AL4 Multifunction Switch Fault


Document created: 22.03.2003
Last updaded: --.--.----

Model:

All models equipped with an AL4 automatic transmission

Symptoms:

Warning lights flashing. (Snow and sport light flashing simultaneously) this is usually accompanied with shift quality related complaints.

Fault codes:

The following fault codes can be stored in the ECU.

  1. Automatic transmission control unit. Permanent (intermittent) fault. Multifunction switch open/short circuit.


  2. Automatic transmission control unit. Permanent (intermittent) fault. Multifunction switch intermediate position

Possible Causes:

  1. Defectiv Switch
  2. Switch out of adjustment
  3. Poor connection

Rectification:

A permanent fault usually indicates that the switch is defective and fitting a new part will solve the problem.

With an intermittent fault it may be possible that the switch is out of adjustment. The fault can be induced by slowly moving the lever between speeds. With D selected and light pressure applied towards 3 observe the selector indicator on the instruments. If the light at D goes off followed by the warning lights flashing, this means the fault has been triggered. Another way to do this is by moving the selector lever slowly from 3 towards D. This is much more difficult to do. Easy inducement by manipulating the selector lever means, there is a high probability of an incorrect switch adjustment. Adjusting the switch should solve the problem.

Should all of the above fail to permanently solve the problem, it will be necessary to do some wiring and connection checking. We like to save this time consuming and tedious task as a last resort. In our experience the most encountered problems are switch defects and adjustments.

Contacts

We opened up a multifunction switch in order to find out what goes wrong. The picture above shows a contact slider with the broken contact tips clearly visible. It appears that the material becomes brittle possibly due to thermal stress. The temperatures on top of the transmission can be quite high and put a high demand on material quality.


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