Electric Window Motor - Diagnostic Procedure

91bmw05

Group 51
Body Equipment


Bulletin Number
51 01 91 (3216)


Woodcliff Lake, NJ
March 1991
Service Engineering


SUBJECT: Electric Window Motors

MODELS: 3 Series (E30) - All so Equipped

Situation: An increasing number of window motors (P/N 51 31 1 380 854) returned under warranty are found to be not defective when tested.

Before condemning a window motor as defective, check the motor by holding the "UP" button depressed for approximately 10 seconds, and listen for a "click" from the area of the affected motor.

Note: This "click" can be heard best in a quiet environment (i.e., engine not running, radio & air conditioner off, windows and doors closed). Familiarize yourself with this sound by performing this procedure in a vehicle with known good window motors.

If this motor is continuously powered against a stop (stalled), a thermal protection switch inside the motor will open after approximately 6 seconds. It will reset after approximately 2 seconds. The opening of this switch produces a distinctive "click".

If it is determined that this thermal protection circuit is working properly i.e., if "clicks" from the switch can be heard, the motor is in all probability working properly, but encountering excessive load. The window regulator and window channels should be inspected for binding, distortion, lack of lubrication, etc.

Important Note: Window motors returned under warranty and found to be not defective will be returned to the dealer.
Warranty
Status: Information only.