1999 BMW 540i Sunroof Motor Replacement Cost

Electric sunroofs are fantastic, there is no doubt about that. However, as many owners have found all too clear, they can quickly become a nightmare. If the sunroof motor fails while the sunroof is in the open position, there is little that can be done if the manufacturer did not include a method to close the sunroof manually. The sunroof motor is tucked away under the headliner, attached to the sunroof regulator assembly, and causes the sunroof to open and close when power is directed to the motor. The sunroof motor acts directly upon the sunroof regulator assembly, which holds and moves the sunroof glass and frame. For power sunroofs, the sunroof motor can be thought of as a window regulator motor on the ceiling.

The ability to move the sunroof in two directions is granted by the sunroof motor and sunroof motor switch, which is used by the driver to operate the sunroof. The sunroof motor can have one of several electrical configurations, and these configurations will depend on the type of circuit it uses to reverse directions, as well as the type of external control the sunroof motor will have via sensors and switches. Generally speaking, a sunroof motor will receive power and ground in either wire, depending on which way the switch is pressed. One direction will be the opposite of the other direction. However, there are many variables. A sensor that acknowledges undue resistance while closing the sunroof can alert the body control module to reverse the polarity of the sunroof so it slides backwards. The sunroof position sensor can cause power to the sunroof to immediately cancel, so the sunroof motor cannot move in that direction at all. It is important to understand that older sunroofs work strictly by electrical current from a switch, while modern vehicle's control the sunroof motor by a computerized control module.

A failed sunroof motor will only do one thing - prevent the sunroof from moving. If there is a failure in the sunroof motor, expect the sunroof switch to seem inoperable, and prepare for water intrusion into the vehicle.