Windshield Wiper Motor Problems

Your car wiper motor can fail at any time. To troubleshoot it correctly, you need to understand the reasons for failure as well as the components that are prone to specific problems. Below are some of the most common reasons for wiper motor problems.

Electrical Faults

These include broken or frayed wires, clogged or loose connectors, and bad relay or blown fuse. It could also be a faulty wiper switch or wiper motor control module. Every component of the wiper motor wiring system performs a specific role. When it goes bad, the motor will not receive power. That leads to the wiper motor not working and the wiper system failing.

Clogging

The wiper motor assembly is usually a well-sealed unit. However, it inevitably accumulates dirt over time. A buildup of dirt in the motor assembly or gearbox is one of the common causes of wiper motor problems. It causes the motor to slow down and may also accelerate the rate of wear and reduce the component’s lifespan.

Parts Wear

Being a mechanical component, the wiper motor assembly is prone to wear after operating for a long period. The moving parts eventually wear out, causing problems such as noise and rough rotation. When that happens, the motor has neared its lifespan end and needs replacing or you can change the worn parts such as gears. Some people also rebuild the motor assembly.

Breakage

Apart from wear, wiper motor parts may break and stop functioning. These are mostly the plastic parts such as gears. Broken components cause the wiper motor mechanism to malfunction or stop working altogether. While some parts are replaceable, a broken part can mean replacing the entire wiper motor.

How to tell if a Wiper Motor is bad: Common Bad Wiper Motor Symptoms

Windshield wiper motor problems cause different symptoms. Using these signs, you can easily diagnose your failing car wipers and decide the best way to correct the problem. Here is how to tell if a windshield wiper motor is bad by observing the signs. Common symptoms include those stated below.

Slow Windshield Wipers

The wipers are unusually slow. This is mostly caused by clogged components of the wiper system. It could be the wiper linkages or the wiper motor mechanism parts. Other causes include faulty electrical components such as wires and connectors that lead to a low current in the wiper motor wiring system. Remedies include cleaning the wipers or wiper motor parts. If the problem is electrical, find and replace the affected part.

Wipers Cannot Change Speed

You’re unable to change the speed of the wipers. Reasons for that include the wiper switch not working correctly or faulty wiper control module. These are parts that are involved in controlling the speed settings of the wipers. A faulty wiper switch can be repaired and a control module can be changed. But being electrical, these parts usually require a professional to troubleshoot.

Windshield Wipers not Working

The wipers stop working and you cannot clean the windshield. That often happens when the motor has burned out. It can also be an electric problem within the wiper motor wiring system. Windshield wipers won’t work if a relay is bad, fuse blown, connector loosened, or wire broken. It problem can also be jammed or broken wiper linkage parts. Depending on the type of problem, you can either change the bad part or replace the wiper motor.

Wipers Will not Park in the Home Position

Your car wipers stop in the wrong place when you power them off. This is normally caused by a faulty park switch. The switch is most likely worn or clogged with dirty and not conducting current as it should. A faulty ECU is also another reason why windshield wipers stop in the wrong position. This problem is usually corrected by opening the gearbox and cleaning the park limit switch or replacing the faulty part.

Wiper Motor Noise

There is audible grinding noise coming from the wiper motor. A noisy wiper motor indicates worn or broken parts. If the wiper motor noise is a clunking sound, it may not be coming from the motor itself but the wiper linkages. Most probably, the wiper pivot nuts are loose. It could also be other loose or broken parts. A noisy wiper can be corrected by tightening or replacing the faulty parts. If you have a worn or broken wiper motor assembly, it most likely requires replacing.

How to Test a Wiper Motor

Bad wiper motor symptoms are good pointers that your car wipes are failing. However, they do not help you to rule out other parts of the system such as wiper linkage, arms, and wiper blades. For a complete diagnosis, it’s recommended to test the motor itself. Here is how to diagnose windshield wiper motor using a multimeter.

Step 1: locate the wiper motor. It will be mounted to the firewall on most cars or you can refer to your car manual for the exact location.

Step 2: remove the wiper motor connector

Step 3: identify the negative pin on the connector (upper left) and the positive pin (lower middle)

Step 4: set the multimeter to measure voltage

Step 5: connect the multimeter probes to the respective pins on the wiper motor connector

Check the multimeter readings. If it indicates around 12 volts, the motor is receiving power and is most likely burned out. If there’s not voltage, the problem is upstream. It could be a blown fuse or the relay is bad.