A tricky fix for the ages
What is the most unusual problem you have ever run into? — Jack K.
The situation occurred many years ago when I was a shop foreman at a Pontiac dealership. We had just sold a gentleman a new Pontiac Bonneville that had buttons on the steering wheel to control the radio, CD tracks and so forth. This was prior to the advent of airbags, so the way the steering wheel buttons communicated with the steering column was via light- emitting diodes built into back of the steering wheel and photo-transistors embedded in the turn signal switch. Today’s airbag-equipped vehicles run circuits like this through the airbag clock spring to the stationary steering column.
The vehicle owner complained that the CD player would randomly change tracks in the middle of various songs. Try as I might, in four or five different repair attempts, I was never able to duplicate the complaint.
After exhausting all available service information and procedures, along with some wiggling and jiggling of connectors and adding a supplemental ground or two, I made contact with General Motor’s technical assistance hotline, and they suggested replacing various parts of the system, such as the steering wheel controller, the translator module, the turn signal switch, and even the radio and CD unit, none of which helped. The dealership’s supply of not- yet- sold vehicles out back allowed me to borrow and try the parts without needing to requisition or order them from the parts department. This method was officially frowned on but done quietly to get the customer’s car fixed as quickly as possible.
Finally, one late afternoon, I was driving the customer back to his home to drop him off so we could keep the car for another repair attempt. He had a long, estate- like driveway with towering trees along the sides. We were driving with the sunroof open, which I had never done before, and all of the sudden, the CD player began changing tracks. Then it hit me! The sunlight being interrupted by the trees was striking the top of the steering column. We drove back and forth several times up and down the driveway to duplicate the fault, and then I placed a shop towel over the crack between the steering wheel and steering column, and the problem completely went away. As it turns out, sunlight was getting into the area where the photo-transistors were, and the fleeting tree shadows were imitating the frequency of the steering wheel controller button for the CD channel track change.
I provided feedback to the Delco engineer I was working with, and his team produced a plastic guard to limit the amount of sunlight entering the crack. They also issued a service bulletin providing information for this fix, should it ever happen to anyone else.
Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at under- the- hood( at) earthlink. net; he cannot make personal replies.