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:
Timing gear cover oil seal
Replacement
1. Remove engine under cover rh
2. Remove front wheel rh
3. Remove fan and generator v belt
Turn the v–ribbed belt tensioner slowly clockwise and
loosen it. Then, remove the fan and generator belt v and
put back the v–ribbed belt tensioner little by little and fix
it ...
Shifting the shift lever
Vehicles without a smart key system:
While the engine switch is in the “ON” position, depress the brake pedal and
move the shift lever.
Vehicles with a smart key system: While the engine switch is in IGNITION ON mode,
depress the brake pedal and move the shift lever.
When shifting the ...
Circuit description
If the engine coolant temperature (ect) does not reach 75°c (167°f) despite
sufficient warm – up time has
elapsed.
Dtc no
Dtc detection condition
Trouble area
P0128
Condition (a), (b) and (c):
cold start
after engine is warmed up
& ...


