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:
Warning light and warning buzzer list
*1: Parking brake engaged warning buzzer:
*2: Open door warning buzzer:
*3: Vehicles with a drive monitor display
*4: Vehicles with a multi-information display
*5: Driver’s seat belt buzzer:
Vehicles without a smart key system: The driver’s seat belt buzzer sounds to alert
the d ...
Purpose of the readiness tests
The on–board diagnostic (obd ii) system is designed to monitor the
performance of emission–related
components and report any detected abnormalities in the form of diagnostic
trouble codes
(dtcs). Since the various components need to be monitored during different
driving condition ...
Circuit description
The actuator motor is operated by signals from the cruise control ecu assy.
Acceleration and deceleration
signals are transmitted by changes in the duty ratio (see below).
Duty ratio:
the duty ratio is the ratio of the period of continuity in one cycle. For
example, if a is the period of co ...


