Automatic Climate Control II

CAUTION: Before carrying out any work on the system, the 25 pin connector on the ACC control module must be unplugged. The control module may be damaged if it is exposed to certain voltages.

Fault Diagnosis, ACC
There is a fault diagnosis and monitoring program built in to the ACC system control module. Certain features are continuously monitored while driving, but others must be check manually.
The following features are monitored while driving:
^ interior air sensor
^ outside temperature sensor
^ blended air sensor
If there is a fault in any of the sensors, an emergency program is engaged. The fault can then be searched for using a manual self test.

The following features are not monitored during driving:
^ electric motors for temperature valve
^ air distribution
^ recirculation and fan motor and fan control
^ solar sensor


Manual Fault Diagnosis
During fault diagnosis, the ACC control module runs a program. The display then shows the number of faults and gives a diagnostic trouble code for each fault.
The following types of fault are indicated:
^ open circuit
^ short circuit
^ component fault
^ motor blockage
^ incorrect direction of rotation (electric motor)

However, there is no indication as to whether the fault is in the component or the wiring (for example in the case of faults which involve open circuit or short circuit).

For example: Diagnostic trouble code indicates open circuit in outside temperature sensor (2U). This means that connectors, wiring and the sensor must be checked to see if there is voltage to the outside temperature sensor. If there is voltage, try with a new sensor. If the fault remains, try using a new ACC control module.





Manual Fault Diagnosis Is Conducted As Follows
Press AUTO and VENT at the same time. Release the buttons.

The ACC control module then runs through a fault diagnosis program (about 40 seconds) which is indicated by 88 flashing on the display. After fault diagnosis, the number of faults can be read on the display. Press VENT once and the first diagnostic trouble code is displayed. Press once again for the next diagnostic trouble code etc.

Return to normal program by pressing AUTO.





Other Fault Diagnosis