Wipers stopped working.

[one4fun]

Driving home from Tacoma today, constant downpour all the way to Portland. After a couple hours, the wipers suddenly stopped. I noticed they were going slow on the return sweep before they quit. I pulled over, lifted the wiper arm and they returned to their off position. This happened 3x in about 2 miles. Finally, I ended up turning the wiper on and off after it made one full sweep. About every 10 seconds so it would not freeze up again.
Where do I start to troubleshoot this problem? Wiring? Wiper motor?

 

[chengny]

The following is not a definitive test, but it might help you determine whether the wipers are stalling due to external resistance (e.g. excess play in the linkage) or an internal motor problem:

Note: It is important that before doing this test, all associated electrical connections have been checked (to eliminate loose/oxidized contacts as the problem)

When you have a few minutes, flip the arms out - so the blades are off the glass - and run the wipers (high speed will show results faster). Let them like that run for a while. Do this with the engine running - so a weak battery doesn't enter the equation.

If the wipers run normally for a good long time - with the blades lifted off the glass - it is a good bet that the problem lies with the linkage.

If they stall with the blades off the glass, it is most likely an internal motor problem. But it could still be a linkage issue. To diagnose this further requires that the wiper motor be completely disconnected from the linkage.

Back out the 3 bolts that secure the wiper moor to the firewall. Pull the motor away from the FW, back the motor shaft nut off and release the linkage crank arm from the motor shaft. Bolt the motor casing back to the FW and run the wipers again.

If, with the arm linkage not connected to the motor, the motor continues to stall - it is then a safe assumption that the motor is shot.

 

[89Suburban]

My money is on the motor but here is some info to help diagnose.

http://www.gmsquarebody.com/forum/showthread.php?t=9913&highlight=wiper

http://www.gmsquarebody.com/forum/showthread.php?t=8749&highlight=anatomy