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:
Steering wheel audio switches
Some audio features can be controlled using the switches on the steering wheel.
Operation may differ depending on the type of multimedia system or navigation
system. For details, refer to the manual provided with the multimedia system or
navigation system.
Operating the multimedia system using ...
Definition of terms
Term
Definition
Monitor description
Description of what the ecm monitors and how it detects malfunction
(monitoring purpose and its details).
Related dtcs
Diagnostic code
Typical enabling condition
Preconditions that allow the ecm to detect m ...
Circuit description
The rear heated oxygen sensor is used to monitor oxygen concentration in the
exhaust gas. For optimum
catalytic converter operation, the air fuel mixture must be maintained near the
ideal ”stoichiometric” ratio.
The heated oxygen sensor output voltage changes suddenly in the vicinity of ...


