e-30 electrical gremlins

[esty]

1987 e-30 - after we bought the car 4 years ago we discovered it had an undisclosed electrical issue, a parasitic battery drain...the battery will drain in a day....Steve chased all of the usual trouble shooting tricks, removed every fuse and relay one at a time but even with the fuses out of the car and the relays pulled, it still has a drain....he also unplugged the alternator and no joy...we ended up putting a battery quick disconnect so we can disconnect when parking the car 

 

i recall reading some place on the web, which i cannot find again that if the battery in the instrument cluster is bad that could be the problem...we know the battery in the cluster needs replaced but have never been concerned enough to pull the cluster and pay big bucks to have the batteries changed...without knowing, i'm a bit skeptical of that suggestion anyway

 

anyone have any ideas or suggestions?

Edited June 28, 2021 by esty

[irdave]

The e30 m3 guys were talking about it on s14.net, but just replacing the battery, not that it had a drain on the main battery...

 

There must be some unfused wires in that thing.

[esty]

seems to me that if there is an unfused wire it would have to come from the battery, there are no extra wires off the battery...anything else would get power directly or indirectly from the fuse box...where else could power come from?

 

[coloincaalpine RIP 2021]

Hook up an ammeter at the battery and see what kind of a drain that you have and then you can hunt it down. Really the easiest way to do this and I have  used this troubleshooting method many,many times.

dq

[20O2Shaman]

Ah, the dreaded parasitic battery drain.  Very common.  Lots of YouTube videos and information on this.  Example -

e30 parasitic battery drain bmw 325e - YouTube  (and many more).

Not vouching for this fellow, or the content - just saying, it's a very common issue with E30s.  No need to worry.

My beloved '84 had a different problem - cold solder joint on the instrument cluster.  That'll kill the car - dead stop, no warning.  Simple fix, but you have to pull the cluster.  Not such a terrible job - rather easy - so if you wind up pulling the cluster, make sure you take care of the well-known cold solder joint problem.  If you need further details, I can help - but I have to search back through my memory - getting old.

So, there you go - my $0.02 cents worth.  I won't even charge you for calling me an asshole on the main board.  If only you knew ...

 

Follow the plan.  All the best, 02Shaman 

 

[Son of Marty]

Esty, if you search on the e28 board you'll find a thread on replacing the cluster battery with a couple of aa batterys, I did this on me e28 and it worked well, I left the wires on the battery holder long enough to hang down below the dash to make battery change easy, the under dash trim panel would cover this when installed, the batterys lasted for about 2 years.