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

Refer to the following.

- Throttle position sensor circuit.






- Canister pump module circuit.






- Accelerator pedal circuit.






- VVT sensor circuit.






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
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
A -- Continue to next step.

3. CHECK MIL (THROTTLE BODY)
(a) Disconnect the throttle body connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.

Result





(d) Reconnect the throttle body connector.
B -- REPLACE THROTTLE BODY ASSEMBLY
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





(d) Reconnect the accelerator pedal connector.
B -- REPLACE ACCELERATOR PEDAL ASSEMBLY
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





(d) Reconnect the canister pump module connector.
B -- REPLACE CHARCOAL CANISTER ASSEMBLY
A -- Continue to next step.

6. CHECK MIL (VVT SENSOR FOR BANK1)
(a) Disconnect the VVT sensor (bank 1) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.

Result





(d) Reconnect the VVT sensor (bank 1) connector.
B -- REPLACE VVT SENSOR (BANK 1)
A -- Continue to next step.

7. CHECK MIL (VVT SENSOR FOR BANK2)
(a) Disconnect the VVT sensor (bank 2) connector.
(b) Turn the ignition switch to ON.
(c) Check the MIL.

Result





(d) Reconnect the VVT sensor (bank 2) connector.
B -- REPLACE VVT SENSOR (BANK 2)
A -- Continue to next step.

8. CHECK HARNESS AND CONNECTOR
(a) Disconnect the throttle body connector.
(b) Disconnect the accelerator pedal 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 ECM connector.
(g) Measure the resistance according to the value(s) in the table below.
Standard Resistance (check for short):





(h) Reconnect the throttle body connector.
(i) Reconnect the accelerator pedal connector.
(j) Reconnect the canister pump module connector.
(k) Reconnect the VVT sensor (bank 1) connector.
(l) Reconnect the VVT sensor (bank 2) connector.
(m) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM