VC Output Circuit

3UR-FE ENGINE CONTROL: SFI SYSTEM: VC Output Circuit
- VC Output Circuit

DESCRIPTION

The ECM constantly generates 5 V power 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 with 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) lights up when turning the ignition switch to ON.

OK:

MIL lights up

NG -- CHECK COMMUNICATION BETWEEN TECHSTREAM AND ECM

OK -- SYSTEM OK

2. CHECK COMMUNICATION BETWEEN TECHSTREAM AND ECM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and Techstream on.

(c) Check the communication between the Techstream and ECM.

Result





A -- GO TO MIL CIRCUIT MIL Circuit
B -- Continue to next step.

3. CHECK MIL (THROTTLE POSITION SENSOR)

(a) Disconnect the D4 throttle body connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE THROTTLE BODY ASSEMBLY Removal
B -- Continue to next step.

4. CHECK MIL (ACCELERATOR PEDAL POSITION SENSOR)

(a) Disconnect the A17 accelerator pedal position sensor connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE ACCELERATOR PEDAL POSITION SENSOR Removal
B -- Continue to next step.

5. CHECK MIL (CANISTER PUMP MODULE)

(a) Disconnect the O24 canister pump module connector.





(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE CHARCOAL CANISTER ASSEMBLY Removal
B -- Continue to next step.

6. CHECK MIL (AIR SWITCHING VALVE for Bank 1)

(a) Disconnect the D37 air switching valve connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE AIR SWITCHING VALVE Removal
B -- Continue to next step.

7. CHECK MIL (AIR SWITCHING VALVE for Bank 2)

(a) Disconnect the D38 air switching valve connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE AIR SWITCHING VALVE Removal
B -- Continue to next step.

8. CHECK MIL (POWER STEERING OIL PRESSURE SENSOR)

(a) Disconnect the D30 power steering oil pressure sensor connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE POWER STEERING OIL PRESSURE SENSOR
B -- Continue to next step.

9. CHECK MIL (CAMSHAFT POSITION SENSOR)

(a) Disconnect the D2 camshaft position sensor connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE CAMSHAFT POSITION SENSOR Removal
B -- Continue to next step.

10. CHECK MIL (CRANKSHAFT POSITION SENSOR)

(a) Disconnect the D1 crankshaft position sensor connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE CRANKSHAFT POSITION SENSOR Removal
B -- Continue to next step.

11. CHECK MIL (VVT SENSOR for Intake Side of Bank 1)

(a) Disconnect the D22 VVT sensor (for Intake Side of Bank 1) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE VVT SENSOR (for Intake Side of Bank 1) Removal
B -- Continue to next step.

12. CHECK MIL (VVT SENSOR for Exhaust Side of Bank 1)

(a) Disconnect the D24 VVT sensor (for Exhaust Side of Bank 1) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE VVT SENSOR (for Exhaust Side of Bank 1) Removal
B -- Continue to next step.

13. CHECK MIL (VVT SENSOR for Intake Side of Bank 2)

(a) Disconnect the D23 VVT sensor (for Intake Side of Bank 2) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE VVT SENSOR (for Intake Side of Bank 2) Removal
B -- Continue to next step.

14. CHECK MIL (VVT SENSOR for Exhaust Side of Bank 2)

(a) Disconnect the D25 VVT sensor (for Exhaust Side of Bank 2) connector.

(b) Turn the ignition switch to ON.

(c) Check the MIL.

Result





A -- REPLACE VVT SENSOR (for Exhaust Side of Bank 2) Removal
B -- Continue to next step.

15. CHECK HARNESS AND CONNECTOR

(a) Disconnect the D4 throttle body connector.

(b) Disconnect the A17 accelerator pedal position sensor connector.

(c) Disconnect the O24 canister pump module connector.

(d) Disconnect the D37 air switching valve connector.

(e) Disconnect the D38 air switching valve connector.

(f) Disconnect the D30 power steering oil pressure sensor connector.

(g) Disconnect the D2 camshaft position sensor connector.

(h) Disconnect the D1 crankshaft position sensor connector.

(i) Disconnect the D22 VVT sensor (for Intake Side of Bank 1) connector.

(j) Disconnect the D24 VVT sensor (for Exhaust Side of Bank 1) connector.

(k) Disconnect the D23 VVT sensor (for Intake Side of Bank 2) connector.

(l) Disconnect the D25 VVT sensor (for Exhaust Side of Bank 2) connector.

(m) Disconnect the A27 and D56 ECM connectors.





(n) 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