Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Mil circuit / Circuit description
Toyota Corolla (E120): Circuit description
The ignition switch provides circuit power and the ecm provides the circuit ground that illuminates the mil.
Mil operation is checked visually: it should be illuminated when the ignition is first turned on. If the mil is off all of the time or on all of the time, use the procedure below to troubleshoot it. The mil is used to indicate the ecm’s detection of a vehicle malfunction.
Follow this procedure using the hand–held tester or an obd ii scan tool to determine the cause of the problem and to check the mil.
Wiring diagram

Other materials:
About this vehicle
1. Structural outline
2. Notice about vehicle condition when jacking up
vehicle
(a) notice for using jack and safety stand
(B) notice for using swing arm type lift
(C) notice for using plate type lift
3. Damage diagnosis
4. Components
(a) front bumper
(B) side mu ...
Monitor description
Dtc p0451, p0452 or p0453 is recorded by the ecm when the vapor pressure
sensor malfunctions.
P0451
The ecm senses pressure in the fuel tank using the vapor pressure sensor. The
ecm supplies the sensor
with a regulated 5 v reference–voltage and the sensor returns a signal voltage
betwee ...
Evap monitor (vacuum pressure monitor)
Notice:
a cold soak must be performed prior to conducting the drive pattern to complete
the internal pressure
readiness monitor.
Cold soak preconditions
The monitor will not run unless:
mil is off.
Fuel level is approximately 1/2 to 3/4.
Altitude is 7800 feet (2400 m) or less.
...


