Having some weird electrical problems. The back up lights are not working. The interior panel lights (speedo) dim sometimes. The trip computer went into 24hr mode and then back.
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1994 BMW 540i Question: Brand new battery dies if left for 24 hours. What could be draining the battery?
Answer #1Avery Automotive from Avery Automotive Repair and Towing, July 31, 2013, 08:33Technician
I would start by checked all the doors and trunk to make sure lights are off. Might have a big short somewhere making battery draw. Would take to a repair shop and they can install a meter to battery and start removing fuses to see what is making draw
Reply540guy, August 02, 2013, 00:14Rookie
It turned out to be something that took a master BMW mechanic 2 days to find. After pulling the primary fuse box and the secondary fuse box and going thru all the relays there was still a big draw. It seems that even though it was still functional one of the seat motors was in the constant "on" position. We have a combined 50 years of experience working on BMWs and neither of us had ever seen that. Replace the seat motor and problem solved.
you have a constant pwr draw, have it ck'd out
Reply540guy, August 02, 2013, 00:15Rookie
Turned out to be (after 20 hours of work) a shorted out seat motor. It worked but was alway in the "on" position. Thanks for your input.