The windshield washer pump is a pump driven by a small electric motor. It is usually found attached to the washer fluid reservoir, whose location can vary depending on the vehicle but can usually be found near the radiator. Occasionally, the washer pump is found connected to the wiper motor, which is located below the windshield wipers under a cowl.

If you drive on dirt roads or live somewhere that sees plenty of road salt, then you’re probably familiar with your windshield washer pump's purpose. The washer pump is responsible for pumping washer fluid from the windshield washer reservoir, which stores the fluid. From there, it goes through hoses to the washer nozzles that spray the fluid onto the windshield. Then, thanks to the wiper blades (and the numerous other parts of the wiper system that connect to and power the movement of the blades) that “wipe” the fluid all over your windshield, you are able to wash the dirt and gunk off of your windshield and clean it. This is not only convenient in how it lets you clean your windshield without having to stop and squeegee it off at every gas station along your trip, but also essential in how it maintains your visibility for avoiding road hazards. 

The entire process is put into motion via the vehicle’s windshield wiper switch, which is located on the side of the steering column. The switch activates the windshield washer pump, which pumps the washer fluid from the reservoir to the washer nozzles, and the movement of the vehicle’s wipers. All of this allows you to maintain a clean windshield and a clear line of vision while you drive. Many of these are multi-function levers that also include dials and switches to activate other systems—like fog lights, for example. The lever connects to a switch inside the steering column that contains the circuitry that sends the driver’s input to the wiper motor and washer pump. Some assemblies combine the lever and switch into one unit.

Some SUVs, vans, and wagons also have rear window wipers and a rear window washer pump.  Frequently, in these systems, one washer fluid reservoir is used, with two pumps attached to it.

If you activate the windshield washer and no fluid sprays out, or the spray is weak, then it might be time to start thinking about replacing your windshield washer pump. There are other problems which can inhibit the flow of washer fluid, so it may be best to check the whole washer system. Make sure that the nozzles aren’t clogged and that the hoses aren’t crimped, leaking, or blocked. Make sure that the washer fluid reservoir is full and not leaking. One way to isolate the washer pump as the source of the problem is to try to run it with the car or truck on but the engine off. This will allow you to hear whether or not the windshield washer pump motor is working. If the washer pump motor isn’t running, you could use a voltmeter to check that it is receiving current. If you're getting proper voltage to the pump when the windshield wiper switch is activated but no fluid is flowing through the system, it’s time to replace your washer pump.

There are a number of factors that can contribute to washer pump failure. Over time, the seals inside the pump can dry out and cause the pressure to drop and not allow a proper spray. They can also seize and fail if run without washer fluid too often. Using water rather than washer fluid can also damage internal pump parts. The water may freeze and expand in cold weather, damaging the pump. It’s also possible to burn out the windshield washer pump motor through very frequent use. This unfortunately means that the drivers who most need a working washer pump are more likely to have a broken one.  Trying to run the pump without wiper fluid can also burn out the washer motor. A car accident may also rattle the windshield washer fluid pump and damage its internal components. 

Fortunately, getting your windshield wiper pump back in working condition should be within the reach of a do-it-yourselfer. You will most likely have to remove the washer fluid reservoir. Assuming your reservoir is in good condition, you’ll just have to attach the new pump to the reservoir and reinstall the reservoir.