How to Test a Windshield Wiper Motor

To test a windshield wiper motor is an important part of the maintenance process. If your windshield wipers are acting up or not working at all, there’s a couple of things you can check. If the wiper motor is not working at all, the first thing you’ll want to do is check to make sure that you’re getting voltage at the motor. Different vehicles have different wiring schematics, so you’ll want to check to see what the wiring’s chromatic is like on your particular vehicle. In the case of this vehicle, our wiper motor is mounted right here on the firewall. It’s got a connector with multiple wires going in. If we remove that connector, the ground pin is the upper left pin and the 12 volts positive for when the wipers are on the regular position is the lower middle pin.

I’ve set my digital multimeter to voltage and I’m going to take my probes and I’m going to put the ground probe in on the ground pin and the positive probe on the positive 10. We’re getting 11.88 volts, which is pretty darn close to 12 volts. From that we know that we’re getting voltage up to the motor. There’s a good indication that this motor is likely I’m not functioning and it could be that it just needs to be lubricated. The gearbox is full of grease and the grease hardens over time. So occasionally you can remove the plate and clean out the old grease, then refill it with a good multipurpose grease or white lithium grease. It might also need to be replaced completely. If you’re not getting 12 volts at the connector then you might have a blown fuse.

You might have a problem with the switch, the wiper switch itself, or you might have an issue with the wiring between the switch and the connector. The fuse is obviously the easiest thing to check, then the switch, and then finally tracing the wiring to see if you have a short or an open wire. One last thing to consider is that some white promoters are grounded through their mounting bolts. If that’s the case, you want to make sure that you have good solid continuity between the mounting bracket of the motor and the chassis of the vehicle. If that ground connection is corroded or broken, then it will keep the motor from running. And the easiest way to test that again is like your multimeter. Simply switch it to resistance. Put one lead on the chassis and one lead on the white promoter and you should get good continuity between the two.