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

Inspection procedure

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    Problem symptoms table
    The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to troubleshoot the problem when a normal code is displayed in the diagnostic trouble code chart but the problem is still occurring. Numbers in the table indicate the order in which the circ ...

    Inspection procedure
    1 Check d squib circuit(airbag sensor assy center – horn button assy) Disconnect the negative (–) terminal cable from the battery, and wait at least for 90 seconds.  disconnect the connectors between the horn button assy and the airbag sensor assy center.  for the oran ...