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:
Using a flat bed truck
If you use chains or cables to tie down your vehicle, the angles shaded in black
must be 45°.
Do not overly tighten the tie downs or the vehicle may be damaged.
■Before emergency towing
1 Vehicles without a smart key system: Put the engine switch in the “ACC” (engine
off) or “O ...
Inspection procedure
1 Check ignition or starter switch assy
Check the ignition switch, as shown in the illustration and
table.
Standard:
2 Check fuse (ecu–b)
Remove the fuse from the instrument panel j/b.
check the continuity of the fuse.
Standard: continuity
3 Check relay (m ...
General information
There are many ecu controlled systems used in the corolla. In general, ecu
controlled system are considered
to be very intricate and require a high level of technical knowledge and expert
skill to troubleshoot.
The fact is, however, that if you proceed by inspecting the circuits one by one, ...


