1999 Plymouth Voyager wipers out of control

Hi stevenm2. Welcome to the forum. The wipers are controlled by a very trouble-prone Body Computer. I haven't heard of them causing the wiper motor to run constantly, but causing them to not run at all has been a very common problem. A bad motor ground will cause that too, but based on the two symptoms, it sounds like a computer problem. The Body Computer is bolted to and plugged into the fuse box above and in front of the brake pedal.

caradiodoc

OK, thanks. I take it that the Body Computer is the item marked "A" in this picture I took just now...I also assume the items "B" and "C" are not it. How do I get that out of there?

It's item "A", but it looks different than I remember from ten years ago workng at the dealership. The plugs on the bottom are connected to the computer, but I remembered it as being in front of the fuses and up higher. There are three 5/16" head bolts holding them together, then you pull the computer straight down to unplug it.

caradiodoc

OK thanks for that, but now I have a dilemma - I took another drive today and tested the wipers again. They worked! Now I am afraid to mess with it. Perhaps there is a bad ground somewhere, as you mentioned before? Or dirty contacts? Is it possible for the BCM to have an intermittent problem?

Anything is possible when a computer is involved, but in my limited experience, every time the Body Computer has been at fault, the wiper motor was dead in all speeds. That said, I'm working with another fellow with similar problems on a '97 model. His only works on the high speed.

There have been problems with the ground strap on the motor mounting plate making poor contact under the mounting bolt head, but that will cause the motor to not run. The park switch turns on in the park position to ground the sensing wire. That tells the computer to turn the motor off. If the problem acts up again where they don't turn off, use a piece of wire to ground the dark green / white wire in the motor's connector. As long as it's grounded, the motor should not run. If it does still run, that wire has a bad connection or the Body Computer is defective.

If the motor stops when the wire is grounded, suspect the park switch inside the motor. The fix would be replacing the motor.

caradiodoc

The turn signal relay causes this problem. It has a small circuit board that interacts with the BCM. A solder joint cracks (easily repaired) and messes with the wiper operations. It happened to my brother's voyager van and the repair of the relay cured it. It was an intermittent problem.