Battery drain problem.
 

'87 300SDL. Constant battery draw. When problem first developed I traced it to the left front seat adjustment circuit. I adjusted the seat and pulled the relay and all was well.

THe problem is back. Pulling the #15 fuse stops the drain.

I checked the seat adjustment switch and there is still a drain with plugs on the switch pulled.

The memory function hasn't worked since I have owned the car.

Question is where is the memory module (relay?) and is it powered all the time.

Thanks,

Tony

The seat controller is under the seat. Yes it is powered at all times so that the seat may be adjusted with the key off.

Thank you Eric, I figured you would have the answer for me.

I'm searching for a new controller. I don't believe an OE part is available, so pre-owned may be the only option.When I find one I'll install it and let you know the result. It may take a week or so to get back to you. It will be nice not to have to disconnect the battery when the car will be parked for for a day or more. Same for doing without the accessories controlled by the #15 fuse.


Tony

Is this a car you're driving daily? If it isn't, you may raise the seat all the way and try disconnecting the chassis-side plug from the seat module underneath the seat and leave Fuse 15 installed. If the power drain goes away, you know you found the problem.

Hi Eric,

THe MB isn't my primary transportation, however I drive it for trips longer than twenty or so miles and trips out of the area to visit friends in southern Oregon. The beer store is less than a mile away. Grocery getting is an eleven mile turnaround.

RIght after I posted a response, and knew the location of the module I disconnected it. The drain disappeared.

The module is available OE, remanned and used. OE from the Fatherland $1500, re-manufactured, exchange from ProgRama $195, and finally, eBay (where else?),prices ranging from $60 to $159.

I found a module at BMW All Parts for $60 plus shipping. If the used one doesn't work, I'll send it in for repair. Not cheap but not the end of the world.

I hope this information along with your contribution helps another owner experiencing the same problem.

Tony