Toyota Corolla (E120): Check and replace ecu
Notice
: start an inspection of the connector from the backside of the connector on the wire harness side with the connector connected to the ecu.
When no measurement condition is specified, perform the inspection with the engine stopped and also the ignition switch on.
- First check the ecu ground circuit. If it is faulty, repair it.
If it is normal, the ecu could be faulty. In this case, replace the ecu with one that functions normally and check if the symptoms appear.
- Measure the resistance between the ecu ground
terminal and body ground.
Resistance: 1 Ω or less

- Disconnect the ecu connector, check the ground terminals on the ecu side and wire harness side for bends and check the contact pressure.

Other materials:
Engine immobilizer system
The vehicle’s keys have built-in transponder chips that prevent the engine
from starting if a key has not been previously registered in the vehicle’s on-board
computer.
Never leave the keys inside the vehicle when you leave the vehicle.
Vehicles without a smart key system: The indicator li ...
Circuit description
When the brake pedal is depressed, the stop lamp switch assy sends a signal
to the cruise control ecu assy.
When the cruise control ecu assy receives this signal, it cancels the cruise
control.
A fail–safe function is provided so that cancel functions normally, even if
there is a malfu ...
Diagnostic trouble code chart
If a dtc is displayed during the dtc check, check the circuit listed in the
table below and proceed to the
page given.
* :● ... Mil light up
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