[BMWfan73]

Just picked up my new to me 2015 X3 and so forgive me if this seems like a silly question but I'm just trying to learn all of the nuances of the vehicle. The rear view mirror is always dark. Doesn't matter if it's sunny outside or night time. Is it supposed to be like that? It doesn't seem right to me.

[pungo]

I assume you're talking about the inside mirror? Are the outside mirrors dark too? Do you have the auto-dip mirror option? If so, maybe it's stuck in dip mode or it's just failed. If not auto-dip did you try turning the knob on the bottom of the mirror as specified in the owners manual?

[willywi]

Originally Posted by BMWfan73

Just picked up my new to me 2015 X3 and so forgive me if this seems like a silly question but I'm just trying to learn all of the nuances of the vehicle. The rear view mirror is always dark. Doesn't matter if it's sunny outside or night time. Is it supposed to be like that? It doesn't seem right to me.

Did you have anything mounted infront of light sensor? I had this issue when my dash cam blocked the sensor so the car will think it's dark outside and dim the mirror.

[frisbeeguy]

Not Normal.

[BMWfan73]

@willywi no, nothing is blocking it.

[BMWfan73]

Originally Posted by pungo

I assume you're talking about the inside mirror? Are the outside mirrors dark too? Do you have the auto-dip mirror option? If so, maybe it's stuck in dip mode or it's just failed. If not auto-dip did you try turning the knob on the bottom of the mirror as specified in the owners manual?

@pungo they're auto-dip. The side view mirrors adjust properly. Only the rear view is "stuck" in darkness.

[pungo]

Originally Posted by BMWfan73

@pungo they're auto-dip. The side view mirrors adjust properly. Only the rear view is "stuck" in darkness.

Silly question, but the rear windshield is probably privacy glass, right? Is there addition window tint film on the rear glass? Either may make the mirror appear darker?

You can test the dip mode at night with a small flashlight by shining it into the sensor on the glass of the interior rear view mirror to watch for changes in darkness in the mirrors. I believe the sensor in the front windshield can tell it's daytime so the so the flashlight trick won't work during the day, well, maybe if you cover the light sensor in the front windshield?

[frisbeeguy]

Well, I think I figured out your issue.

There are 2 sensors, one in the rear to detect day/night and one in the front to detect light. My guess is your rear sensor is either covered or not functioning, thus causing the front mirror to always be dark since there's always light shining on it. Also window tint in the rear/rear privacy glass will not affect functionality.
Check out this video to test it:

[pungo]

Originally Posted by frisbeeguy

Well, I think I figured out your issue.

There are 2 sensors, one in the rear to detect day/night and one in the front to detect light. My guess is your rear sensor is either covered or not functioning, thus causing the front mirror to always be dark since there's always light shining on it. Also window tint in the rear/rear privacy glass will not affect functionality.

The OP said his side mirror are dimming, so that should mean all the sensors are working correctly.

When I mentioned window tint, I was referring to looking in the mirror out though the back window which will appear darker because you're looking through a privacy tinted window, as compared to the side mirrors which you're not looking through privacy tint.

Window tint will effect the sensitivity of the sensor. The darker the tint, there less sensitive the sensor. There's even a coding setting to adjust the sensitivity for different levels of rear window tint. Rear windshield limo tint will make the auto-dip darken much less often then factory tint.

[frisbeeguy]

Originally Posted by pungo

The darker the tint, there less sensitive the sensor. There's even a coding setting to adjust the sensitivity for different levels of rear window tint. Rear windshield limo tint will make the auto-dip darken much less often then factory tint.

Gotcha. Interesting info.

[6MT_Addict]

Your interior mirror is probably toast.

Hold a black piece of paper over the front sensor (facing the windshield) and shine a flashlight on the rear sensor (the one on the mirror glass), see if it responds, or if the side mirrors respond.


If your side mirrors darken, but interior mirror does not, replace the interior mirror. Get a new (used) one from eBay, it'll run you a hundred or so bucks.

[BMWfan73]

Solved the mystery. I finally had time to inspect the trunk glass and the rear doors (which are equally dark) and it looks like the PO had them tinted. Pretty dark. Whoever did the tinting did a great job, though. It took a while to even detect the film. Finally found a spot on the rear glass where the trim line went slightly uneven with the curvature of the plastic trim. Otherwise, it was really hard to tell that it had been tinted aftermarket. I guess I'll either have to just live with it or remove it and have everything re-tinted a little lighter. Good thing for the backup cam and PDC,