I had interval wipers, defroster (fan motor), and headlights on and suddenly the wipers stopped. I was driving down the interstate in a pouring rain and fog. I noticed that the dash blinker lights were dimly on and so was the cab light. If I turned off the headlights and fan the wipers would work but at about half speed but the blinker and cab lights remained dimly on. If I turned on either the fan or headlights the wipers would stop with a clicking sound coming from under the dash down by the passenger's feet.

Everything went back to normal after a few minutes and then the problem occurred again. One the return trip that evening it was no longer raining and when I first got into the truck everything was OK. I figured it was due to moisture and now had dried out. The problem reared it's ugly head once more and I had to drive all the way home with headlights only and had to wipe the fog off the inside of the windshield with a rag.

I drove it yesterday (dry day) and all was well. Coming in to work this morning I decided to check it out and now the wipers won't budge even if I turn off the headlights and fan.

Any ideas? I'm stumped.

 

I had that problem with my 89. finnally found that there is a circuit breaker inside the wiper switch. replaced the wiper switch, and now all is well

 

Sounds like you have a bad body ground (not frame).
Clean the body ground and if need to run another ground wire (10 GA) from the NEG (-) post of the battery to the body.

Sometimes this happens when you have a poor ground at the engine block and the starter tries to ground through the body. Sometime this can occur if somebody grounds the frame instead of the engine block.

 

I ran my new ground from the neg terminal to the bolt that holds the radiator on at the top. I had forgotten that one.

 

Where is the wiper switch? Is it in the turn signal handle or is it what is down by the passenger's feet?

I've already replaced grounds. I was having other issues a while back that turn out to be a bad pos battery cable.

 

The switch is in the turn signal handle. The controller unit is down by the passenger's feet.

What part of the truck did you hook the new ground cable from the NEG battery post to?
Do You have a wire with the new ground cable running from the NEG post to the body?

 

I ran a 10 gauge wire from the battery to the dash ground at the passenger's side kick panel and then another from there to the drivers kick panel.

Its not actually running from the neg post. It is running from the inner fender well ground spot that the neg battery is bolted to.

 

OK now I have no fan and the wipers move really slowly. Sometimes I have to help them return. And when I have the wipers on the turn signal arrow lights in the dash and the interior cat light are on really dimly.

Am I still looking at the switch?

 

Try a set of jumper cables hooked from battery ground ( both pos and neg on one end of cables to neg on battery) than put other ends (one on frame and other on body). If it helps than it is still a bad ground. Hope this helps.

 

I will do that. Jumper cables come in real handy for that kind of thing.

Out of curiosity, why does it seem like a ground problem?

Why does turning on the wipers (that move real slow) which turn on the cab light and dash blinker arrows lights dimly sound like a ground.

That and the no fan?

 

When ever ya have dim lights or slow motors it has always been a ground problem with me. Most people will look to positive side for the problem and seldom do more than clean the neg side. If the battery is good than low volts are almost always a ground. And low volts is what you have making the dim lights and slow motors. If ya had a major current draw that was robbing the power than something would be getting hot and fast. If nothing is getting hot than ya have low volts not a power drain.

 

I like your thinking. But why would turning on the wipers turn on other lights? That's what stumps me. I don't understand the connection between the wiper switch and the dash blinker arrows or the interior cab light.

I do appreciate your help.

 

Ya may have other problem also. But I have seen a bad ground do this. The wiper motor is looking for more power. It can't get it from ground. Remember ground carries as much current as positive. So the motor is back feeding through the pos side. The lights that are affected are also starving for current so they are the first affected. Maybe on the same circuit.Try hooking yer jumper cable from batt ground directly to the wiper motor housing or fire wall close to it.

 

OK then, I'll get that ruled out. The lights must be coming on because the wiper motor is somehow back feeding through them.

 

Is this prob on the 92 or the 72? On the 92 everything you are having problems with are in the steering column with needs grounded separate from the body and chassis. On ether one I would try a test ground on the steering column above the dampener that hooks the column to the steering box. Most columns are rubber mounted to keep vibrations out of the steering wheel. On the 92 I think it is grounded in the harness and may be corroded. on the 72 it is probably grounded to the fire wall outside. Just thinken here bud.