WWW.CARDIAGNOSTICS.BE IS SUPER !! Self Diagnose Toyota Corolla ECC-panel

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General information

AC control module incorporates self-diagnosis function.

AC control module trouble codes can be displayed on the control panel.


Accessing trouble codes

Ensure ignition switched OFF.

Depress and hold 'AUTO' switch [1].

Depress and hold 'recirculation/fresh air' switch [2].

Switch ignition ON.

AC/heater control panel LED's [3] and LCD [4] should illuminate 4 times.

System is now in diagnostic check mode.

Trouble codes are displayed by AC temperature/outside temperature display.

For example: Trouble code 21 displayed [5].


To display trouble codes individually:

Depress front defrost switch [6].

Depress front defrost switch [6] again to move to next trouble code.

Note trouble codes. Compare with trouble code table.

Switch ignition OFF. Rectify faults as necessary.


Erasing trouble codes

Ensure system in diagnostic check mode.

Depress and hold front defrost switch [6] and heated rear window switch [7] simultaneously.

Trouble codes erased.

Switch ignition OFF.

The AC control module fault memory can also be erased by removing fuse F10 (15A) from the engine bay fuse box for 20 seconds minimum.

Refit fuse.


Trouble code identification:


00     No fault found

11     In-car temperature sensor

12     Outside air temperature sensor

13     AC evaporator temperature sensor

14     Engine coolant temperature (ECT) sensor

21     AC sunlight sensor

22     AC compressor clutch lock sensor

23     AC refrigerant triple pressure switch

31     AC/heater air mix flap motor, potentiometer

33     AC/heater air direction motor, potentiometer

41     AC/heater air mix flap motor

43     AC/heater air direction motor





 Here is a real money-saving tip for you Toyota owners, with a problem of your AC light flashing on the instrument panel, when the AC is on.

You may also expericence a 'no cooling condition', also.

This info pertains to the following Toyota vehicles:

2001 thru 2004 Camry, Echo and Celica

2002 thru 2004 4Runner, Corolla, MR2 Spyder

2003 thru 2004 Highlander, Matrix, Sienna and Solara

Toyota is aware of this situation, and has produced a technical service bulletin to rectify the AC light flashing condition.

What has happened here is that the AC relay (noted as the 'AC MG CLUTCH or CLT'  white relay in the relay box, under the hood) has gotten weak over time, and is not properlying transmitting power to engage the AC compressor clutch.

Toyota has an improved relay available, and can be purchased at any Toyota parts department.

The affected relays have the following part number stamped on them: 90987-02022

The improved relay part number is 90987-02028

The repair is quite easy, all you have to do is identify that you have a 90987-02022 relay. If so, purchase a new relay, 90987-02028, and simply remove the old one, and fit the new one into the relay box.

Once the new relay is installed, the AC light flashing problem will be cured.

We hope that this tip saves you the money that you would have paid a repair facility to daignose the problem for you.


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