VC Output Circuit

2TR-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 to ON. The MIL goes off when the engine is started.

WIRING DIAGRAM

Refer to the following pages.

* Throttle position sensor circuit P0120.

* Canister pump module circuit P0451.

* Secondary air injection pressure sensor circuit P2431.

* Accelerator pedal circuit P2120.

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

OK -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
NG -- Continue to next step.

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





A -- GO TO MIL CIRCUIT MIL Circuit
B -- Continue to next step.

3. CHECK MIL (THROTTLE BODY ASSEMBLY)

(a) Disconnect the throttle body assembly connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





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

4. CHECK MIL (ACCELERATOR PEDAL SENSOR ASSEMBLY)

(a) Disconnect the accelerator pedal sensor assembly connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





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

5. CHECK MIL (AIR PRESSURE SENSOR FOR SECONDARY AIR INJECTION)

(a) Disconnect the air pressure sensor connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE AIR PRESSURE SENSOR
B -- Continue to next step.

6. CHECK MIL (CANISTER PUMP MODULE)

(a) Disconnect the canister pump module connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE CANISTER PUMP MODULE Removal
B -- Continue to next step.

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

(a) Disconnect the throttle body assembly connector.

(b) Disconnect the accelerator pedal sensor assembly connector.

(c) Disconnect the air pressure sensor connector.

(d) Disconnect the canister pump module connector.

(e) Disconnect the ECM connector.





(f) Measure the resistance of the wire harness side connector.

Standard Resistance (Check for Short):





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal