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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    Road test
    1. Problem symptom confirmation Taking into consideration the results of the customer problem analysis, try to reproduce the symptoms of the trouble. If the problem is that the transaxle does not shift up, shift down, or the shift point is too high or too low conduct the following road ...

    Initialization
    1. Reset memory Caution: perform the reset memory (at initialization) when replacing the automatic transaxle assy, engine assy or ecm. Notice: hand–held tester only Turn the ignition switch off.  connect the hand–held tester to the dlc3.  turn the ignition switch to th ...

    For vehicles equipped with mobile communication system
    Install an antenna as far as possible away from the ecu and sensors of the vehicle’s electronic systems.  install an antenna feeder at least 20 cm (7.87 In.) Away from the ecu and sensors of the vehicle’s electronic systems. For details of the ecu and sensors locations, refer ...