What is the windshield wiper motor and how does it work?
The windshield wiper motor is a small electric motor. A shaft coming out of the motor connects to a linkage/transmission assembly that converts the rotary shaft movement of the motor to the linear, back-and-forth motion of the wiper arms across the windshield. In addition to the windshield wiper motor in the front, some SUVs, vans, hatchbacks and station wagons have an additional wiper motor mounted in the tailgate to keep the rear window clear.
When to consider replacing the windshield wiper motor?
- No wiper function at all. Windshield wiper motors can fail, but prior to replacing the motor, the mechanic will check its power supply.
- Wipers don’t park in the down position. There is an internal switch in the wiper motor that keeps the motor powered after you have shut it off to ensure the wipers park in the right spot. If that switch fails, the wiper motor must be repaired or replaced.
- Erratic or slow wiper operation. If the electric motor or the transmission have worn excessively, you might experience erratic, intermittent, or slow wiper operation.
- Grinding or clunking noises. Excessive wear in the motor transmission or wiper linkages may cause noise. A mechanic will determine the cause of the noise before performing repairs.
How do mechanics replace the windshield wiper motor?
- Remove the cowl and any covers over the wiper motor and transmission assembly.
- Remove the plug harness to the motor and disconnect the wiper transmission arm from the wiper motor.
- Remove the bolts holding the motor and transmission assembly to the body of the car.
- Install the new motor. The plug harness is usually keyed so it can only be inserted in one direction. If not, the proper polarity must be observed. Bolt the motor to the car body.
- Cycle the motor several times by turning it on and off to establish the park position, then re-attach the linkage transmission assembly to the wiper motor.
- Install all covers, cowling, and so forth and test operation of the motor on a wetted glass only.
Is it safe to drive with a windshield wiper motor problem?
Yes. So long as the weather is clear and there is no rain, snow, or ice, it is safe. However, if the wiper motor is not functioning properly driving in adverse weather conditions is quite risky and may even be impossible in heavy rain, which will often completely obscure your view through the windshield. Due to the unpredictability of the weather, it is always best to have the windshield wiper system in good working order.
When replacing the windshield wiper motor keep in mind:
- Never turn on the wipers if the windshield wiper blades are frozen to the windshield or their path is blocked by snow or ice.
- When the wiper motor is replaced, all the linkages in the wiper system should be lubricated.
- The rubber inserts in the wiper arm have a lifetime of about 1 to 2 years. Replacing the inserts regularly will make it safer to drive in adverse weather.