85 silverado. it does have delay wipe, fast and slow. if I turn them on with a dry windshield they turn super slow. if the windshield is wet it works better. After 2 minutes of constant running,(wet or dry) its like it heats up and moves real slow then comes to a stop. Once it cools off it works again, but in the same pattern LOL. I even used a external toggle on/off switch with same results.
Whats my first move to resolve this matter? Thanks
Didn't we work on this same issue a few years ago? IIRC you were going to get a new motor.
Anyway, first check is for a mechanical overload condition. While doing these steps, keep in mind that this advice is all very subjective:
1. Just get the wiper blades off the glass. Do this by pulling the arms forward into the locked position. Then run the wipers and note any increase in speed.
2. If the motor still heats up and slows down, the next step is to completely disconnect it from the linkage/arm drives and observe shaft speed.
Just release the three mounting screws, and gently pull the motor away from the firewall. There is sufficient flex in the wiper linkage to do this. You will see a crank arm with a ball on it that connects to the linkage - leave that (ball joint) connection alone.
The other end of the arm is secured to the motor shaft with a nut. That nut can be released (and the crank pulled off the shaft) by inserting a wrench between the firewall and the
wiper motor frame and onto the nut. That is how I disconnect the arm from the shaft.
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The service manual procedure is to use the hole provided (32 below) to release the nut. Problem is, it is offset quite a bit from the connection. That makes it hard enough. But also, more often than not, I drop the nut down into the depths of the plenum and have to spend a couple of hours fishing it out.
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NOTE: When you go to reassemble the crank on the motor shaft be SURE that they are indexed to each other correctly. By that I mean, it is important that both the motor and wiper arms are in the fully parked position.
The crank arm can go on the shaft in 2 different positions. If the arm is 180 degrees off from the normal angle, it will suck.
When you operate the wipers, the blades/wiper arms will work beautifully - except for the fact that they will park at the top of the windshield. You will have to release the coupling and do the job again.
The wiper arms are easy - just push them down to a point where the blades are almost touching the windshield gasket.
To preset the motor to park position, just plug in the wiring harness connections, turn the switch on and run it for a couple of revolutions. Turn the wiper motor off at the switch and then mate the motor shaft to the crank arm.
It might sound wicked involved, but everything will become obvious as you do the replacement.
So, assuming you didn't find any evidence of a mechanical problem, next thing is to eliminate the
pulse module as the problem by removing it from the circuit. The module is designed to be plugged into a non-intermittent circuit using the existing connectors. Just unplug the module on either side and then reconnect the two harness connectors. So instead of this:
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You'll end up with this:
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Run the wipers with the module removed and see what you've got.
If, after these steps - you're still having trouble - it's down to wiring/terminal condition or a motor that's just old and tired.
I doubt it is a grounding issue because the ground lead from basically every electrical component in the cab is spliced together. There is just one wire that runs from the splice to the common bus block. You'd have a lot more problems.
