Some Problems You May Come Across with BMW 540i Window Regulator
Whenever you wish to let fresh air in through your BMW 540i's windows, the window regulator should always be there to do the job. And although it generally works fine, it is not a surprise to encounter a few setbacks eventually. Here are some common problems you may encounter with a BMW 540i window regulator.
Windows slowly open or close or won't open or close at all
Over time, the power window switches can accumulate dirt and affect the contacts. When you try to open or close your windows and they move rather slower than normal, the culprit could be some amount of dirt buildup in the contacts. They hold back the electricity needed by the regulator. If the windows don't open or close, the same principle can be applied. When the regulator does not work at all, it could be because of the intrusion of a substantial amount of dirt that has accumulated in the switch's contacts.
In other cases where the windows open or close irregularly, the problem may lie in the cables that are located inside the door panels. These cables connect the motor and the window regulator, but they can slip off from their pulleys. When this happens, the window may travel up or down a couple of inches or they can get stuck in one position, signaling a broken cable. You had better take off the door panel carefully, and examine the window regulator to know for sure.
The next time you try using the switch on your BMW 540i window regulator and it doesn't work, try all the other switches as well. If all of them don't function, a possible cause would be a busted or blown fuse. Check the fuse to confirm if it is busted. You can find the fuse box in the trunk near the battery.
If you experienced changing window regulators more than once in just a year, the problem may lie in misaligned or overly tight window glass tracks. This situation can cause too much stress in the window regulator that results in motor burn up. Another possible cause is having worn or out-of-adjustment glass gaskets. When water enters through the leaking gaskets and soak the window regulator motors, it can also cause them to burn up.