Toyota Corolla (E120): Circuit description

The key unlock warning switch comes on when the ignition key is inserted in the key cylinder and goes off when the ignition key is removed.

Wiring diagram

Inspection procedure

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    Circuit description
    The rear heated oxygen sensor is used to monitor oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air fuel mixture must be maintained near the ideal ”stoichiometric” ratio. The heated oxygen sensor output voltage changes suddenly in the vicinity of ...

    Inspection procedure
    Hint: read freeze frame data using the hand-held tester or the obd ii scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the ...

    Coolant
    Replacement 1. Drain coolant Caution: to avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot, as fluid and steam can be blown out under pressure.  remove the radiator cap.  loosen the radiator and engine drain plugs, a ...