Weird electric windows, locks, and wipers... Help!


Old 10-01-04, 11:39 AM
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Question Weird electric windows, locks, and wipers... Help!

Recently acquired a 1988 GMC Truck. Electric windows and such worked OK when I looked the truck over, but the switches didn't respond too quickly (meaning there seemed to be a lag, or having to hit the buttons twice before they'd work...). After spending a few weeks with my new truck, I've found the following troubles and the times when they occur: Sometimes when I get into the truck, the electric windows, locks, and windshield wipers work flawlessly. Other times, I get in a crank the beast over, the windows and locks won't work at all and the wipers work whenever they want (example: hit "mist" and they run on for as long as they want and they won't turn off until they feel like it and then they shut off in varying positions on the windshield and keep trying to "run". Other times, when you hit the intermittent, or slow, etc., they keep running on...) I may stop off at the store for a few minutes and get back in the truck and they may work fine again. There doesn't appear to be any pattern of when they do this. The only thing (at least that I've noticed so far...) is that if the windows and door locks work OK, so do the wipers. When the windows and door locks don't work, the wiper go wacky. Anybody got any good ideas on what the idea may be and how to fix it, besides blowing it up, I mean... Oh yeah, I've sprayed the electric locks, windows, and wiper control with a good contact cleaner. The only thing that did was help the windows and locks work a little more "crisply" (when they work that is...) Thanx
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Old 10-01-04, 07:58 PM
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I wonder if you have ai intermittent ground problem that may be common to the items you are having trouble with. You can try running a good ground from the wiper motor for example and see if it helps.
Old 10-01-04, 09:26 PM
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For the windows and locks, you could try checking the wires going from the door to the body. They usually are run in a black accordian-like tube from the door to the cab area near the hinges. The wires inside these tubes tend to break over time from opening and closing the door.
If you dont find any broken wires, check your grounds and make sure they are clean and tight.
Old 10-02-04, 03:48 AM
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I have difficulty believing the door lock and window problem and wiper problems are related.
The next time the wipers continue to run when shut off, try taking a screwdriver handle and tapping on the wiper module, which is the black cover on the wiper motor. IF this corrects it, it needs a new module. They are notorious for this.
As for the door lock/window problem. ....connect one lead of a voltmeter to the battery negative post, and the other lead to one of the brake lines coming off the master cylinder, and then operate either the locks or the wondow switches, the reading on the voltmeter should be less than a half of a volt. This is called a voltage drop test and will tell u if your chassis and body are grounded properly.
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