E36 Mystery Parasitic Drain

[SitzeMann]

Hi Guys,

I'm in need of some help. I have an assumed power drain on a car that I cannot track down.

I say assumed because the car had a problem draining the battery when sitting for a week +. The battery tested ok multiple times but ultimately went bad and has been replaced. The question now seems to be if the battery was always bad or the parasitic drain killed the battery.

I have a meter on the car and I read about a 120 mA drain when the car is asleep. That seems like too much but I cannot find any information which says what is normal.

I have pulled every fuse I can find, under the hood and under the column without any impact to the current draw. I have unhooked the black cable from the fuse box because I read about some which saw a change when that is removed, again no change. I had the alternator unhooked completely to ensure it was not a bad diode, again nothing.

I have suspected the parasitic drain was connected to the EWS system going bad, which happened roughly the same time as the drain was noticed. The EWS read was flashed out of the DME but I have not removed any of the hardware. However, I have disconnected fuses on the EWS circuit without effect. Generally that would debunk my theory.

Any help, experience, advice is appreciated!

[MarcoZandrini]

Yes, 120ma is way too much. Typically, 40-50ma is what you should see. You’ve done your homework and done all the usual suspects. Does the drain remain constant or does it vary?

[SitzeMann]

Constant as can be.

I’m stumped.

[MarcoZandrini]

Has the car ever suffered water damage? Have you disconnected the starter as it’s connected directly to the battery?