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Discussion Starter · #1 ·
The rear view mirror glass in my XC90 is pretty scratched up, and I know that I need to just replace the glass due to the UEM being all built into that assembly. I assume the auto dimming feature is a requirement when I get a replacement (being that mine is auto dimming), but do I need to get glass from a mirror that has the compass, or is that a separate part? I'd like to keep the compass on my mirror.

I'm sure this has been answered, but I couldn't figure out how to word it.
 

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Rear view mirror is UEM, so if you want to replace the mirror glass, you'll need to separate the electronics (PCB), procedure here- https://www.youtube.com/watch?v=oJb0ELMFeUA, https://www.youtube.com/watch?v=J-Xh9K_a9mA

I looked around, not seeing just the glass unfortunately so you'll need a good donor to do the swap, can use PN 8676965 as a start (looks like just the 07-14 XC90 for this part)- https://parts.volvocarslisle.com/p/Volvo__/67797556/8676965.html

My mirror is scratched as well, interested in replacing if someone ever comes across just the glass as new.
 

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How did you scratch the rear view mirror?
 

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Autodim has a somewhat soft material on the glass surface, mine was already scratched when I bought the '08 in 2015. Manual mirror on the '05 has no scratches despite 13+ years of cleaning.

See link https://photos.app.goo.gl/cJME2TZ31iJu4ztk7 for some visuals, been like this since the day I picked the vehicle up.
 

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Discussion Starter · #5 ·
It's scratched pretty badly, it looks like someone had scrubbed it with a scotch brite pad or a rag filled with dirt. I can still see out of it just fine, it's just not as clear as it should be! I'll try to remember to post a pic tomorrow.
Who knows though, I've only had this car since March. It had probably 3 previous owners, so anything could have happened over that time.

Finding the mirror glass is no problem, I actually just got the auto dimming glass for my S60 (that car's mirror bled out) yesterday at the junkyard, which is what prompted me to ask this question. That was easy... I just removed the glass from the mirror assembly, removed the PCB from the back of the glass (it just clips into place) and I cut the two wires. My S60 does not have the compass.

My question is, do I need to use glass from a mirror with the compass, or is the compass projected from behind the mirror, or a part that I can transfer to the repalcement?
 

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You'll be the first to confirm I suspect but it's intuitive to me to assume that you need an autodim glass that has the compass cutout if your original mirror has a compass.
 

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Discussion Starter · #7 ·
I'm just remembering there's a plastic backing on the mirror glass I got for the S60, I assume the XC90 has the same setup. Obviously the compass isn't going to go through plastic!

I think I'll need one that's got the compass.
 

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Discussion Starter · #8 ·
The second pic shows it best. Like I said, you can still see out of it just fine, it just looks like garbage.


 

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I don't think that's scratches. that looks like the foil separated. can you find a used mirror on ebay? Just swap the whole unit.
 

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Discussion Starter · #10 ·
It does look more like separation when you take a good look at it. I'd replace the whole unit, but as far as I know the UEM needs to be programmed to the car.
 

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I had a closer ok at mine, looks like the staining (although a lot less) is also interlayer. Good catch Tommm. From an earlier question, I'm thinking the compass is a built in LED array in the upper left corner of the mirror assembly and not a cutout but I'm happy to be wrong.

The UEM (remotes) IS the mirror unfortunately so it either gets re-programmed by a software re-load (dealer) or all the guts come off and you swap just the glass.

I'm going to do some looking around, this has to be somebody's "common" mirror glass. I'll update if I find anything while someone does the swap so we can see how it's done (and if there's any identifying information on the back of the mirror itself).
 

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Mine has the 2 vertical lines starting to form, I noticed it a few months back. Sounds like mine may have the same issue as yours eventually.
 

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Exactly what has to be programmed? I changed the mirror in my 128i from one with just the "clown nose" for the alarm to one with homelink and auto dim. I needed to add one wire for power and it's been fine the last 3 years. I bought it from ebay. almost plug and play.
 

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Exactly what has to be programmed? I changed the mirror in my 128i from one with just the "clown nose" for the alarm to one with homelink and auto dim. I needed to add one wire for power and it's been fine the last 3 years. I bought it from ebay. almost plug and play.
Slap a Volvo replacement mirror assembly in (used or new, does not matter) and see what happens. Keep the old mirror around to put back when you're done- https://forums.swedespeed.com/showthread.php?526986-UEM-Replacement-Reprogram-HELP!!!

Did my wife's Mazda right after she bought it, same as you did (homelink/autodim). Was as literal plug/play so was even easier, took a whole 45 minutes.

But this ain't a Mazda, it's a Volvo, and in the mirror is the Upper Electronics Module (UEM), an active device which is the interface for managing up to 14 functions including the remotes.

You know I don't make this stuff up, I actually considered a pick/pull a number of years back as a possible option to replace a lost key. See VIDA section 372: Design and Function (UEM) and System overview for a very good description for what this module manages.

*UEM manages the following:
Siren (SCM) (XC90, applies up to and including structure week 201127)
Sun roof
Mass movement sensor module (MMS) (does not apply to the XC90 MY 2012-)
Ultrasonic sensor module (IMS) (only applies to the XC90 MY 2012-)
Rain sensor module (RSM)
Interior roof lighting
Sun visor lighting
Remote control
Automatic rear view mirror anti-dazzle
Seat belt reminder
Tire pressure warning
Indication of disconnected passenger airbag (PAD- Passenger Airbag Deactivated)
Compass
 
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