1994 Mercedes-Benz S420 Windshield Wiper Motor Replacement Cost

When the windshield wipers are activated, the windshield wiper motor must turn to move a rod back and forth very quickly to move the windshield wipers across the windshield

When the windshield wipers are activated, the switch sends a signal through the fuse, and possibly a relay, and power reaches the windshield wiper motors from one of two paths. When it reaches the windshield wiper motor, the motor will being moving a rod back and forth as quickly as the driver has selected. The rod is attached to the windshield wiper arms, and forces the arms to move in unison with the driven rod. When the rod pushes the arms across the windshield, the wiper blades remove moisture and contaminants from the glass.

A failed windshield wiper motor will do one of two things in the event of failure. First, it can intermittently work, meaning when the wiper switch is turned on, the windshield wipers may activate, and run for a random amount of time. This may happen at random, or change with a bump. Lastly, the windshield wipers could show no signs of activity, indicating motor failure.

Driving without windshield cleaning components is not typically considered unsafe, but there will be no system to properly clean your field of vision if the need arises. If the windshield cleaning system is heavily relied upon in your location, consider repairing the system sooner than later.

This is not a frequently failing component. The majority of vehicles with windshield wiper motor failure are much older. The frequency of use is an important factor, but most often they have very low expectation of failure, just as they have very low expectation of long periods of extended use.

Windshield wiper motors are diagnosed by a guided process of elimination, from most likely, to least likely. The fuses are checked first, then the power at the windshield wiper switch, then power coming from the switch, to the wiper motor. If there is electrical power going to the windshield wiper switch, but the switch will not send power to the windshield wiper motor, the switch or wiring must be replaced. If the switch sends power, but the windshield wiper motor will not run, power at the windshield wiper motor would be checked. If electrical power reached the windshield wiper motor, but the motor did not run, it would be bench-tested, and confirmed failed.

To replace the windshield wiper motor, access to the front cowl/rain gutter is necessary, which means the technician will have to remove the windshield wiper arms, plastic covers, and any lower that converge with the windshield seal. Once access is gained, the servicing technician will being disconnecting the windshield wiper motor from the windshield wiper are linkages/rods. The windshield wiper motor is able to lift out once disconnected. Installation is the reverse of removal, and the wiper arms, and wiper blades should be inspected for condition, and function.

Windshield wiper motors for the most common vehicles are typically available from the aftermarket at a discount from the manufacturer price, but should be guaranteed to meet or exceed OEM standards if used. Many low-production, specialty, or luxury vehicles may require the windshield wiper motor to be purchased from the dealership, as the aftermarket may not invest in reproduction of parts for specific applications.

In most cases, a technician will charge a diagnostics fee for testing the system, and determining the wiper motor is faulty. This protects the customer from needlessly replacing a properly functioning component.

When the windshield wipers stop clearing the windshield, you may decide to replace the motor at home. This can be done without too much complication, and just a few hand-tools. The motor is normally tucked away underneath the cowl, but there is always a way to gain access. If you cannot gain access, or figure out how to get the motor out of the vehicle, take the vehicle to a professional technician to ensure the job is completed correctly.