LM: Light Module
WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.
The light module (LM) controls and monitors all vehicle lights. Information is received and transmitted via the K-CAN data bus (body controller-area network).
The light module (LM) provides the terminal 58g signal via the K-CAN. The LM also transmits the dimmer signal to the head-up display.