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Why do my son's Pontiac G6 wipers go on when hitting the turn signal?

My son has a 2005 Pontiac G6 with around 100,00 miles on it. Recently, when he is driving and hits the turn signal, the wipers go on… and stay on. He tries to get them to stop using the wiper controls, but nothing happens. At some point (several minutes to an hour or two) they stop. Nothing will occur for a while, but out of the blue, when signalling a turn, they start in again. Also, when they are on, the horn won’t work. I’m telling him that the car is haunted. Any other ideas?

worn out multi-function switch.
All those switches are down in there together and this age of vehicle will do those things.

I agree with a faulty multi-function switch, but it normally should last more than 7 years. The one in my '88 Toyota has lasted 25 years so far. My Ford, 12 years.

Since the turn signal switch and the wiper switch are on different stalks, it could be one or the other or a short in the wire inside the steering wheel. Just going to have to have the steering wheel taken off and investigate the wiring inside.

Initially, the answer from the GM Dealer was to replace the multi-function switch. But later I stopped at an independent repair shop and was told what you said Bing, the controls are on two separate switches. They told me that I may need to replace the control module. I don’t like the idea of spending $200 on replacing the multi-function switch only to find out that I still have the problem and now am looking at a $370 replacement of the control module. So, based on the symptoms, is the GM Dealership correct or my independent mechanic?

The problem could be with the Body Control Module. Both circuits pass thru the BCM. And each circuit has its own independent switch.

Tester

I dropped it off at my mechanic to try and figure out. Of course, it wouldn’t replicate the behavior while there. Later I talked to my son again who said, “Oh yea, when the lights are turned off, I don’t have a problem controlling the wiper.” So, it appears that it is triggered by the turn signal, doesn’t act up when the auto on headlights are turned off, and the wipers are on a separate circuit.

I just repaired my neighbors 2003 Kia Sedona with a similar problem. The turn signals and wipers are on different stalks but they mount to a common component. Her wipers would not go off except for turn signal operations. When the turn signal returned to normal…the wipers came back on.

The problem was a broken wire in the wiper control. Repaired the wire and she is now a happy camper. BTW…this common component must be replaced if the cruise control, wipers or turn signals have problems. It has a hefty price. Bad engineering in my opinion.

I had the same problem - check the three grounds by your battery on the radiator support first - take off the 10mm nut and clean the cable and the metal off. Mine was a bad ground, I believe it is the one closest to the fender as that runs the turn signals and the wiper. In any event, I cleaned all those and it has worked perfectly ever since. My guess is if the ground is bad, the power back feeds into the wiper circuit. It only takes 10 minutes to do so it’s worth a shot!