It’s a nice sunny day and you’re driving across the highway. However, your car’s windshield wipers turn on randomly. Why are the wipers doing that and what can you do about it? We researched these concerns for you and here’s the explanation we found.
Windshield wipers may turn on suddenly if it has an underlying problem. Some possible reasons why this may happen are faulty wiring, a short circuit, or a bad rain sensor. Make sure to troubleshoot the issue first so you can apply the correct solution and fix the problem at its core.
Continue reading as we take a look at the potential causes of why your windshield wipers may activate randomly in greater detail. We’ll also tackle some possible solutions that may help restore your car’s windshield wipers' proper functions.
Why Are My Windshield Wipers Turning On Randomly?
A car’s windshield wipers may turn on erratically for several different reasons. Take note that these instances can occur even without activating the wipers manually. Some possible origins of these occurrences are:
Windshield wiper wiring is often a complicated illustration that typically requires automotive expertise to troubleshoot and repair. This complex array of wires may cross or fray, causing the windshield wipers to turn on and off randomly.
Heavy rains and frequent car washes may cause moisture to enter the windshield wiper assembly, particularly the connections. The wetness may harm the system, making the wipers activate without human interference.
Damaged Park Switch
Take note that a car’s park switch generally functions by turning on the vehicle’s lights as you move the automobile away from a parking site. The parking lights will turn on upon activating this switch while the other lighting fixtures turn off.
However, since this switch is usually at the corner of the cabin, it might cross with the windshield wiper motor. If so, turning on the park switch may also activate the windshield wipers at the same time.
Bad Rain Sensor
Some cars have rain sensors that should activate the windshield wipers if they detect rainfall. These may incorrectly signal the wiper’s control module to function despite driving on a reasonably sunny day.
Body Control Module (BCM) Malfunction
The BCM is the “brain” of the windshield wipers and it works by controlling the assembly through the signals received from the wiper and washer switch. It’s also an electronic module that may encounter bugs, errors, or glitches, triggering the wipers to function at random moments.
How Do You Fix Windshield Wipers That Turn On By Themselves?
In this section, you’ll learn some possible solutions that may help you in restoring the way your windshield wipers should work.
Rewire A Windshield Wiper Motor
You should only take on this project yourself if you have sufficient expertise and skill in working with automotive parts. If not, it might be best to leave it to the experts. But if you're confident and know your way around automotive assemblies, you may wish to continue doing this project.
Also, it can be useful to remove the windshield wiper motor from the vehicle when you need easy access to the system’s wires. Watch the video below if you need assistance with this part:
With the windshield wiper motor and its connected wires removed, search for any cut or frayed wires. If you find any damage there, replace the bad wires with new models.
You can also watch the following video to help you with the rewiring process:
If rewiring didn’t solve the problem, you may need to replace the windshield wiper motor. But make sure that you purchase and install a compatible motor to prevent further problems.
Replace The Rain Sensor
Take note that it’s often best to replace a windshield wiper’s rain sensor if it becomes bad. But as with other automotive repair jobs, be sure to check your owner's manual first before attempting this on your own. Different vehicles will require different methods.
To get an idea of a typical procedure, let's look at an example. These are the steps to replace a BMW’s rain sensor:
What You’ll Need
- Panel remover
- Remove the rearview mirror using the plastic panel remover
- Disconnect all the wires attached to the old rain sensor. You may need to use the screwdriver for this step
- Install the new rain sensor and connect the wiring to it
- Return the rearview mirror assembly
- Turn on the car and splash water on the windshield to check if the new rain sensor works
Tip: Take a picture of the assembly before removing the wires. That way, it should be easier than usual to connect the wires to the new rain-sensing module.
You can also watch the video below to see the steps above with your own eyes:
How Do You Reset Windshield Wipers?
It’s important to note that the steps to reset windshield wipers often depend on the car’s brand and specific model. So read your owner’s manual first to check if you need to go through certain steps to complete this process with minimal risks of errors.
You can also check out these steps to reset windshield wipers on a Ford vehicle to give you an idea of how to do this procedure:
What You’ll Need
- Socket wrench
- Open the hood of the vehicle.
- Locate and remove the wiper’s cover caps using the socket wrench.
- Remove the wiper arm from the windshield. You may need to jiggle or rock the assembly slightly for it to come out of its attachment.
- Repeat steps 2 and 3 for the other wiper arm assembly.
- Turn on the vehicle and let the wiper assembly run for about a minute or two.
- Turn off the wipers, then turn off the engine. That way, the wiper assembly should return to its default resting position.
- Return the wiper blades while following the indicator on the windshield that marks the correct starting point of the assembly.
- Secure the windshield wipers again.
- Turn on the vehicle once more and test if the windshield wipers are now working as intended.
You can also watch the video below if you need a visual guide for the steps mentioned above:
How Much Does A Windshield Wiper Fuse Cost?
Aside from the issues already mentioned, your car's windshield wipers may malfunction if it encounters a fuse failure. If so, you may need to spend approximately $10 to $50 to replace the component.
Can You Replace Windshield Wipers Yourself?
You may replace your car’s windshield wipers without requesting professional help. The process of replacing the wipers is much simpler than replacing the motor.
You need to make sure the replacement wipers are compatible with your vehicle. Choosing the wrong model might create additional problems with your vehicle’s windshield-wiping system.
After buying the correct windshield wipers, you can follow these standard replacement steps:
- Lift the wiper’s arms from the windshield.
- Remove the windshield wiper blades from the arms according to the steps indicated in your vehicle’s owner’s manual.
- Install the new windshield wipers based on the manufacturer’s instructions.
How Do I Know What Windshield Wipers To Get?
Generally, the main factor you need to think about in choosing a replacement windshield wiper blade is its size. You have different tools at your disposal to select and install a correctly sized blade for your car’s windshield wipers. Some solutions are:
- Car’s manual: Many vehicle manufacturers place the appropriate wiper blade size for your car’s specific model.
- Online tools: Certain online portals, such as rainx.com, allow users to check their windshield wiper size requirements based on the vehicle.
- Expert help: Automotive repair shops often have technicians that know the right size for your replacement wiper blades.
Remember to troubleshoot your vehicle's windshield wipers first before attempting to repair these assemblies. Skipping the troubleshooting part may put further harm to the wipers. Once you detect the source of the anomaly, you should be able to apply the correct steps to fix the windshield-wiping system.
Aside from your windshield wipers turning on by themselves, your car might also be experiencing other problems with this assembly. These other posts might help you out with those concerns: