In order to test a windshield wiper motor, the first thing to do is to make sure that the motor is getting voltage. Use a digital multi-meter to test a windshield wiper motor's voltage with help from an auto mechanic in this free video on windshield wipers.
How to test a windshield wipe motor. If your windshield wipers are acting up or not working at all then there is a couple of things you can check. If the wiper motor is not working at all then the first thing you'll want to do is check to make sure that you are getting voltage at the motor. Now different vehicles have different wiring schematics so you'll want to check to see what the wiring schematic is like on your particular vehicle. In the case of this vehicle our wiper motor is mounted right here on the fire wall. It has got a connector with multiple wires going in and if we remove that connector I know that the ground pin is the upper left pin and the 12 volt positive for when the wipers are on the regular position is the lower middle pin. So 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 pin and we're getting 11.88 volts which is pretty darn close to 12 volts so we know that we're getting voltage up to the motor. There is a good indication that this motor is likely not functioning. It could be that it just needs to be lubricated, the gear box is full of grease and the grease hardens over time so occasionally you can remove the plant from this, clean out the old grease, refill it with a good multi purpose grease or a white Lithium grease and that might be all it takes. It might 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 and 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 wiper motors are grounded through their mounting bolts and if that's the case you want to make sure that you have a good solid continuity between the mounting bracket of the motor and the chastity 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 with your multimeter simply switch it to resistance or ohms, put one lead on the chastity and one lead on the wiper motor and you should get good continuity between the two. Now this particular vehicle has a separate ground wire so it doesn't need that but that's just something to bear in mind if you are having trouble with a ground related issue on your wiper motor.