VC Output Circuit

3MZ-FE ENGINE CONTROL SYSTEM: 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 (included in the hybrid vehicle control ECU) 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 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 power switch is first turned on (IG). The MIL goes off when the hybrid system is started.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK MIL CONDITION
(a) Check that the Malfunction Indicator Lamp (MIL) lights up when turning the power switch on (IG).
OK:
MIL lights up.
NG -- CHECK COMMUNICATION BETWEEN TECHSTREAM AND HYBRID VEHICLE CONTROL ECU
OK -- SYSTEM OK
2. CHECK COMMUNICATION BETWEEN TECHSTREAM AND HYBRID VEHICLE CONTROL ECU
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG) and turn the Techstream on.
(c) Check for communication between the Techstream and hybrid vehicle control ECU.
Result:






A -- GO TO MIL CIRCUIT
B -- Continue to next step.
3. CHECK MIL (THROTTLE POSITION SENSOR)
(a) Disconnect the throttle body connector.
(b) Turn the power 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 MIL (VAPOR PRESSURE SENSOR)
(a) Disconnect the fuel tank pressure sensor connector.
(b) Turn the power switch on (IG).
(c) Check the MIL.
Result:






A -- REPLACE VAPOR PRESSURE SENSOR ASSEMBLY
B -- Continue to next step.
5. CHECK MIL (CANISTER PUMP MODULE)





(a) Disconnect the canister pump module connector.
(b) Turn the power 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.
6. CHECK HARNESS AND CONNECTOR





(a) Disconnect the throttle body connector.
(b) Disconnect the fuel tank pressure sensor connector.
(c) Disconnect the canister pump module connector.
(d) Disconnect the hybrid vehicle control ECU connector.
(e) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for short):





(f) Reconnect the throttle body connector.
(g) Reconnect the fuel tank pressure sensor connector.
(h) Reconnect the canister pump module connector.
(i) Reconnect the hybrid vehicle control ECU connectors.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE HYBRID VEHICLE CONTROL ECU