# 86 Chevy Truck wipers possessed



## Tad Johnston (May 5, 2008)

I have an 86 Chevy C10 pickup that - when I first turn the key on - cycles the winshield wipers 4 times. This first started 10 years ago. It went on for almost a year and then stopped until just recently. It doesn't happen every time you go to start it but 9 times out of ten it does. The turn lever control has been replaced serveral times and I tried swapping out the wiper motor - and still it goes on, 4 swipes and then park. Not only does it look strange but my blades are all worn out by the time I need them.

Anyone got any ideas??

thx


----------



## mack1 (Nov 27, 2007)

Hi Tad,

1986 was a poor year for windshield wiper controls on S10's. The control circuit that triggers the wiper motor is succeptable to electrical noises. We had one and it would sometimes make a wipe while just driving down the road. If you tear one apart, you will see a true piece of junk. It uses a printed circuit board with a wiper contact that rides on the circuit board. (again, true junk) No good solutions, I think I ended up soldering a resistor between the input and ground to help the problem. Ford was careful not to steal that idea form GM.

It might be as simple as changing a capacitor at the altenator to ground (I recall it had one), but no clear solution.

Guess that's no help at all. They probably had a recall repair for it, but it was never advertised. 

Regards,
Mack1


----------



## Tad Johnston (May 5, 2008)

Mack1:
Thanks for the quick reply. Allow me to muddy the waters a bit more if I can. Firstly, My truck is a C10 not an S10 but I doubt that changes things much. I am aware of the crappy control board issue and am told that NAPA even sells a replacement, but I am unconvinced that this is the problem because one of my last troubleshooting steps was to replace the wiper motor with a know good replacement, and the same symptom occured immediatly - as soon as I turned the key from lock to run the wiper blades cycled 4 times. This has always been the only issue with the wipers themselves, I don't get random wipes, or failure to work at all or any of the other weird control board issues I've read about. Everytime I turn the key on the blades go up and down 4 times - no more no less. besides - isn't the control board issues mostly related to electrical noise? Not a lot of interferance being generated when the engine hasn't even been started yet.
Usually, this problem goes on for a few months and then 1 day I'll notice the wipers didn't cycle and the problem then hibernates for anywhere from a few days to a few years. Eventually it comes back...it ALWAYS comes back.
Well, I might just have some new useful information - in between writing the last paragraph and this one I thought 'Don't the wipers cycle 4 times when you depress the WASH lever?' So, I tried to verify that by running the washers and discovered they are not working. I don't know for how long though as I rarely use them. The washer motor has power but I think I remember that works by grounding the washer motor when the lever is rotated. BTW - truck has seperate wiper and waser motors not the combined unit I've had on other trucks.
So, that would appear to take us back to the multi-function T/S switch, but I know that switch has been replaced at least 3 times, once just recently.

NOW YOU KNOW WHY THIS IS BUGGING THE CRAP OUT OF ME!!!

The only thing I can think of at this point is that somehow that washer pump gets grounded briefly ONLY when the key is first turned to 'RUN'. This causes the wipers to cycle just as they would when you wash your windshield. If this is true the problem wouldn't be the wipers as they are the symptom and not the cause. Short between the ignition switch circuit and the washer circuit? Is that possible/likely?

So - yeah in the grand scheme of things, this is a minor problem. But it's a minor problem that's been kicking my a** for several years. So how about one of you smart guys out help me figure this out before I give up and it wins! NOBODY WANTS THAT!

thxs...tad


----------



## Raylo (Feb 12, 2006)

Hey, Tad. See my post here: 

http://www.techsupportforum.com/f155/92-gmc-jimmy-4-3-ltr-cfi-problems-247073.html

Perhaps it's not likely but if you have an intermittent ground causing the problem you might check the insulation on the wire bundle coming through the firewall near the shift linkage. I'd bet the wires for the wiper are in there. The tranny problem I had drove me nuts for a while before I thought to trace the wires.

As I said, not likely but if you are otherwise stumped it can't hurt to check this and/or trace out other wiper wires.


----------



## mack1 (Nov 27, 2007)

Hi Tad,



> The only thing I can think of at this point is that somehow that washer pump gets grounded briefly ONLY when the key is first turned to 'RUN'. This causes the wipers to cycle just as they would when you wash your windshield. If this is true the problem wouldn't be the wipers as they are the symptom and not the cause. Short between the ignition switch circuit and the washer circuit? Is that possible/likely?


You might be on to something there. I don't have any electrical prints that date back that far, but newer prints show that the 4 cycle thing is handled in the electronics in the wiper motor assembly. (when you changed the motor, I'm assuming you changed the whole thing and not just the motor itself) I also noticed that the wiper circuit is made hot by the ignition switch being in either Run or Accessories. If your wipers will work in the ACC position, does it do the 4 stroke thing when you switch it to there? 

The newer prints don't show a switched ground to cause the washer to work. A positive voltage from the washer switch is applied to cause it. 

Hope this might help,
Mack1


----------



## mack1 (Nov 27, 2007)

Hi Tad,

Thought I'd go ahead and send a picture of the circuit I have. It if from a Haynes Repair Manual for Cherolet Silverado 99 through 2005.

May not help, but something to look at. The color codes on the wires might be the same as yours.

Mack1


----------



## Tad Johnston (May 5, 2008)

Raylo said:


> Hey, Tad. See my post here:
> 
> http://www.techsupportforum.com/f155/92-gmc-jimmy-4-3-ltr-cfi-problems-247073.html
> 
> ...


Raylo;
I appreciate you taking your time to try to help. When I replaced the wiper motor Assy (not just the motor) 2 years ago I noticed some firewall grommets were missing so I replaced them all. At the same time I rewrapped any portion of the harness that looked even slightly damaged. Then I covered all wiring in the engine compartment with flexible plactic tubing - so I know all of that is OK


----------



## Tad Johnston (May 5, 2008)

To all trying to help:
I got called away on business last night so it'll probably be a couple of days before I can pick this thread up again. Bear with me - I'll get back to it soon!

thxs...tad


----------



## RIGHTE0US (Jan 7, 2008)

the washer switch is to connected to the wiper motor on that truck. Chevy has had them connected since the 70's. Even though on seprate switches, it's still combined to interact with the wiper motor...spray, wipe 4 times, then off. That's the cycle.


----------



## steinerct (May 27, 2016)

Tad, did you locate the wiper problem? I have identical problem with my 86 C10, turn the ignition on and wiper makes 4 cycles. What did you do to correct the problem. Thanks for your help


----------



## Basementgeek (Feb 7, 2005)

Tad has not been here in over 8 years........

BG


----------



## Vince G (Jul 16, 2016)

I know it's been over 8 years, but I have the same problem, 4 wipes and no washer, with my 85 K20. Has anyone fixed this?


----------



## kendallt (Feb 21, 2007)

Last time I had a GM, I switched pretty much everything that was associated with the wipers and still had the issue. 
My ultimate fix was to install a simple on-off switch on the dash.


----------



## Wrench97 (May 10, 2008)

2 speed wipers or does it have interval(delay/mist) wipers?

If it has interval then it's probably in the pulse control module, if it's 2 spd then I would look at the park switch in the wiper motor.


----------

