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:
Overhaul
1. Remove bench type rear seat cushion assy
Disengage the 2 clamps, and then remove the seat cushion.
2. Remove separate type rear seat back assy
lean the seat back forward.
remove the 2 clips.
remove the 2 bolts and seat back lh.
employ the same manner describ ...
Engine assembly
Inspection
1. Inspect coolant
2. Inspect engine oil
3. Inspect battery
4. Inspect air cleaner filter element sub–assy
5. Inspect spark plug
6. Inspect fan and generator v belt
Hint:
you don’t need to check the belt deflection because auto tensioner is adopted.
7. Inspect ignition ti ...
Circuit description
A thermistor is built in the engine coolant temperature sensor and changes
the resistance value according
to the engine coolant temperature.
The structure of the sensor and connection to the ecm is the same as those of
the intake air temperature
sensor.
Hint:
if the ecm detects the dtc ...


