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


















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 turn the tester ON.
(c) Check the communication between the Techstream and ECM.





A -- GO TO MIL CIRCUIT
B -- Continue to next step.
3. CHECK MIL (THROTTLE BODY)
(a) Disconnect the throttle body connector.
(b) Turn the ignition switch ON.
(c) Check the MIL.
Result:





A -- REPLACE THROTTLE BODY
B -- Continue to next step.
4. CHECK MIL (ACCELERATOR PEDAL)
(a) Disconnect the accelerator pedal connector.
(b) Turn the ignition switch ON.
(c) Check the MIL.
Result:





A -- REPLACE ACCELERATOR PEDAL ASSEMBLY
B -- Continue to next step.
5. CHECK MIL (PRESSURE SENSOR FOR SECONDARY AIR INJECTION)
(a) Disconnect the pressure sensor connector.
(b) Turn the ignition switch ON.
(c) Check the MIL.
Result:





A -- REPLACE 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 ON.
(c) Check the MIL.
Result:





A -- REPLACE CHARCOAL CANISTER ASSEMBLY
B -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR
(a) Disconnect the throttle body connector.
(b) Disconnect the accelerator pedal connector.
(c) Disconnect the 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