VC Output Circuit

4GR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: VC Output Circuit

VC Output Circuit

DESCRIPTION

The ECM constantly uses 5 V from the battery voltages 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 engine switch is first turned on (IG). The MIL goes off when the engine is started.

WIRING DIAGRAM









INSPECTION PROCEDURE

PROCEDURE

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






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





(d) Reconnect the throttle body connector.
A -- REPLACE THROTTLE BODY ASSEMBLY
B -- Continue to next step.
4. CHECK ACCELERATOR PEDAL ASSEMBLY (CHECK MIL ILLUMINATED)
(a) Disconnect the accelerator pedal position sensor connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the accelerator pedal position sensor connector.
A -- REPLACE ACCELERATOR PEDAL ASSEMBLY
B -- Continue to next step.
5. CHECK VVT SENSOR FOR INTAKE CAMSHAFT BANK 1 (CHECK MIL ILLUMINATED)
(a) Disconnect the VVT sensor for intake camshaft bank 1 connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the VVT sensor for intake camshaft bank 1 connector.
A -- REPLACE VVT SENSOR FOR INTAKE CAMSHAFT BANK 1
B -- Continue to next step.
6. CHECK VVT SENSOR FOR EXHAUST CAMSHAFT BANK 1 (CHECK MIL ILLUMINATED)
(a) Disconnect the VVT sensor for exhaust camshaft bank 1 connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the VVT sensor for exhaust camshaft bank 1 connector.
A -- REPLACE VVT SENSOR FOR EXHAUST CAMSHAFT BANK 1
B -- Continue to next step.
7. CHECK VVT SENSOR FOR INTAKE CAMSHAFT BANK 2 (CHECK MIL ILLUMINATED)
(a) Disconnect the VVT sensor for intake camshaft bank 2 connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the VVT sensor for intake camshaft bank 2 connector.
A -- REPLACE VVT SENSOR FOR INTAKE CAMSHAFT BANK 2
B -- Continue to next step.
8. CHECK VVT SENSOR FOR EXHAUST CAMSHAFT BANK 2 (CHECK MIL ILLUMINATED)
(a) Disconnect the VVT sensor for exhaust camshaft bank 2 connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the VVT sensor for exhaust camshaft bank 2 connector.
A -- REPLACE VVT SENSOR FOR EXHAUST CAMSHAFT BANK 2
B -- Continue to next step.
9. CHECK FUEL PRESSURE SENSOR (CHECK MIL ILLUMINATED)
(a) Disconnect the fuel pressure sensor connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





(d) Reconnect the fuel pressure sensor connector.
A -- REPLACE FUEL PRESSURE SENSOR
B -- Continue to next step.
10. CHECK CHARCOAL CANISTER ASSEMBLY (CHECK MIL ILLUMINATED)
(a) Disconnect the canister pump module connector.
(b) Turn the engine switch on (IG).
(c) Check the MIL.
Result:





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





(a) Disconnect the throttle body connector.
(b) Disconnect the accelerator pedal position sensor connector.
(c) Disconnect the VVT sensor for intake camshaft bank 1 connector.
(d) Disconnect the VVT sensor for exhaust camshaft bank 1 connector.
(e) Disconnect the VVT sensor for intake camshaft bank 2 connector.
(f) Disconnect the VVT sensor for exhaust camshaft bank 2 connector.
(g) Disconnect the fuel pressure sensor connector.
(h) Disconnect the canister pump module connector.
(i) Disconnect the E3, E5 and A6 ECM connectors.
(j) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for short):





(k) Reconnect the ECM connectors.
(l) Reconnect the canister pump module connector.
(m) Reconnect the fuel pressure sensor connector.
(n) Reconnect the VVT sensor for exhaust camshaft bank 2 connector.
(o) Reconnect the VVT sensor for intake camshaft bank 2 connector.
(p) Reconnect the VVT sensor for exhaust camshaft bank 1 connector.
(q) Reconnect the VVT sensor for intake camshaft bank 1 connector.
(r) Reconnect the accelerator pedal position sensor connector.
(s) Reconnect the throttle body connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM