What year E 38,Do you have the push-in breakers, or the flip type. Is all your 12 volt stuff down or just certain ones? Cold be a loose wire on the 12 V buss,Bad ground. Isolate the systems that are inop, take your panel looseand see if they are tied together. also see if there is a master breaker between the batteries and the panel. You have a lot of options, depending on how it may be wired, AFTER it left the factory. the more info you have, the eassier it will be to isolate the problem. Good luck, Harold