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:
When stopping the engine with the shift lever in a position other than P (vehicles
with a continuously variable transmission)
If the engine is stopped with the shift lever in a position other than P, the
engine switch will not be turned off but instead be turned to ACCESSORY mode. Perform
the following procedure to turn the switch off:
1 Check that the parking brake is set.
2 Shift the shift lever to P.
► Vehi ...
Exhaust gas precautions
Harmful substance to the human body is included in exhaust gases if inhaled.
CAUTION
Exhaust gases include harmful carbon monoxide (CO), which is colorless and odorless.
Observe the following precautions.
Failure to do so may cause exhaust gases enter the vehicle and may lead to an
accident c ...
Malfunction in water temperature receiver gauge
Wiring diagram
Inspection procedure
1 Read value of hand–held tester
Check output value of ecm.
Connect the hand–held tester to dlc3.
Turn the ignition switch to on and push the hand–held tester main
switch on.
Select the data list mode on the hand–he ...


