Wiper switch/motor troubleshoot?

[seanconnery]

This may seem really lame, but how can I troubleshoot my wiper switch and/or motor to see which ones broken so I can replace accordingly? I've checked the fuse and it's good, but I get nothing when sliding the switch. It's a 1981 GMC, and the switch moves horizontally to 3 or 4 positions and the switch itself is round with an arrow that rotates clockwise. The wipers didn't work when I bought the truck and I'm just getting around to fixing it now. Where can I start?

[LONGHAIR]

A test light will tell you if you are getting power to the terminals. Un-plug the harness and probe the connections.

[babyJay]

If it isn't working on any of the settings (switch) I would venture to guess the motor is bad. Like Longhair said, use the test light. If you have an ohm meter you can "ohm out" the motor to see if the windings are open "OL" is what you'll see on the scale, or MegOhm readings. If it were shorted internally it would blow the fuse. You also have relays involved if you have delay wipers that could go bad.

[BLE 'BURBAN]

May be the delay module is fried as well. it simply plugs inline between the switch and the harness under the dash. unplug it and plug the harness directly into the switch to see if your wipers work. If not replace the switch and check again with and without the delay module. Still nothing? Replace the motor.

[seanconnery]

Sorry to bump this thread back up, but I have more problems. I got a wiper motor from ebay that doesn't have all the junk on the front like mine does. I'm guessing this extra stuff is for the delay feature. The plastic cover is flat, whereas on my factory one the cover bumps out for the extra parts. Theres a spool of copper wire, some springs, and other junk. Can this be swapped over to my new motor? Or can I swap only the motor assembly from the new one onto my factory one?

babyJay also mentioned above that since I have delay wipers that there are relays in the wiring. Maybe my motor and switch and delay module are fine and the relay is shot? Where is the relay?

RANT ALERT!:

I could really use some help here, cause I'm getting sick and tired of driving this truck only in my zipcode while being afraid of dark clouds in the sky!

[seanconnery]

Update: I pulled the motor out and tested it independintly of the wiring harness and switch and it works. Does this automatically mean the switch is bad? I tried it with and without the delay module plugged in and got nothing. Is there a way to bench test the switch seperate of the wiring harness? What are the odds that the wires are goofed up coming to the motor?

[mhicks]

It hink the stuff you are refering to on the outside of the motor "parks" the wipers in the down position when you turn them off.

[seanconnery]

All I know is that it moved and I saw it run when I plugged my test leads into the battery. I used my service manual to see what terminals to connect to operate it in "low". So I put the motor on top of the core support in front of the battery and tried it and it worked. So what do I do now? Just assume the switch is bad and pay $40 for one from a catalog?

[seanconnery]

*UPDATE*

Ok, now I'm begging and pleading. I know someone out there can help me out. I bought a brand new switch and installed it and still nothing works. As I said before, I pulled out the motor and tested it without using the harness according to the service manual and it works. I looked under the dash and under the hood for any loose grounds and can't find any. The fuse is good. Does anyone have any advise?

*EDIT*
Can someone, anyone get a pic of where the ground strap that grounds the wiper motor to the firewall is located? I think this might be my problem. I don't recall there being one when I removed the motor last week, but I could be wrong. I heard something fall off around the motor when I pulled it out, but i thought it was a socket I had sitting on top of the firewall that I knocked with my hand, and fell underneath the truck. I crawled underneath and grabbed it and didn't see anything else.

[seanconnery]

How are you guys just bypassing the delay module and plugging the switch right into the factory harness? I don't get dick when I try to omit the module. I know the motor's good, and I bought a new switch so that should be good, so why do I have nothing? At this point, I don't care about pulse wipers. I just want wipers that work.
Seriously, someone has to have gone thru this before.

[hrc200x]

I'm no expert, but here is a couple suggestions. Do you have a test light? You might want to make sure power is getting to your switch inside the cab first. If it is see if power is comming out of the switch. If so follow the wires from the wiper motor to the firewall and remember which ones they are. If its possible unplug all the wires on the backside of the fuse block (outside of the cab). Should be 3 seperate blocks of wires. Plug in the one that comes from the starter/battery this one should supply the whole cab with power, the other two are mainly for headlights and tail lights. If the wiper motor wires came from one of the other blocks of wires that are unplugged try test lighting them.

[seanconnery]

*UPDATE*

I'm now getting 0.001 Volts readings from terminals "A" and "E" on the harness as it comes from the dash. I also get the same readings with the module plugged in. When the switch is plugged into the module, terminal "A" reads 0.001 V, and terminal "E", which I think is the ground, reads "OL". I guess it reads "OL" because I don't have it bolted down to the dash. It doesn't matter if I do have the switch bolted down though, because when I tested the 3 plugs that go into the motor with everything secured (motor, switch, ignition ON) I got the "OL" reading on every terminal.

So, to sum it all up: good power is coming into the switch, but nothing is getting to the motor, unless I tested it wrong. Suggestions?

When this is all done, I might write a complete tech article on how to troubleshoot and fix all this. BTW, my hair is turning white from trying to figure this out.

[seanconnery]

I got my truck back from the mechanic and the wipers are now fixed. It turns out the circuit inside the fuse box that controls the wiping system (motor, switch, fuse, everything) was bad. That's why all the parts I bought were not working. My voltmeter tests however were still good - I don't know why and right now I don't care. He ended up hand making a wire and inline 25 amp (factory fuse) fuse to bypass the faulty circuit. Cost me $58 for him to do it. Cost me $90+/- for new parts that probably didn't need replacing. Just goes to show you that you can have everything testing fine and still have a defect somewhere.