If you’re not a car person, you might not realize just how complex modern automobiles are. This even applies to windshield wiper systems, which can malfunction for several reasons. One of the most alarming and unexpected issues is when the windshield wipers keep wiping, even when turned off. If your wipers refuse to quit, regardless of the position of the wiper switch control, there are a few possible causes. Learn why this may be happening so you can take the right steps to fix it.

How the Wiper System Works

Modern windshield wiper assemblies have several parts: the wiper switch, electronic wiper motor, linkage assembly, two wiper arms and washer fluid tank.

When you flip the wiper switch on, it activates a small electric motor, which spins and moves the linkage assembly. The linkage assembly converts the rotational movement of the motor into side-to-side movement of the wiper blades in their familiar arced pattern over the windshield.

When you turn the wiper switch “off,” it activates a mechanism in the motor called the park switch, stopping the flow of power to the linkage assembly and wiper arms once the wipers return to the bottom position.

Why Wiper Blades Won’t Turn Off

If your wipers keep working even after you’ve switched them off, it’s probably one of the following three problems. The only way to know where the issue comes from is by trial and error replacement of parts, so you might as well start with the easiest one first:

Faulty Relay: Every windshield wiper system has an internal electric switch mechanism called a relay. Automotive relays are small plastic boxes that plug into a particular location in a covered panel underneath the hood near a handful of other relays. A failed relay can mean the wipers won’t work at all, or they may continue to work even when turned off. Changing the wiper relay is the easiest approach and it might solve your problem. Wiper relays usually cost less than $20.

Faulty Switch: This is the switch that’s activated when you turn the wipers on and off, and it has lots of complex internal circuitry inside. Sometimes one or more of these circuits fails in a way that causes the wipers to stay on, often in low or intermittent mode. Changing the switch will be more challenging than replacing the relay because you’ll need to take part of the steering column apart. Look for online videos about this particular operation for your make, model and year of vehicle.

Faulty Park Switch: When the park switch fails, the system no longer tells the wipers to stop at the bottom of the windshield, and they often won’t stop at all. Many systems include park switches built right into wiper motors, so the whole motor needs to be replaced in that case.

How to Fix Wipers That Won’t Turn Off

Fixing wipers that won’t turn off almost always involves replacement of the malfunctioning part. Luckily, it’s pretty easy to find replacement parts online. So once you’ve determined why your windshield wipers won’t turn off, you’ll know what to buy. The job of replacing the part is often simple enough to do at home, but if you’re not confident pulling parts out of your car or aren’t sure what the problem is, consider taking your car to a mechanic.