Windows go down by themselves; interior lights stay on. The Fix: The ZKE schematic shows the General Module III (GM3) is the brain. It sits under the passenger carpet. Water from clogged sunroof drains kills this module. Pull the module, open the schematics, and resolder the dry joints on the connector pins (X253 and X254).
The BMW 5 Series (E39), produced between 1995 and 2003, is widely regarded as one of the most robust and driver-focused vehicles BMW ever produced. From the inline-six brilliance of the 528i to the V8 muscle of the 540i and the legendary M5, the E39 is a modern classic. However, as these cars age, their complex electrical systems become a primary source of headaches for owners.
