VC Output Circuit

2UZ-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

Refer to the following pages.

- Throttle position sensor circuit P0120.
- Canister pump module circuit EVAP System.
- Secondary air injection pressure sensor circuit P0412.
- Camshaft position sensor circuit P0335.

INSPECTION PROCEDURE

PROCEDURE

1. CHECK MIL
(a) Check that the Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch ON.
OK:
MIL lights up
OK -- SYSTEM OK
NG -- Continue to next step.
2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and tester ON.
(c) Check the communication between the Techstream and ECM.
Result:






A -- GO TO MIL CIRCUIT
B -- Continue to next step.
3. INSPECT ECM
(a) Turn the ignition switch ON.





(b) Measure the voltage between E5-23 (VC) and E7-1 (E1) of the ECM connectors.
Standard voltage:
Voltage is not 5 V
NEXT -- Continue to next step.
4. CHECK MIL (THROTTLE POSITION SENSOR)
(a) Disconnect the T2 throttle body connector.
(b) Turn the ignition switch ON.
(c) Check the MIL.
Result:






A -- REPLACE THROTTLE BODY
B -- Continue to next step.
5. CHECK MIL (CAMSHAFT POSITION SENSOR)
(a) Disconnect the C1 camshaft position sensor connector.
(b) Turn the ignition switch ON.
(c) Check the MIL.
Result:






A -- REPLACE CAMSHAFT POSITION SENSOR
B -- Continue to next step.
6. CHECK MIL (CANISTER PUMP MODULE)
(a) Remove the spare tire.





(b) Disconnect the L4 canister pump module connector.
(c) Turn the ignition switch ON.
(d) Check the MIL.
Result:






A -- REPLACE CANISTER
B -- Continue to next step.
7. CHECK MIL (PRESSURE SENSOR)
(a) Remove the intake manifold Removal.
(b) Disconnect the A45 pressure sensor connector.
(c) Turn the ignition switch ON.
(d) Check the MIL.
Result:






A -- REPLACE AIR PRESSURE SENSOR
B -- Continue to next step.
8. CHECK HARNESS AND CONNECTOR
(a) Disconnect the T2 throttle body connector.
(b) Disconnect the C1 camshaft position sensor connector.
(c) Disconnect the L4 canister pump module connector.
(d) Disconnect the A45 pressure sensor.





(e) Disconnect the E5 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