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:
Circuit description
Refer to dtc p0115
Dtc no.
Dtc detection condition
Trouble area
P0125
If the engine coolant temperature (ect) was less than –6.6 °C
(20 °F) when starting the engine, and 20 minutes after the engine
start, the ect sensor still indicates below 20 °C (68 ...
Using the rear view monitor system
■ Screen description
1 Vehicle width guide lines
The line indicates a guide path when the vehicle is being backed straight up.
The displayed width is wider than the actual vehicle width.
2 Vehicle center guide lines
These lines indicate the estimated vehicle center on the ground.
3 Dis ...
Emission inspection and maintenance (I/M) programs
Some states have vehicle
emission inspection programs
which include OBD
(On Board Diagnostics)
checks. The OBD system
monitors the operation of
the emission control system.
If the malfunction indicator
lamp comes on
The OBD system determines
that a problem exists somewhere
in the emission control
sy ...


