One problem related to fog light switch has been reported for the 2004 BMW 325. The most recently reported issues are listed below.
Hid (xenon) headlights very dim. Can barely tell they are on when driving at night. (the fog lights are much brighter than the headlights). Creates a dangerous situation when driving at night. Headlight assemblies manufactured by zkw. The reflective material deteriorates inside the headlight assembly leading to very poor light output. Issue has been reported over and over. I guess it's not important enough until somebody dies because of the issue, that is if that hasn't already happened. . . . The ridiculous cost of fixing the issue compounds the problem. Sorry I don't have an extra $2,000. 00 laying around to replace my defective headlights. Come on BMW step up to the plate and fix the problem you're very well aware of, please.