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More @#%&* wiper trouble

Bill Monk

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I bench tested the motor and it works fine. I replaced the switch, hit the button and the wipers worked. Problem solved right? Not so fast, the next time I turned them on, the wipers moved but at a snails pace, like barely moving at all. When I turn the switch off, they park normally and at a normal speed. I cleaned all the connections at the firewall and still no change. It's clearly a short but I can't find it so my question is how do I get around this? I can run a hot wire straight to the brown wire on the motor but that will give me only high speed. Does anyone make just a wire harness for the 3 speed wipers or am I looking at buying a whole under dash harness to get what I need?
 
I bench tested the motor and it works fine. I replaced the switch, hit the button and the wipers worked. Problem solved right? Not so fast, the next time I turned them on, the wipers moved but at a snails pace, like barely moving at all. When I turn the switch off, they park normally and at a normal speed. I cleaned all the connections at the firewall and still no change. It's clearly a short but I can't find it so my question is how do I get around this? I can run a hot wire straight to the brown wire on the motor but that will give me only high speed. Does anyone make just a wire harness for the 3 speed wipers or am I looking at buying a whole under dash harness to get what I need?

I got my harness from Classic Industries
 
I suggest you check your ground. Isn't there a funny little ground strap on those that goes from one of the bolts to the firewall or something?
 
I suggest you check your ground. Isn't there a funny little ground strap on those that goes from one of the bolts to the firewall or something?
Yes but I tested the motor on the car and it works. I just can't get it to work properly from the switch.
 
Doubting the short, should be blowing fuses if it's shorted. Double check all connections including bulkhead and double checks grounds. Run a wire from negative post to the wiper as well so you can eliminate the ground as the culprit. Last dont ever assume because it's new it's good, 100% of my problems during my build were new parts that didn't work.
 
Doubting the short, should be blowing fuses if it's shorted. Double check all connections including bulkhead and double checks grounds. Run a wire from negative post to the wiper as well so you can eliminate the ground as the culprit. Last dont ever assume because it's new it's good, 100% of my problems during my build were new parts that didn't work.
I tested the motor on the car by simply running a hot wire to the brown wire on the motor and it worked fine on high speed, then I joined the brown and red and connected to 12v, ran a jumper from the neg bat post to the green and it also worked at lower speed. I'm confident it isn't the motor or motor harness to the bulkhead. The problem has to be somewhere between the switch and the firewall, I just don't get why they would run but at such a slow pace. I mean you could go make a sandwich while you wait for them to make a single pass across the glass.
 
I tested the motor on the car by simply running a hot wire to the brown wire on the motor and it worked fine on high speed, then I joined the brown and red and connected to 12v, ran a jumper from the neg bat post to the green and it also worked at lower speed. I'm confident it isn't the motor or motor harness to the bulkhead. The problem has to be somewhere between the switch and the firewall, I just don't get why they would run but at such a slow pace. I mean you could go make a sandwich while you wait for them to make a single pass across the glass.

That's weird. It almost "sounds" like your wiring is giving it 6V instead of 12V. That's what made me think it was a ground issue....working, but barely.
 
Isn't there a 5 volt reducer in the gauges? Could that be the problem......
 
Sounds like the power source, to the wiper switch, or the switch itself. That's what I'd look at, besides the wiring. Bad/corroded connection somewhere.
 
Sounds like the power source, to the wiper switch, or the switch itself. That's what I'd look at, besides the wiring. Bad/corroded connection somewhere.

Good point. Too bad most people don't have an extra 3-speed wiper switch laying around for a test. It would be a PIA, but maybe you can jump past the wiper switch at the switch's plug? Maybe that will tell you something.
 
Good point. Too bad most people don't have an extra 3-speed wiper switch laying around for a test. It would be a PIA, but maybe you can jump past the wiper switch at the switch's plug? Maybe that will tell you something.
I'll check it out. I just replaced the switch but that doesn't mean it's good. Strange thing is when I first replaced it, they worked and now they don't. Have I mentioned I hate electrical stuff!
 
I take it that it is a 3 speed motor ?? If so they work on a shunt field winding to control low and medium speed as they put resistance in the shunt field for medium speed. If you have a two speed switch on a 3 speed wiper motor that can cause problems. And of course check you grounds real good. Ron
 
I take it that it is a 3 speed motor ?? If so they work on a shunt field winding to control low and medium speed as they put resistance in the shunt field for medium speed. If you have a two speed switch on a 3 speed wiper motor that can cause problems. And of course check you grounds real good. Ron
it is a 3 speed motor and switch
 
Start by testing the different wiper speeds first and being sure the motor and assembly under the cowl move the wipers correctly.

1. There is a thread called "bench testing a wiper motor" on youtube or on this site somewhere. Super easy.

2. Put an extra ground in place and see what happens; another ground cannot hurt. I made a 4 inch ground wire and attached it from a housing bolt of the wiper motor to the firewall and my wiper motor came alive. The wire is barely noticeable.

3. If only the slow speed works, you should be able to test the higher speeds by using a test lead/5 feet of wire from the positive terminal of the battery to the different electrical contacts on the motor itself for low, medium and fast speeds. As soon as you connect the positive lead from the battery to the switch contacts at the motor itself, the wipers will start moving even if the dash wiring is incorrect. I tested and ultimately fixed mine this way. Then when I was sure the motor worked correctly I repeated all tests at the bulkhead contacts, THEN went to the switch in the interior and tested it. Turns out one wire was attached in the wrong place on the dash switch. My original dash harness doesn't have the wires labeled like aftermarket harnesses do.

4. It also might help to keep a 4-5 foot 16-18 gauge red and black wire with alligator teeth connectors on each end for quick testing of this and other things as you come across them on your car.

5. Finally, I recommend copying and pasting different threads into a word document for your car. Whenever I come across electrical gremlins, the threads on this forum help. I scour through them and copy the good ones to my own personal troubleshooting manual for my car. If I ever sell it, the new owner will get the manual which could save hundreds of hours to a future owner. With no experience in auto mechanics, I fixed all my dash gauges that never worked by reading threads on this forum.

But other things like changing the original bushings on a lower control arm are OUT of MY league and level of expertise at least for now.
 
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