2006 X5 3.0i keeps running with key off
 

I would pull your FSU and see if things stop acting odd.

How did you get car to turn off when it didn't initially?

Or just fuse F64 which is continuous voltage supply for final stage. Though that couldn't explain voltage circuit to terminal 15 rail because it would go via IHKA on a 0,35 mm2 wire. It can cause voltage drain which could explain alarm going off when battery voltage drops.

https://www.newtis.info/tisv2/a/en/e...-stage/nuYFLtI

https://www.newtis.info/tisv2/a/en/e...4i-sav/UzR4ORT

I think I put the key back in, turned it forward, and then turned it back off. Either that or it turned itself off after 15-20 seconds? It's happened a couple of times and I don't remember exactly what I did but I'll see if I can replicate it.

It's such a random problem. It's done this mess now and I could probably drive it for the next 2 months without an issue. Then it would pop up again.

Sorry, I'll ask the stupid question. FSU? I haven't been on this forum in a while and haven't kept up with the things I probably should have. FSU is too short to search so I'm stuck asking the question :)

FSU = final stage unit = final stage = output stage = hedgehog

It's inaccurately referred to as the FSR final stage resistor as a carry over from the 1950s where blower speed controlled by a series resistor that was in the blower air stream to cool the insane power loss on the m resistor.

On the e53, it's easy to get to: it's almost dead center in the car access from the right side of the console carpet panel.

Or like said just remove fuse F64 which is easier and has the same effect.

I was pointing out for the case if it needs to be replaced. Fuse good for testing but I wasn't sure all the wires going into it so did me it would literally be just as fast to pull the hedge vs find the fuse to pull.

Thank you! I'm going to spend some time tracing wires this weekend.

Well, I had an experience. Right now, it's not my daily driver but I had to drive it to an outside event where I'd be close to it the whole time. Started and drove fine to the event, then when I got there, I turned the key off and it kept running. I took the key out and it kept running. Everything works, the radio, locks, windows, all work like nothing is wrong. It will not go into drive, that's locked out from moving.

I left it running and got out, shut the door and just watched it. It ran for a couple minutes, I guess, then it cut off and all the lights were on. I walked over, the AC was running. I put the key in and started it and got the Trans Failsafe Program message and the BRAKE light was on. I couldn't do anything to make it stop. I opened the rear hatch and got some things out I was using, and it all eventually cut off, lights and all. Then I walked back to the car, at the open hatch and noticed the A/C was running again.

I was there for about an hour and the whole time it was cycling on and off at it's own will. It would never start on it's own but it certainly would be fine, all lights out, no issues and then I'd look over and the lights would be on.

Never once did the alarm go off, but I suspect the reason the alarm goes off at night time is because this happens and it sits there and drains the battery until it hits that critical point, at which time it sets the alarm off. That's just my guess, I could be wrong. That, to me, sort of means the alarm part is kind of a red herring. It's not triggering the alarm and the issue happens, it's the issue happens, which triggers the alarm from the voltage drop. Maybe I'm wrong, I don't know.

When I left the place, the Trans Failsafe message was up, the BRAKE light on, and I drove slowly leaving the place, stopped a couple times to turn it off and restart it in hopes it would reset itself, but nothing stopped it. I drove it 20 miles back with those lights on, it ran perfectly. When I got to my destination, I turned it off and it just turned off like everything was fine.

That's the first time I've ever been around it when it's going through it's craziness from start to finish. That's the behavior it's had very rarely in the past, but now, since changing the ignition switch the other day, this seems to be front and center now.

Hopefully I've recounted it accurately and maybe something I said will be obvious to someone that may offer some advice.

I was without internet or cell connection, otherwise I would have tried pulling the fuses mentioned earlier, but I had no way to pull up this thread to see the fuse numbers. I'll be poking around it this weekend once I hear some advice about today's experience.