No crank situation - new type of failure?

[Steve119]

Hi all,

Wanted to share a new type of no-crank failure, at least for me.
I'm working on a higher mileage 500E and suddenly it had a very intermittent crank, and shortly after absolutely no crank.

The classic diagnostics revealed the starter is OK when manually feeding it.
Ignition switch also wasn't the cause.
I then check the wiring (purple/white and purple) from the NSS towards the starter, and no juice.
When jumping the 2 wires in the NSS connector I had a starting engine!



So a bad NSS was the conclusion...but then I took it out and found the real culprit:



A broken plastic lever!
Checked the NSS with the multimeter and it's fine, so instead of spending 160€ on a new one, I went on to search for a used 6cyl/8cyl NSS to swap out the lever.
Nothing on the yards nearby, so I just bought a new 12€ Topran switch, took out the lever, and voila... fixed NSS and back to a cranking 500E!

switched levers:



It must be some kind of plastic fatigue, or it took a beating once... but I though good to know that it can happen and be a no-crank cause.

 

[gsxr]

Good detective work, Steve! And that was a good repair as well. You can't use a 6-cyl NSS because it lacks the gear position signal that the V8's require. Borrowing the lever only was genuis.