Diagnosis On Bi-Xenon Headlights
WARNING: This page does not describe the selected car, but rather 46 other vehicles, including the 2008 BMW M5, 2008 BMW 650i, 2007 BMW Z4, 2007 BMW M6, and 2007 BMW M5. However, it is still accessible from the selected car via links, so may be relevant.
The light module (LM, footwell module on the E90) checks whether or not current flows to the xenon bulb of the bi-xenon headlights when the dipped headlights are switched on. If no current flows, the light module will recognise a fault (fault memory entry).