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:
Inspection procedure
1 Inspect skid control ecu connector(+bs terminal voltage)
Disconnect the skid control ecu connector.
measure the voltage between terminals +bs (2) and gnd
(1, 23) of skid control ecu harness side connector.
Voltage: 10 – 14 v
2 Reconfirm dtc
Check the dtc .
Ok :
...
Inspection procedure
1 Check side squib(rh) circuit(airbag sensor assy center – front
seat airbag assy rh)
Disconnect the negative (–) terminal cable from the battery,
and wait at least for 90 seconds.
disconnect the connectors between the airbag sensor
assy center and the front seat airbag assy ...
Description
When troubleshooting obd ii vehicles, the only difference
from the usual troubleshooting procedure is that you
need to connect the vehicle to the obd ii scan tool complying
with sae j1978 or the hand–held tester, and read
various data output from the vehicle’s ecm.
Obd ii regulation ...


