Windshield washer pump: how it works, symptoms, problems, testing
In modern cars, the windshield washer pump comes as one unit with a small electric motor. Typically, the windshield washer pump is installed in the lower portion of the windshield washer fluid tank (bottle).
Windshield washer pump (motor) is located at the bottom of the windshield washer fluid tank.
In most cars, the windshield washer tank is located behind the front bumper, in front of one of the front wheels; see the illustration.
How it works: When you operate the washer with the switch, it sends the signal to the control module (e.g. BCM) that, through the relay, operates the windshield washer pump. The pump pumps the windshield washer fluid through the hoses that are connected to the washer jets.
Windshield washer pump problems
One of the common problems is when the windshield washer pump electric motor fails and doesn't run when activated by the switch. In some cases, the pump fails, so you can hear the motor running when the washer switch is operated, but the washer fluid doesn't spray. A bad windshield washer pump (motor) must be replaced.
There are several other problems that can also cause the windshield washers not to work. For example, corrosion at the washer pump electrical connector or problems with the electrical circuit can also cause the pump not to work. Not all problems with the windshield washers are caused by issues with the washer pump. For example, a leaking or pinched fluid hose can also cause the washers not to work even when the washer pump is running. The symptom of a disconnected hose is the washer fluid leaking somewhere under the car when the washer pump is operated. Due to its location, the washer fluid tank is also prone to damage or cracks that can cause the fluid to leak out. Another common problem in below-freezing temperatures is when the fluid in the washer tank freezes, read more below.
Windshield washer pump replacement
Replacing the windshield washer pump (motor) is not very difficult if there is good access to its location. In most cars, it just pops into the rubber sleeve installed at the bottle. The key to replacing the pump is to remove it carefully without damaging the rubber sleeve. If the rubber sleeve is dry, spraying a silicone lubricant will help.
Windshield washer pump (motor).
The new windshield washer pump (motor) costs from $15 to $35. A repair shop may charge you $50-$150 labor to replace it. The diagnostic fee is usually separate.
The windshield washer fluid freezes in cold temperatures
This happens when the summer windshield washer fluid is left in the washer fluid bottle. When the temperature drops, the summer fluid freezes. The solution is to bring the car inside a warm garage and let the ice melt. It may take several hours. Some people pour warm water on the sides of windshield washer bottle to melt the ice in it. Once the fluid melts and the washer pump starts working, use up the old fluid and refill the bottle with the winter-grade windshield washer fluid. The fluid can freeze not only in the bottle, but in the hoses and in the washer jets as well.
How the windshield washer pump (motor) is tested
When you press the washer switch, the pump (motor) is powered by the 12 Volt battery power. It only works when the ignition is ON or when the engine is running. If you don't hear the washer pump running when operating the washer switch, the first step is to check the fuse. You can find the location of the fuse on the fuse box cover or in the owner's manual.
When the switch is operated, there is no voltage at the motor
Windshield washer pump/motor basic wiring diagram
If there is no or low voltage at the pump when the switch is activated, the electric circuit must be checked. The washer pump (motor) circuit is simple: The multifunction switch sends the signal to the body control module or BCM. In some cars, the control module might have a different name, for example, in some Hondas it's called MICU. The control module supplies the 12 Volt power to the relay or directly to the pump (motor).
If there is no power at the motor, the voltage must be checked at the connector at the control module.
There could also be another connector between the windshield washer motor and the control module. Since in many cars, it is located behind the front bumper or in the wheel well, it is prone to corrosion damage. If there is no power at the control module, the power at the switch must be checked. The switch operation can also be checked with a scan tool that can access the BCM.
The ground terminal is another important point that must be checked. A loose or corroded ground terminal is one of the most common reasons for many hard-to-diagnose electrical problems.
If you need a proper electrical diagram for your car, read more: How to find an owner's or service manual for your car online.