Totally off topic! E39 BMW Battery Drain issues!

[MertzMan]

This is about as far removed from Bushcraft as possible but my E39 has a parasitic draw. Maybe someone here is an auto electrician or has suffered the same fate?

I've traced this to fuse #4 and #9. Heated washer system/interior lights and AC system respectively.

FSU's are known to go bad on these and have had several re designs but I can still moderate the fan speed on the AC control from the drivers seat just fine. So it's either intermittent or something else on the two circuits. AC needs a re gas but that's another issue.

Any ideas? I'm about ready to burn the car to the ground.

 

[mjojom]

why dont you pull fsu out and see if thats sort out the issue? also interior lights are on the same circuit, so how about glove box light -quite common too? you can also disconnect cables for heating wash system (under the bonnet,) you hhave not said if its saloon or tourer. if tourer, hows the tailgate wiring under the roof>?

 

[Coldfeet]

Remove one of the fuses, and see if the problem continues - that should identify which one (if either or both) are to blame. Once you have sorted, trace the loom and see if you can find any damage; you could find that a cable's rubber protection has worn away, and a cable on the inside is grounding on the bodywork.

Other than this, I can only really say take it to a professional. All depends on how much time and money you have to ]fix it.

 

[feralpig]

So what you are saying is, that when you pull either of those two fuses, the parasitic draw drops off?

How does the heated washer system work? Is there some kind of regulator that is not shutting off properly?

The very first thing I would be checking is that there is not an interior light in the boot, that is staying on when the lid is closed.

Quite why there are two fuses involved, I don't know. I guess it is possible that there are two problems, on the different circuits.

Failing to find the boot light, I would be inclined just to disconnect everything on those circuits, and reconnect, one by one.

You have my sympathies. Finding parasitic draw can be challenging. At least you have it down to the two fuses.

Edit. This is probably not the issue, given you have isolated it to two fuses, but do you have a face-off radio? These can be real stinkers for drawing, when switched off. For reasons i don't quite understand, the face will switch off, and leave the internals on. Normal, not face off radios can do the same, but I've seen more trouble with face off ones, it's the next immediate suspect, after the boot light, for me.
It's probably not it, because it's probably not on those circuits, but it's worth knowing about.

 

[crosslandkelly]

Check that your boot light doesn't stay on, a faulty switch is often to blame.

 

[cbr6fs]

Is there a aftermarket alarm fitted?

 

[Goatboy]

Some good ideas so far. Have you looked at the earthing strap on the car? Can often cause similar problems which a clean up and making sure it has good contact at either end will often cure.

Sent via smoke-signal from a woodland in Scotland.

 

[brambles]

Not to worry you, but I had a client with a similar problem and it turned out be a consequence of the surveillance devices planted on the car by the police .....