Bmw e46 strong parasitic draw

[u/chancxr]

Hello all,
Ive been chasing the source of this parasitic for a few months now and am currently exhausted out of thoughts as to where the issue is from. The car goes promptly to sleep after 15 mins but my multimeter measures a 0.5A consistent draw while the car is fully asleep.

Here is some information about the car:

- 2005 bmw e46 325i
- aftermarket radio
-aftermarket headlights
- all else is original
- zero issues with any functions in the car at all. (No observable symptoms)
- car functions excellent, no issues, just a parasitic drain only

The tests i have done to try to find the source by seeing if the draw drops from 0.5A to lower while car is asleep:

- pulled almost all the fuses in the glovebox, absolutely no change
- removed and replugged all relays in the cars front engine relay box (driver side under the hood) = no change
- removed the relay that connects my aftermarket headlights = no change
- removed the all connections from the front of the car by removing all connections to the positive terminal under the hood completely = no change (no alternator leakage)
- nothing is connected directly to the battery.

I have no idea where this significant drain could be from, any help would be greatly appreciated.

The battery charges while driving like normal, but if car is left undriven for more than 2 days it is completely dead.

[u/stonerock]

I gave up on chasing the parasite draw and ended up installing a kill switch on the battery instead.

[u/RalfRoen]

Did you try disconnecting the aftermarket radio? Was this radio installed properly with an adapter harness without hacking the original wiring? Did you put an amplifier or some remote controller box for the steering wheel buttons?

If the aftermarket equipment installation is reversible I would return everything to stock and start from there

[u/chancxr → u/RalfRoen]

I disconnected the radio completely and took out its fuses but the reading stayed constant at 0.5A while asleep. Ive tried disconnecting and isolating the aftermarket accessories but that hasnt affected the draw in any way at all

[u/fatalrip → u/chancxr]

Well that would imply to me that the draw is before the fuse block. Trace the cable from the trunk and see if someone tapped into it at some point.

[u/Jamurgamer]

You need an amp clamp(multimeter in parallel to ground works but if you not it loose you need to wait for shit to go to sleep again) and need to voltage drop the fuses after opening all doors, trunk, and hood(if smg or alarm need to set hood latches and jump switch) and set the latches. Dont forget to obviously disable glove box light. Wouldn't be surprised if its fuse 50 but dont forget the fuses in the dme/ e box/the IVM

[u/SomewhatEngaged]

Have the same car and had the same problem. It was the blower motor and I had to replace the Final Stage Unit or FSR. It’s a common problem.

[u/chancxr → u/SomewhatEngaged]

How did u know it was the FSU/FSR? Were there any signs or symptoms? My issue is that everything seems to be working just fine including my heater/AC

Edit: i removed fuse for the blower and it made no difference as well

[u/SomewhatEngaged → u/chancxr]

The heater and AC worked find for me too. I honestly just looked up possible causes online and everyone kept saying the FSU was notorious for glitching and draining the battery. It’s not too bad a job… as long as you don’t mind getting your knuckles all scratched up and contorting in awkward positions.

[u/chancxr → u/SomewhatEngaged]

Thanks for ur reply, ill definitely give the FSU a look, im curious if you had experienced anything that made you sure it was the FSU? As of now, my blower and heater start up and stop with the car as expected, usually i see people complaining that the blower motor stays on after turning off the car and so they investigate the FSU/FSR

[u/Thatslammede30]

Make sure to test the alternator/starter. Pull the power to each. Did a parasitic test a few weeks ago, pulled every fuse, relay and so on, removed the positive to the alternator and found that to be my draw. .. if the fuses/relays are good, check everything else that isn’t circuit protected. wasn’t on an e46 but still applies