How to Troubleshoot a Windshield Wiper Motorby Dan Ferrell
Windshield motors come with varied features depending on manufacturer and car model. Some motors have three speeds, others include an integrated interval mode for light and fine misty rain and still others come with reverse to set the wipers under the hoodline. They are all very convenient functions, but a car’s windshield with a broken wiper motor under heavy rain is just as good as a vehicle without brakes. If you have a basic knowledge of electricity or have the patience and like a challenge you can learn the general procedure to troubleshoot a wiper motor.
Make sure the battery has a strong charge and is in good condition. Use a voltmeter to get a reading if necessary.
Connect a jumper wire between ground and the wiper motor. Turn the key on but don’t start the engine. Turn the wiper switch on. If the motor works, check for a corroded or loose ground connection.
Turn on the car key but don’t start the engine. Turn on the wipers. Check for voltage at the wiper motor with your voltmeter. If you get a good voltage reading, turn the key off and disconnect the motor from the wiper linkage.
Move the wiper arms by hand. If they are stuck, you have found the problem. If the wiper arms move freely by hand, go to step 5. If voltage is not reaching the motor go to step 6.
Remove the wiper motor by disconnecting the plug and removing the bolts using a wrench or ratchet. Use a pair of jumper wires to connect the wiper motor directly to the battery. If the motor does not work, replace it.
Turn on the key but don’t start the engine. Get a voltage reading across the wiper switch. If there is voltage, use a jumper wire to bypass the switch, if the motor works now, replace the switch, otherwise go to step 7. If there is no voltage at the switch, go to step 8.
Check for continuity at the wire between the switch and the motor. The wire could be loose or disconnected.
Check the wire coming from the fuse panel to the wiper switch. It could be disconnected or loose.
- Before beginning any troubleshooting test on any car electrical system, always make sure that the particular circuit’s fuse or breaker is in operating condition. Many problems originate at this point and are very often overlooked.
- It is a good idea to have the wiper motor wiring diagram on hand for your particular vehicle whenever you are troubleshooting its circuit. Most vehicle service manuals come with wiring diagrams for the different electrical systems.