The weight of heavy snows and slush can put a lot of pressure on a windshield wiper motor and cause them to wear out. When the motor wears out the wipers will stop working. Your mechanic can inspect the motor to make sure you don't have any other problems (like a bad fuse or electrical connection) that could cause the motor to stop working. Here is how a mechanic will determine if the motor is bad and how they can replace it.
Inspecting Windshield Wiper Motor
The windshield wiper motor is placed underneath the grille at the bottom of the windshield. The mechanic will unscrew the grille from the grille bracket and remove it to gain access to the motor and the electrical connection harness.
The mechanic will disconnect the electrical connection harness and attach a multimeter to the positive wire in the connection. The positive prong on the multimeter is colored red. The multimeter will also have a black prong. The black prong is connected to a ground wire – which is normally colored black. The multimeter will be set to the DC (direct current) mode. The ignition switch in the car is turned to the accessories setting. The accessories setting restores the flow of electricity throughout the wiper system. If the multimeter gives off a reading, then the mechanic knows that there is electricity flowing to the motor.
The switch on the electrical harness will also be checked. The red prong is attached to the purple wire in the electric harness and the meter will be set to the "Ohms" position. The Ohms position measures resistance in the electrical circuitry. Resistance means there is something blocking the flow of electricity through the switch. The windshield wiper switch in the car is set to the highest speed. If the meter shows little to no resistance, then the switch is working fine and the mechanic will replace the windshield wiper motor.
Replacing the Motor
The windshield wiper arm is detached from the shaft on the motor. This is done by lifting the cover on the base of the wiper arm to expose the nut holding the arm to the shaft of the motor. The nut is removed and the arm should lift up off of the shaft. Sometimes it has to be wiggled a little bit before it will loosen so it can be pulled up off of the shaft.
There are normally four bolts holding the motor to the motor brackets. The bolts are removed and the motor is taken out from underneath the grille bracket. The mechanic will compare the old motor to the new one to make sure the bolt holes are configured the same on both parts. Then the mechanic will slide the new motor underneath the grille bracket and bolt it into place. The electrical harness and wiper arm are reconnected to the motor. The mechanic will turn on the car and test the wiper motor to make sure it works well before the grille is screwed back into place to finish the job. Contact a mechanic, such as Newton Tire Company, for more help.