OP hasn't posted the results yet, so we don't know what exactly it was.
But I had a similar experience with my old Mercedes. It was a brake switch. At that time, brake light didn't come on, all the error messages came on, shift lever didn't come out of P position. After a couple of hard braking, switch came back to life and I was able to start and move. Later there was a brake switch recall(related to disengaging cruise control) and replaced the brake switch and haven't got that problem since then.

I wanted to resurrect this thread since it had all of the same issues I was having.



Carly was having a fit with it as well, and I had no real direction to go in. I had already replaced the glow plug controller and all of the glow plugs two years ago.



I pulled and bench tested the starter, checked the relay in the rear fuse panel and checked the brake switch. Everything was fine.


Ended up checking the engine ground as a last resort. Its on the driver's side of the block, down by the motor mount in the lower part of the wheel well on my 2012 E70 diesel. It was completely corroded and fell apart in two pieces while I was trying to remove it. It sucks that it cost me $50 at the dealer for a new ground strap, but now its starting again and no more "pre heating" message. Before, nothing would happen. Since my truck has the Xenon lights, I could hear a zapping/arcing sound when trying to start it as well after the truck refused to start. I'm guessing it needed the engine ground as well since the arcing noise has gone away after I replaced the strap.



I don't know why the engineers felt burying this strap made sense. It can get wet and there really isn't any air circulation around it to help it dry out.

I hear a zapping or arcing sound only when preheating. Or a slight one if I turn on the headlights with the engine off but HID bulbs quite literally strike an arc to produce light.

Try running a jumper cable from the jump start ground lug under hood to the lift point behind the front egr cooler

I definitely did this :thumbup: That is what I had done to finally diagnose the issue. Worked great. Kind of wished I had done it in the first place. I just never expected the issue to be a ground strap.

There’s a lesson in this...

BMW engineers sit and develop flowcharts and diagnostic routines for all sorts of codes.,,,BUT... these are only as good as their imagination, forethought and experience.

Sadly, when we sit with cars for 10+ years, *we* discover failure modes they never considered.

A rotted ground strap...water leaking in clogged sunroof drains... the list goes on.

Its part of the reason a ‘crowd sourced’ diagnostic community like BF can be, in fact, better than any single dealer or dealership mechanic. They are good, very good, but they may not ‘see’ as many as a forum does.

:thumbup:

Agreed.
It's also identifies a delineation between engineers who actually turn wrenches and those who play with spreadsheets and CAD when making the original designs.

I love working on my fj40 and loathe working on my X5.