What Is a Wiper Relay Switch?by Richard Asmus
Safety and control of your car or truck depend on your windshield wiper systems. They run at various speeds, with an option to spray water with a cleaning solution for bugs and mud.
Wiper Relay Switch
Although many vehicles do not have them, a wiper relay switch operates when you turn on the wipers. It closes contacts that provide voltage to the windshield wiper motor.
In some vehicles, the wiper relay switch is inside the actual windshield wiper motor. If it fails, the entire motor needs to be replaced, as you can't get parts to fix it.
Second Wiper System
Some vehicles have a second wiper on the rear window. This wiper could be controlled by a wiper relay switch.
Many wiper motors don't need much current to run. Their wiper controls connect directly to the wiper motor without a relay.
The washer systems associated with your windshield wiper control switch usually doesn't need a relay. It wires direct from the control to the pump.
Intermittant Wiper Relay
Some intermittent windshield wiper systems use a relay controlled by a timer. These relays may be inside the actual windshield wiper motor also.
Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. After founding a small telecommunications engineering corporation and visiting 37 countries, Asmus studied broadcasting at Arizona State University and earned his Master of Fine Arts at Brooklyn College in New York.