I have had this problem for the past three years and have only recently even figured out a possible cause. The operation of the audio and cruise control buttons on the steering wheel periodically is not correct. The vol- actually becomes vol+, vol+ become preset+, unable to cancel cruise, etc. Due to the subtle application of the instrument panel lights, which includes the lighted buttons on the steering wheel, I was not able to easily correlate the occurrence of this behavior with other things that were going. It recently got the best of me and I have spent too much time pulling off the steering wheel, taking apart the clockspring connector, digging down to the ECU to look for water damage, etc. I finally figured out that the behavior is associated with use of the instrument panel dimmer at settings greater then 1/3 of the dimmer knob rotation, and only when the dimmer is in use.

Has anyone observed this? Any clues as to where I should go next to troubleshoot this problem?

 

My first wild-a-guess would be to swap the stalk with another unit. That thing has been problematic in other models (like the xk8-r), but I haven't ever seen an incident that ties it to the dimmer switch...so very far away from the steering wheel. That baffles me. Looks like its process of elimination, and hope its not ultimately the instrument panel itself...that'd be painful.

 

The steering wheel circuits check out fine, but I am unable to measure them while the dimmer is on. I don't expect it is the resistors because two separate packs (audio controls and cruise controls) would be misbehaving the same way related to the the dimmer setting. I'm thinking it could be a ground issue or something, but I am searching for clues as to where I should start looking. The only thing that is common between the two packs in the wiring diagram is that they use a common ground line starting in the wheel and going through the ECU. But what does the dimmer have anything to do with that?