Toyota 2GR-FE Manual page 606

ES–450
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 ignition switch is first turned
on (IG). The MIL goes off when the engine is started.
ES
Throttle Position Sensor, Accelerator
Pedal Position Sensor, etc. (Sensors
which have IC)
Engine Coolant Temperature Sensor,
Intake Air Temperature Sensor, etc.
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
BATT
From EFI MAIN Fuse
From EFI Relay
5 V Constant Voltage Circuit
+B
VC
R
ECM
Microprocessor
A116143E14