89 K2500 windshield wiper issue

[93chev6.5diesel]

My 89 K2500 has developed an intermittent wiper cycle with the control off. This first surfaced about 18 months ago or so. I changed out the motor as I was told that was the problem. But I think it wasn't because the wiper cycle is back. I don't drive the truck at all really and just use it to plow snow and have the wipers on when doing this so I haven't noticed that the problem was still there until today when I took the truck for a ride to get some fuel and clean her up for the coming season. Can I buy just the brain box on the side of the wiper motor? I asked at AutoZone and they said no. Thanks for any help.

[Schurkey]

Wild-Ass Guess: The problem is the wiper switch, not the wiper motor. A REAL GM service manual would be a great help. Available on eBay for a fraction of the "New" price.

[93chev6.5diesel]

The actual column signal light/wiper switch? Or the pulse board on the wiper motor? I have the earlier pulse board which is no longer available as a possible repair.

[Schurkey]

Originally Posted by 93chev6.5diesel

The actual column signal light/wiper switch? Or the pulse board on the wiper motor? I have the earlier pulse board which is no longer available as a possible repair.

I know about the circuit board problems as I have a Lumina that had issues; and discovered as you did that there's zero aftermarket support for the circuit board. I had to buy an entire wiper motor with board from a salvage yard. All the wiper motors sold by parts stores as "rebuild" do not come with the circuit board.

If that's what your truck has...I'd be looking in the salvage yards.

Even so...it's worth your time to buy the service manual. I have this nagging feeling that there's a capacitor-and-charging-circuit in the turn signal stalk or in the steering column switch, and when the capacitor circuit fails, the intermittent wipers are affected. The rotation of the delay knob changes the rate that the capacitor is charged, when fully charged, it discharges into the wiper motor causing one swipe of the wipers. Then the capacitor is gradually re-charged at a rate dependent on the position of the knob.

OTOH, I haven't had to deal with this on my truck, and I might be way off-base.

[TiVoPrince]

Is
there a photo or repair guide out there? The old style module for intermittent wipers seems to go sideways now and then. No rhyme or obvious reason that I can trace.

Symptoms:
Start wipers, fast, slow, intermittent it does not matter they continue working uncontrollably until you turn it off with the key or unplug the module.

Observed faults:
Won't shut off. Wipes in regular mode once turned on until you shut down with key
Wiper "parking" is a hit-miss proposition (highly frustrating when combined with above)
Washer is functionally intermittent. Motor and wiring tests good but combination falls off

I have four of those wiper control modules that have been solder refreshed but seem to have a repeated unknown expiration date that is simply not clearly stamped on them. I tend to keep a pick to free the wiring connector, torx15 and the next tested module in that under hood box.because it remains a mystery why they go sideways for no knowable reason. Yet they will work properly at some future date.

After all this time I'm inclined to chalk it up to the effects of sunspots (moonbeams at night) or some other unknown force in the universe. Perhaps its just my karma just a little out of adjustment...