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:
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
Refer to dtc p0120
Dtc no.
Dtc detection condition
Trouble area
P0121
The following condition is met 4 times. After the vehicle speed
has exceeded 19 mph (30 km/h) once, the throttle position
sensor output value is out of normal range when the throttle
...
Vehicle information
This screen can be used to display the fuel consumption.
“Trip Information” or “Past Record” screen
Press “CAR” to display the “Trip Information” or “Past Record” screen.
Fuel consumption
■ Trip information
If the “Trip Information” screen does not appear, select ...


