Wipers don't go off. Works on high and low. Sometimes they stop but always come back on. Trying to narrow it down. (Windshield Wiper Motor Relay)

Answer

Jun 12, 2025 - 04:52 PM

If your wipers won't turn off even though they work on high/low, this usually points to one of the following components, common across most vehicles:

1. Wiper Motor Pulse Board / Control Module

Many wiper motors have an internal control board that governs timing and the "park" position.
If this board fails, the motor may keep running even when the switch is off.
Very common failure point, especially in older GM, Ford, and Toyota vehicles.

2. Wiper Switch (Multifunction Switch)

The switch/stalk you use to operate the wipers may send a stuck or faulty signal.
If internal contacts short or wear out, the switch might keep telling the wipers to run.

3. Wiper Relay (if applicable)

Some vehicles use an external relay to control power to the wipers.
If the relay sticks closed, the wipers won’t shut off.
Try removing the wiper relay while they’re stuck on—if they stop, replace the relay.

4. Body Control Module (BCM)

In newer cars, the BCM acts as a middleman between the switch and the motor.
Rarely the issue, but possible if all else checks out.

Now for some basic diagnostic steps applicable to most vehicles:

Unplug the wiper switch (usually at the steering column):
- Wipers stop → the switch is bad.
- Wipers keep running → the problem is in the motor/control board or relay.
Pull the wiper relay (if the vehicle has one):
- If pulling it stops the wipers, try replacing the relay.
Tap the wiper motor housing:
- If it temporarily stops the wipers, the internal board is likely faulty