Just an update on this for anyone interested....had a look in the fuse box this morning, fuse 57 has blown (5 amp). Hopefully this has protected the sensitive control unit (wherever it is..!). Will pop the pass mirror off tonight and see if there is anything going on.

 

I think the control electronics are integrated in the driver's side mirror on the cars with ribbon cable mirrors. I had a fault where neither of my mirrors were working, and I had fault codes for the passenger one. Anyhow after checking them both the ribbon cable on the driver's one was badly corroded, passenger side one looked okay, so I replaced just the driver's mirror, and now both mirrors work fine.

I bought genuine driver's side mirror internals for £180 from a dealer, not cheap but like you I couldn't find any second hand ones, and I wouldn't trust second hand ones to be honest seeing how fragile the ribbon cables are.

You can attempt a fix on the ribbon cables if you are careful/lucky, by soldering in thin wires to bridge any breaks - sanding off the protective lacquer over the copper tracks helps the solder to get a bond. There's also a piece of ribbon cable buried inside the mechanism connected to the circuit board, which is a less obvious place for it to fail.

 

Tim-Ci, thanks very much for your reply...

I popped the fuse board out and replaced fuse 57 (with the pass mirror disconnected) and that has restored the drivers side mirror to working order.
Removed the pass mirror and can confirm a 2" section of one of the wire tracks has corroded out where it comes through the door. Not good. So, i've cut that complete section out and crimped in a section of normal cable. Run out of time to connect it all back up now, so i've slaved the mirror back in without elec connection and will have a gentle play with it tomoz....

 

Crikey you got stuck in. Well that could nail it, if it's still not working you could take the cover off and follow the mirror cable down to the circuit board to make sure there are no breaks there. I remember there was some soft hot melt type glue on top of the circuit board that needed scraping off to get to all of the cable, and there was a break in the track under that glue. I think the mirror cable material could go down as an engineering fail personally, I expect to have to fix it/replace every 5 years or so.

 

Well, I repaired the wiring to the pass mirror and connected it all back up again. Turned ignition on and neither mirror works. Fuse is ok. Disconnected the pass mirror again and the drivers side works ok. So there is obviously still an issue somewhere. Have left the pass disconnected for now and will look at it again when I i'm not so fed up with it..!
Guess it will be a trip to BMW for new mirror internals ��

 

How annoying. Have you checked the driver's side mirror wiring?

The circuit for the passenger mirror control passes through the wiring on the driver's mirror, so if that's broken then it could explain why neither mirror works with the passenger side one plugged in. Mine had passenger mirror errors only and the only thing I did to fix it was to replace the driver's side mirror internals, didn't do anything to the passenger mirror - the ribbon cable was shot in several places on the driver's side, down to the circuit board as well as the bit that gets flexed when the mirror is moved, and my solder fix on that cable didn't work.

It's worth checking the wiring on the other side in my opinion, at least after a bit of practice getting the door cards on and off becomes easier!