QuestionMy wipers don't work. How can I test to see if it is the switch or the motor? I appreciate any help you can give me.
Answer I wrote a long response to this, and the system lost it somehow - OK, second try - I'll be brief this time!
You can test it by applying 12 volts to the RUN wire at the motor, but since they seldom fail, try this first:
At the fuse box, find the wiper fuse, and using a voltmeter or a test light, verify that there is 12 volts at both ends of the fuse, AND ON THE CLIPS THAT HOLD THE FUSE AT BOTH ENDS!!! It is very common on old cars that the fuses build up a layer of insulating crud on the end caps that prevents them from making contact with the end clips, even though everything looks great visually.
The wiper fuse should have power any time the key is on.
If you have 12 volts that far, then check at the back of the wiper switch. There should be one wire that has 12 volts all the time when the key is on - that is the wire that comes from the fuse clip. There should be another wire that has 12 volts when the key is on, and the wiper control is "OFF" - that is the "PARK" wire. There should be a third wire which has 12 volts only when the key is on and the wiper control is on the "ON" position. This is the wire you need to identify by noting the color. Find this wire at the wiper motor, and apply 12 volts directly to the wire at the motor - it should start running - if it does not, the motor is suspect.
Back to the switch - if you don't find 12 volts on the run wire when the key and the wiper control are both on, but you do have 12 volts on the wire from the fuse, the switch is bad.
My money is on the fuse clips, by the way. Clean them with fine sandpaper or crocus cloth - if you use sandpaper, be sure to blow the grit away when you are done.
Dick
