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Wiper Gremlins

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pseudomike

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Ok guys, please help....

I have an old 3/4Ton GMC that I am almost done doing a frame up on. :D I've replaced every body panel, the cab, springs, motor, you name it. It's been a lot of work, and it's getting close to done...except for some gremlins...namely the wipers.

I bought a bare rust free cab from a guy for the project, it was bare so I transplanted the entire wiring harness out of a'91 Blazer into thes truck. I mean every wire, including injection, pwindows, cruise, A/C...every single wire. It's running the '91 gauge cluster, the '91 column, all brake switches, sensors, motors, even the rear ABS unit. So on the weekends I have been assembling this truck and so far so good. The truck started and ran, the headlights work, A/C, dummy lights, cab lights, interior lights and so on.

Then, this weekend I goto hook up the wipers and well that is when it got interesting. The wipers are the delay type on the column, no external switch..and the story is that when I flip them on they work, low speed, high speed. The washer works, but the delay, well the dealy has a mind of it's own. It never really delays, sometimes high speed sometimes low...sometimes they won't even shut off until I put the switch back into the low or high speed position. And the washer, yup it washes...but sometimes the wipers just stay on. So I tried changing the motor aout and it is the same problem. I'm beginning to think I need to dig into the column and replace either the delay module or the switch under the steering wheel.

If someone has a simpler check, or knows a good way to troubleshoot this please let me know...i'm trying to wrap this thing up before the snow flies and I have enough to do without these little things holding me up.
 
Tonight I'll see if the '91 manual covers wiper troubleshooting in-depth, I expect it does.

If so, I'll shoot some high-res photo's of the pages and put them up on my webshots album, and link it from here.

You say every wire was swapped, so I assume this includes the wiring for the wiper motor in the engine bay as well? The wiring plugs were the same for "early" vs. "late" wipers, but the wire position and number was different, only reason I bring that up.

I need to brush up on this myself. My truck hasn't done it for a long time, but every once in awhile, the wipers would either just start working by themselves, or not stop after I turned them off.
 
dyeager535 said:
Tonight I'll see if the '91 manual covers wiper troubleshooting in-depth, I expect it does.

If so, I'll shoot some high-res photo's of the pages and put them up on my webshots album, and link it from here.

You say every wire was swapped, so I assume this includes the wiring for the wiper motor in the engine bay as well? The wiring plugs were the same for "early" vs. "late" wipers, but the wire position and number was different, only reason I bring that up.

I need to brush up on this myself. My truck hasn't done it for a long time, but every once in awhile, the wipers would either just start working by themselves, or not stop after I turned them off.
Click to expand...


When you figure out your problem let me know.
I have the same problem, I would be driving and suddenly they start working, or I start and then turn them off and they keep going for 10-12 times.
My guess is probably the wiper motor contacts inside it but if you have tried that then what else?
the switch??
 
Every wire..right down to headlights, charging/starting system was swapped. The column, wiper motor, and washer tank were all from the donor. I of course don't remember checking the wipers in that truck. I also had the column apart to fix the notorious GM tilt wabble so I may have pinched a wire? I am going to check wiring before anything else.
 
I know mine aren't pinched (just had them out to do the cruise) but yours could be, never know. Won't hurt to test them.

I wouldn't be surprised in my case that the motor is the problem, sitting long periods without being used while in a damp climate, pretty good recipe for some corrosion on any contacts.

As bad as those modules are (anyone else noticed that the fastest setting for delay results in continuous wiping, yet the difference between that and the next "slowest" wiping is huge?) I wouldn't be surprised if they are the problem. I've got a few modules, tested them, one was obviously bad (no delay) while the others all operated the same way...big difference in slow delay vs. high delay, little inbetween. Still much better/necessary than no delay, just not a smooth progression.

If my problem were consistent, then the troubleshooting info I am assuming the manual contains, would be worthwhile.

For the OP, the module is the box under the column...that's it other than the stuff at the top of the column, for hardware anyways.
 
I have some parts to test it with thankfully. Should note that the other motor I tried was not new...but it would be very odd if it acted the exact same way. Being that the truck has been all apart I am thinking I will check the grounds first, then probably the delay module. I will keep you guys posted...and of course I am open to any ideas.
 
Crossing Fingers

Ok left work a little early today because it was nice out and basically supposed to rain the rest of the week. Ended up dropping the column down out of the bracket and inspected the wires that I could see. Not much to note so I turned the wipers on...crazy operation as expected..and I started tilting the column and wiggling the wires with no luck. Then I went out under the hood and started playing with the pigtails on the motor and whola...normal operation. After pulling the top pigtail off I noticed that the wires inside the connector were crroded so i cut them and resoldered..lil dielectric grease..and it works fine. Wiggled wires a little more and no effect. I'm guessing this was the problem...if I unplug this connector with the wipers on it does exactly what it did before, just keeps wiping. Still keeping my fingers crossed but I will report back if re-emerges. maybe a simple fix for a lot of you guys.
 
That's good news!

If mine starts acting up again, I'll have to try that. Simple stuff first, eh? :)
 
Those would have been usefull....lot easier than trying to guess how the circuit works. I'm printing them out in case I ever need them.
 
dyeager535 said:
For continuity, here is the manual section for the 1991 R/V/P trucks. Includes wiper motor and washer. Hopefully if others search in the future, they find this. This should be for all the trucks with the column mounted wipers.

http://rides.webshots.com/album/561141704fFWVEz?vhost=rides
Click to expand...

even though i have the ancient high/low version of wipers with the dash switch, this was still very helpful... :waytogo:

2471318790097469480DYtHuG_th.jpg
 
This sounds like some typical delay module malfunctions. We hav these pproblems on the Subs at work all the time. Usually erratic delay or none at all, sometimes washer won't work or intermittent, sometimes wipers come on by themselves. Module should be on firewall. My delay and washer haven't worked for years, but I just ignore it cuz my wipers don't come on by themselves yet.
 
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