On a vehicle there is only one motor for both windshield wipers.
One of the wipers such as on the drivers side is connected to the motor and then a link or rod connects the other wiper.
The wiper motor turns and operates both windshield wiper motors at the same time.
When a wiper motor is going bad it will usually start stopping and starting or simply stop working when you have the wipers on.
Sometimes you can get the wiper motor to work again by moving the wipers back and forth by hand.
In some cases it may be a loose connection to the wiper motor.
A wiper motor can be easily replaced and is often located on the drivers side of the vehicle.
You can buy a new wiper motor for around $50.00 to $150.00 depending on the vehicle.
If you have a shop replace the new wiper motor it can cost around $100.00 to $150.00 for labor charges and the wiper motor.
So having a shop replace the wiper motor can cost around $150.00 to $250.00 to $300.00 for parts and labor.