santino

I have a battery drain on my 04 E55 . picked this car up last month & ive had the problem since I bought it
car drops from 12.4v to 12.0v after sitting for 1 day, and down to 11.5v after sitting for 2 days.
i do not have keyless go, and i don't leave the key in the ignition

ive spent hours reading through old threads to learn about this issue.
what ive gathered is to first test battery + alt , if those check out, then most threads point to BCM, SAM or voltage regulator as a likely culprit .

i had battery tested & it is fine. its a Bosch battery that looks new. have not had alt tested as it seems to operate fine. voltage with car idling is 13.9-14 and as long as car is started every 1-2 days, alt brings battery charge back up and immediately after turning off the car my voltage reads 12.7v

ive read that some drains are caused by faulty overhead light module. my rear light dome does not work at all, so I thought this may be a good place to start ..pulled the dome down & found the ribbon was ripped in half and not connected to the module. could this be causing the drain?

i also looked into BCM modules but found several different part #s and some look slightly different from each other. will any w211 03-06 BCM module work?

also, is the only SAM in the trunk near the battery or are there others that can cause a drain?

Plutoe

You can find an indy with SDscan and locate the drain in minutes or you can continue to speculate and or go fuse by fuse till you locate the drain. Then replace the faulty component.

Dublinoh

I was thinking the same thing.......you could chase your tail for days. If Star can find this, that is the way to go.

santino

if STAR can pinpoint this down for me that would be ideal ...i'll speak with my indy