M-1028 wipers quit working

[Zero_cool]

Since I bought my truck the wipers have been slow and stop at random.
Yesterday they finally quit working at all.
So i took my test light and checked for power to the wiper motor.
With the key on and the wipers on high I only have 2 wires that are hot.


.8 WHT-93 A --- going to the suppressor assembly

.8 WHT-93 B --- going to the WASH
SOL

Are there any other wires that should be hot or is this it?
I will check the voltage tomorrow.


Electrical is not my thing but i am slowly learning.

 

[Anubis8472]

I have a similar (if not same) issue.
I havn't had time to check it out yet.
Winter = dark when I leave for work, dark again by the time I get home.
Maybe this weekend I'll get a chance to check mine out (though my pickup's front brakes ceased, so that may tie me up).

Mine will work strong sometimes, work slow sometimes, and periodically stop working.
When they do stop working I try to turn the knob off, then back on and it does nothing. However, when they quit if I hit the washer, they start working again.

I'm guessing the issue is not with the motor itself, but more likely a bad connection somewhere, or a bad switch.

My work truck (freightliner) has the opposite issue. It starts with the wipers swiping acrost by themselves when you hit a pot-hole. Then progresses over time until the wipers just randomely turn themselves on and can't be turned off. Been through 4 turn signal/wiper switches. I'd love to have the old style dash mounted switch again.

The CUCV turn/wiper arm might be the culpret in this case as well.
I know mine has that 25 years old 'looseness' to it.

I'd start with the conections under the hood, make sure they're clean and solid. I don't have a diagram for the internal column/switch arm but my bet would be worn contacts at the switch.
Considering storage/moisture/corrosion and the relative 'light duty' nature of the wiper switch.

 

[Zero_cool]

Yea I had the same thing with mine. But when they quit working i could turn the switch off and back on and they would work again.
I checked the arms and they look good.
Already cleaned all electrical connections when i bought the truck , but i cleaned around the wiper motor again just to eliminate that possibility.
I ordered a switch and motor from Champion auto , the motor came in today but was the wrong one.I guess the correct one is discontinued.
Switch comes in Tuesday so if thats not it i will get a motor from junk yard.
I did notice that when i have my tester on one of the hot wires and turn the wipers to high the voltage drops...shouldnt the voltage go up?

 

[Anubis8472]

I would think so.

I can't find a diagram for the way the switch/motor work, so I don't know if it uses a resistor on the switch side to vary speed or if it's on the motor etc.

It could always be a bad ground issue to, or frayed wires in the column.

I found this description on some random truck forum in reference to an 84' chevy setup that might be the same as ours....unfortunately the wiring diagram he posted has expired ......
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Note that the control logic for the wiper is GROUND and power is Constant "HOT IN RUN " . Each of the wires 1 pink, 2 PPL, 3 Gray run between the switch and the motor direct, the ground for these is selected by the switch center wiper, (Black wire) Each gives a different speed, high/MED/LOW..

4 LT BLUE and 5 WHT, are the Washer motor, 6 Gray and 7 white are the wiper motor.

Check the Wires for continuity through the system, also you can ground wires 1,2,and 3 one at a time and when you remove the ground, it should cycle one time and park.

If not check to be sure the motor body has a good ground..If all that checks out, The Park switch internal the motor may be broken or out of adjustment as Techin~Tool mentioned.
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I've also found some discussion about wiggling the connector at the motor, often a solder joint in the motor can deteriorate. Though this is in reference to later year models and may not relate to ours.

 

[Zero_cool]

I didnt check the ground wire but i did OHM all the other wires and got zero on all.
Ill check ground tomorrow , and try to ground thos wires and see if the wipers move.
The motor is just ground by the bracket holding the suppressors in place right?
Is there a way to repair the park switch it-self or would i have to get a whole new pump?
Thanks for the help and more so for the explanation on how it works.