Rear view mirror - auto dimming

Z-4-FUN · Post by **Z-4-FUN** » Sat Jan 11, 2020 7:05 pm

I'm after a replacement auto dimming rear view mirror for my E86.

Mine has stopped working. I assume it's a issue with the internal sensing mechanism as the wing mirrors aren't dimming either.

Z-4-FUN · Post by **Z-4-FUN** » Mon Jan 13, 2020 5:52 pm

Can anyone confirm the part number I need? There seems to be different variants available on fleabay and I want to make sure I get the right thing.

Essentially the rear view mirror isn't dimming, and neither are the wing mirrors. Therefore I think the light sensing components needs to be replaced. I also have arutowipers, and believe the sensor for these is also built into the mirror housing - these are working fine.

I'm happy to buy a complete mirror assembly but if it's a discrete component I need, perhaps that's the most economical solution?

Sidewaze Samm · Post by **Sidewaze Samm** » Mon Jan 13, 2020 6:04 pm

Z-4-FUN wrote: ↑Sat Jan 11, 2020 7:05 pm I'm after a replacement auto dimming rear view mirror for my E86.

Mine has stopped working. I assume it's a issue with the internal sensing mechanism as the wing mirrors aren't dimming either.

I don't know for certain, so may well be wrong with this, but my understanding is the dimming sensor etc is all contained in the mirror housing itself. Have you definately got dimming door mirrors? AFAIK having a dimming interior mirror doesn't necessarily mean the door mirrors are dimming too.
Use RealOEM to identify the mirror for your car and then use the part number on ebay. Good luck.

EDIT - post the issue in the problem section, and hopefully someone with more knowledge than me will help...

Z-4-FUN · Post by **Z-4-FUN** » Sat Feb 08, 2020 9:05 pm

It turns out the auto-dimming feature is a known weakness with the electro-chromatic glass in these mirrors.

Unfortunately there was an issue with the manufacture of these original mirrors which causes them to fail. They will all fail sooner or later. It is more 'When' the mirror will fail rather than 'If' the mirror will fail. Due to the poor original design, when the mirror fails it can cause devastating permanent damage. There is a (dimming) fluid sandwiched between two pieces of glass and this liquid is highly corrosive. When the mirror fails it can allow this liquid to leak out. When it leaks out the glass it will eat its way through your mirror casing and then damage anything it drips on to: centre consoles, gear knobs, seats, dashboards, etc.

As it seems like an inevitable failure, rather than sourcing a secondhand mirror on eBay, I purchased a replacement glass (of updated design) from MirrorJohn, who seems to be a well regarded member of the M3Cutters forum.

If you run into the same issues, I suggest you google him. His solution isn't cheap, but it's 1/4 of the price of an OEM unit, and seemed like a smarter idea to get an upgraded part rather than throw similar money at a second hand part which could fail at any point.

NOTE: MirrorJohn only provides this service for the oval type mirrors, which are common to E46 M3's

kis · Post by **kis** » Wed Feb 12, 2020 5:52 pm

I assume you swapped to a M3 mirror then? And that’s working fine with your side/wing mirrors? Plug and play?

Z-4-FUN · Post by **Z-4-FUN** » Tue Feb 18, 2020 6:12 pm

I didn't personally swap it as it's what came in the car when I bought it. When I was looking for a fix I noticed from trawling through loads of photos that there were 2 different shape variants of mirrors installed in the E85 and E86's. I have no idea if the M3 mirror in my car (or others which I've seen) was there from the factory or if it, and others, have been replaced over the years.

I am aware that a lot of the E46 parts are compatible with E85 and E86's. My rear view mirror now dims perfectly as expected. It has exactly the same electrical connector and mounting bracket, so unless you'd just seen another car with a trapezoid shape mirror, you wouldn't have any reason to question if it was the original part or not.

I cannot comment on the wing mirror dimming as someone has replaced the glass units on mine with standard glass - I assume they failed and were too expensive to replace with dimming components (which are cost around £500 a piece!). But as the electrical connector is the same and it's not thrown up any error codes, I'd assume it's completely compatible.

kis wrote: ↑Wed Feb 12, 2020 5:52 pm I assume you swapped to a M3 mirror then? And that’s working fine with your side/wing mirrors? Plug and play?

kis · Post by **kis** » Tue Feb 18, 2020 7:57 pm

Thanks for the update, will do some digging on real oem. Let’s see what happens!

Z-4-FUN · Post by **Z-4-FUN** » Wed Feb 26, 2020 12:26 am

For those of you who are interested, the mirror fitted to my car is part no. 51167892264

As detailed on RealOEM, this was a common part fitted to Z4 E86 (10/2005 - 08/2008) and 3 Series E46 (07/1999 - 08/2006).

I think the important specs which ensure compatibility are that they share the same electrical connector and the radio frequency of the central locking radio module is 433 MHZ.

Z-4-FUN · Post by **Z-4-FUN** » Wed Feb 26, 2020 12:33 am

I am also reliably informed that the E86 (and I assume the E85) share the same wing mirror glass as the M3, which helps for those looking for replacements. You can also get these from MirrorJohn (blue tinted). Do however note that because BMW switched sides of the electrical connectors for the heater elements, you will need to get the variant with the heater extension wires. There's an explanation of this here.

Z4-forum.com

Z4-forum.com

NO LONGER WANTED Rear view mirror - auto dimming