For the second time in three years, my wipers have defaulted in ALWAYS ON. First repair dealer replaced wiper motor. This time, I'm trying to fix. Easy to get at, just remover wiper arms and snap off plastic cowling. Replaced motor and.....still doing it. Have to remove fuse to turn off! Took old motor apart and no pulse control circuit board. So, where is that pulse module? I'm discovering its integrated with the body/chassis control unit, located above the gas peddle. Not that easy, that module has to be programmed at the dealer. It also controls cruise and remote entry, so I'm told.
Scared to touch, but is that how to fix the wipers?
You'll need a high-level bidirectional scan tool to diagnose that. That's just the way it is with modern vehicles where everything is controlled by computers instead of simple electrical circuits.
not everything can be solved with scanners. Even if the wipers are computer controlled, you would only be able to command them on or off, which doesn't get you very far.
Maybe not everything but a good scanner would be the way to diagnose this problem
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In fact I was going to respond to this question with one of my long-winded system descriptions complete with color highlighted wiring diagrams but @chucktobias provided a good answer
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With a good scanner which can access BCM live data All of the wiper/multifunction switch position inputs to the BCM could be observed (ruling in or out a problem with the wiper/multifunction switch), and then the wipers could be commanded on in low and high speeds to see if the bcm was trying to control the 2 pcb wiper relays
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Then using a test light at the wiper motor connector it would be easy to see if there was power on the wiper low speed wire and the wiper high speed wire when those relays were commanded to energize and the 3rd wire that keeps the motor running until the Park switch grounds/brakes the wiper motor when the wipers are turned off
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So here, a good scanner would cut down diagnosis time by at least an hour (maybe more) than using a multimeter but a good old fashion test light would also be needed at the motor to nail this down to the exact problem
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((not choosing sides, just sayin'))
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I stand corrected.
My answer was based on experience with my own vehicle, which I see now must be very-low tech compared what you are showing me. I had no idea the computer control went so deep.
It also makes me even happier with what I have! 😆
Same here, @mmj, I'm keeping my old rides running as long as possible. The level of computer control in modern vehicles is insane, turning what should be simple repairs into crazy expensive nightmares. Why the heck should headlights and windshield wipers be computer controlled? Way too often the answer to peoples' car problems here is "you need a $6000 scan tool to diagnose that".
I can understand trying to extract more efficiency out of an engine, but this is going way too far. Totally unnecessary.
where is that pulse module?
in the BCM
Most likely you have a problem with the control stick
So, replaced main fuse box located under the hood, driver side. Wipers now working. Simple plug and play install. Lot's of harnesses to remove and reattach, but one hour job. Part is $250 C only available dealer, who also installed mine (Brrrr..cold in my garage).
Good work I guess, though I can't understand how a faulty fuse box could cause wipers to stay on.
It's because his wiper relays are PCB relays (non serviceable) soldered onto the circuit board in that underhood fuse box