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) illuminates when turning the ignition switch to ON.
OK:
MIL illuminates.
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.
(c) Turn the Techstream on.
(d) Check the communication between the Techstream and ECM.
Result
B -- GO TO MIL CIRCUIT MIL Circuit
A -- Continue to next step.
3. CHECK MIL (THROTTLE POSITION SENSOR)
(a) Disconnect the throttle with motor body assembly 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 POSITION SENSOR)
(a) Disconnect the accelerator pedal rod assembly connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.
Result
B -- REPLACE ACCELERATOR PEDAL ROD 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 PUMP MODULE Removal
A -- Continue to next step.
6. CHECK MIL (VVT SENSOR (BANK 1))
(a) Disconnect the VVT sensor (bank 1) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.
Result
B -- REPLACE VVT SENSOR (BANK 1) Removal
A -- Continue to next step.
7. CHECK MIL (VVT SENSOR (BANK 2))
(a) Disconnect the VVT sensor (bank 2) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.
Result
B -- CHECK HARNESS AND CONNECTOR
C -- REPLACE VVT SENSOR (BANK 2) Removal
A -- Continue to next step.
8. CHECK MIL (AIR SWITCHING VALVE (BANK 1))
(a) Disconnect the air switching valve (bank 1) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.
Result
B -- REPLACE AIR SWITCHING VALVE ASSEMBLY Removal
A -- Continue to next step.
9. CHECK MIL (AIR SWITCHING VALVE (BANK 2))
(a) Disconnect the air switching valve (bank 2) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.
Result
B -- REPLACE AIR SWITCHING VALVE ASSEMBLY Removal
A -- Continue to next step.
10. CHECK HARNESS AND CONNECTOR
(a) Disconnect the throttle with motor body assembly connector.
(b) Disconnect the accelerator pedal rod assembly connector.
(c) Disconnect the canister pump module connector.
(d) Disconnect the VVT sensor (bank 1) connector.
(e) Disconnect the VVT sensor (bank 2) connector.
(f) Disconnect the air switching valve (bank 1) connector (w/ secondary air injection system).
(g) Disconnect the air switching valve (bank 2) connector (w/ secondary air injection system).
(h) Disconnect the ECM connector.
(i) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM Removal