL (POWER STEERING OIL PRESSURE SWITCH)

(a) Disconnect the power steering oil pressure switch connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





B -- REPLACE POWER STEERING OIL PRESSURE SWITCH Removal
A -- Continue to next step.

11. CHECK HARNESS AND CONNECTOR

(a) Disconnect the throttle with motor body assembly connector.

(b) Disconnect the accelerator pedal connector.

(c) Disconnect the canister pump module connector.

(d) Disconnect the VVT sensor (for Intake Side Bank 1) connector.

(e) Disconnect the VVT sensor (for Exhaust Side Bank 1) connector.

(f) Disconnect the VVT sensor (for Intake Side Bank 2) connector.

(g) Disconnect the VVT sensor (for Exhaust Side Bank 2) connector.

(h) Disconnect the power steering oil pressure switch connector.

(i) Disconnect the ECM connector.

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

Standard Resistance (Check for Short):





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal