E39 M5 that is convinced its stuck in reverse!

[humpbackmaniac]

My beloved has developed a rather odd condition, she thinks she is in reverse ALL the time. Now I know it happened when an indy changed the clutch, so must be gearbox, trapped wire, or plug related one would imagine. But I have now completely disconnected the switch wires from the box and its still convinced.

Do they run on a positive loop, IE should I plug them in to each other and hope to stop it?

Ive had to remove the reversing light bulbs as a quick fix to stop alarming people behind me and keep her moving but mighty frustrating, must be a duff switch surely? I am sur ehe said he replaced it though.

[simonpa]

On older cars in general, there is a live feed through the lights that gets earthed at the gearbox switch when you select reverse.
Not sure this is what happens in the E39.

If it is, then the cable is probably earthing itself somewhere.

[simonpa]

Looking at the parts:
http://www.realoem.com/bmw/enUS/showparts?id=DE93-...

There is what looks like a plunger switch.
It's possible the switch is stuck in, but more likely the wire is earthing somewhere else.

This page has a schematic, so it's not clear that it's earthing through the switch, but hopefully gives you somewhere to start.

The switch looks to be located on the top of the box, so there is a good chance the wiring comes in from the cabin and under the centre console, making it a bit easier to troubleshoot.

It may be possible to reach the plug from underneath - if you can disconnect it and the light still come on, then you can discount the switch being the problem.

[humpbackmaniac]

Thank you guys, I am sure the wire must be earthing, perhaps he crushed a bit of the loom when repositioning the box back up and its trapped causing an earth short.

Thanks again.

[Schermerhorn]

Yourreverse light switch needs replacing or has a bad connection.