So I had my 2008 535i down for about two weeks while I was doing cooling system repairs. I was opening the doors often as I stored stuff in there I needed. One occasion I opened the doors, car woke up, and all the dash lights flashed. Car does have a JB4 and up till today I've had the gauge hijacking set for water temp on fuel. So anyways, I got the car running and have had the "High Battery Discharge" warning every time the car sits more than a few hours. I tried a closed circuit draw test with a generic probe ammeter but realized it only reads 200A. So I decided to use the mV feature to put the car to sleep and just test every single fuse. So I did. And I found only two fuses having any kind of voltage drop. One was a 10A, not sure what number fuse, but it had 0.2mV at sleep. Stands alone in the glovebox fuse box. Further down that row of fuses if F41, last fuse on the 535i in the glove box. I found 1.6mV running across it. I figured this was my draw and I pulled it and left the car overnight. I came back to go to work this morning and reinstalled the fuse and low and behold, no discharge warning. I did start the car with the fuse pulled just to see if I could tell what it was. Its the instrument cluster apparently. All that being said, I have a few questions. First, is it possible that having the fuel gauge hijacked for water temp by JB4 is causing it to stay on, as the temp stays displayed on the fuel gauge after I turn the engine and ignition off? I am at work and left the fuse installed and turned off the water temp feature on the JB4. Will report back on that. Second question, if that JB4 is not the problem, I'd have to assume instrument cluster is the issue. So my question is if I was to buy a used one off eBay, is there anyone on here or a website you would recommend that could program the used cluster to my car, vin, mileage, etc? I am not looking to get bent over by my dealership. Also anyone local who could help in FL would help a lot.

 

well Incase anyone has a similar situation, my case the draw was indeed at the cluster but it seems to me, leaving the jb4 in any other map than 0 keeps the cluster awake. In map 0, F41 sees 0.0mV.

 

I've been researching vendors to fix my instrument cluster. Mail it to them, they mail it back. I'm finding out the average price is circa $150.

However, a used cluster on eBay with my approximate mileage can be as low
as $50 (the fact there is a small red dot on the cluster because it has not been coded yet, won't kill ya).

 

turns out it’s the jb4. Drains in everything but map 0. Keeps the cluster awake

 

Is it supposed to do that. I've never heard anyone with that issue

 

well no it most definitely is not supposed to. I had the sitting for two weeks while I was fixing cooling system. Opened the door one day and it flashed all the dash lights at me. I’m assuming that’s when it happened. As far as what’s actually causing it to stay awake, I’m clueless as in map 0 w jb4 still plugged in, car sleeps fine with no drain warning.

 

Did you install it yourself or someone else. You may want to have it looked at