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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    Inspection procedure
    1 Check front airbag sensor (lh) circuit (to b+)(airbag sensor assy center – airbag sensor front lh) 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 airbag ...

    Precaution
    Caution: replace the faulty parts of the seat belt systems (outer belt, inner belt, bolts, nuts, adjustable shoulder anchor, tether anchor hardware, sill–bar, etc.). Seat belt systems not in use at the time of a collision should also be inspected and replaced if found to be damaged or wo ...

    Monitor description
    The battery supplies electricity to the ecm even when the ignition switch is off. This electricity allows the ecm store data such as dtc history, freeze frame data, fuel trim values, and other data. If the battery voltage falls below a minimum level, the ecm will conclude that there is a fault ...