Toyota Corolla (E120): Circuit description

When the ignition switch is turned on, battery positive voltage is applied to the coilwhich closes the contacts of the efi main relay (marked: efi) and supplies power to terminal +b of the ecm.

This signal causes current to flow to the coil, closing the contacts of the efi relay and supplying power to terminal +b of the ecm.

If the ignition switch is turned off, the ecm continues to switch on the efi relay for a maximum of 2 seconds for the initial setting of the isc valve.

Wiring diagram

Inspection procedure

    Share this page:

    Other materials:

    Inspection procedure
    1 Inspect park/neutral position switch assy Disconnect the park/neutral position switch connector.  measure resistance according to the value(s) in the table below when the shift lever is moved to each position. Standard: 2 Check harness and connector(park/neutral position ...

    Inspection procedure
    1 Check p/t squib(rh) circuit(airbag sensor assy center – front seat outer belt 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 seat belt pretensio ...

    General information
    There are many ecu controlled systems used in the corolla. In general, ecu controlled system are considered to be very intricate and require a high level of technical knowledge and expert skill to troubleshoot. The fact is, however, that if you proceed by inspecting the circuits one by one, ...