farhanali89

Hi all,

im tackling an issue for a potential battery drain, i have aftermarket audio equipment and i have reverted everything back to standard to narrow down the issue.

i am running a test on fuse 67 in the rear Sam (Harmon Kardon amp fuse) with the car locked I can see this fuse is still powered and not going off. Can anyone confirm if this fuse is a constant live?

fuse 67 (30amp)

I am aware everything on the command chain e.g. DAB, media interface, HK could all be the culprits but knowing whether this should power down will help identify whether i need to look further up the chain.

deadlyvt

Mine has a drain somewhere as well and my command screen will actually open up and then shut with the car shut off and the doors locked. I didn’t spend much time searching for the issue as I’m either replacing the pop up screen and then I’ll search fort he drain or deleting the sound system altogether
But I’m interested if you can find it, I’m guessing whatever is your issue will be mine

farhanali89

hmm, will keep this thread updated with findings but some slight differences to note

my car is a 2013 with the fixed command so slight difference on the NTG version. Just concluded a short test. I tested the Harmon Kardon fuse after 1 hour 40 minutes with the car locked and it did power down my test light.

It may just be the characteristic of that circuitry and not a drain. I checked voltage on the battery and it was still 12.06.

The Machinist

Do W204’s have relay or fuse compartments that are exposed to the elements, or would become waterlogged if a roof drain or taillight seal were to degrade?

If so, I would look for a relay that has corroded contacts.

I was chasing a battery drain on my A8 for over a year, when I discovered a relay compartment on the passenger side floor board that was getting water running down the wiring harness where it penetrates the firewall because of a plugged rain tray drain.

The relay that controls the interior button and gauge backlights was corroded internally and the contacts were stuck together. Intermittently.

Externally, the only clue was corroded contacts which were not visible until the relay had been unplugged.

roadtalontsi

Are you doing an amperage draw test? checking voltage isn't really going to help you unless it's a massive draw. I'll check the wiring diagrams and let you know if 67 is a constant power when i get a chance.