tdoh

Is it normal for the auto-dimming rear view mirror to dim even during the day when there is sunlight? I thought for a moment that perhaps the rear window might be slightly tinted or something (light bluish) but for the heck of it I turned off the auto dimmer and next thing you know the rear window looks a lot brighter when looking at the rear view mirror.

Anyways, just wondering if any of you guys notice the same thing on yours.

Tony

wakkolio

Auto dim shouldn't turn on during day time.

pianoman41

The auto dimming mirror has nothing to do with darkness. In fact, it's the opposite--it's activated by the *presence* of light. The little sensor on the opposite side of the green "on" LED is the photocell. Whenever *any* light is present it dims the mirror. The more direct light into the sensor, the more the mirror dims. It is designed like this so when a car is directly behind you shining its headlights at your mirror, you get maximum dimming. As soon as the car goes away the mirror lightens some to help you see behind you at night when there's no direct light source.

Try this on a bright sunny day. Close your sunshade on the moonroof and turn the mirror on. Give it about 15 seconds to adjust to the ambient light (it doesn't change instantaneously). Then slide open your sunshade and watch what happens. Even though it's not direct light it's enough to dim the mirror.

You can also take a flashlight (day or night) and shine it at the sensor and watch the mirror dim. Conversely, at night when a car is behind you and it is full dim, you can put your thumb over the sensor and the mirror will switch to full lightness.

This is why it does function in the daytime and why there is a switch to turn it off. FWIW I leave mine on all the time.

bricot

And make sure you don't have anything hanging from your mirror that can get in the way. I hung a parking permit from my mirror and it was screwing with the dimming.

LarryLynx

You can also see its effect when you are in the shadows (such as your garage with the door open, or in a shadow on the road) and the mirror is reflecting images that are in the bright sunlight behind you.

TLinBama

My mirror dims when I first pull out of my garage. It kinda threw me off, but by the time I put the car into D5, it's back to normal. It's just the photocell in action...

amcl

There are, in fact, two photosensors on the rear view mirror. The most obvious one is NEXT to the green led. However, there is an additional sensor on the BACK of the mirror. You can feel it with your fingers - there is a circular opening. It's these two sensors that work in conjunction to automatically dim your mirrors.

When you're backing out of the garage, the sensor on the Back of your mirror see's dark, and the sensor on the Front gets sunlight so the mirrors DIM.

You can manually dim the mirrors by blocking the Back sensor with your finger during the "Daytime" so that the mirror thinks it's dark outside, but the Front sensor registers bright sunlight just the same as a bright headlight so your mirrors will start to DIM. Try it... it's fun to watch!!!

amcl

Road Rage

For safety, the dimmer capability is de-activated during back ups with the car in reverse.

gohawks63

However, there is an additional sensor on the BACK of the mirror. You can feel it with your fingers - there is a circular opening. It's these two sensors that work in conjunction to automatically dim your mirrors.

Didn't know that. Go figure, I learned something new today. I guess I can go home.

edgalang

Exactly. I demo this to my friends by blocking the back sensor with my fingers and flashing a flashlight on the sensor next to the green led. This creates the MAXIMUM light difference, since the back will have no light at all thinking its pitch black, while the flashlight will simulate a car with highbeams on. Too bad we dont have an auto tinting windows instead.

quazi

I must admit, I do not like the way the Acura handles this.

My Lexus RX dims when it detects light in the from the rear (i.e., a car from behind) rather than detecting dimness in general. The result is no dimming when there are no cars behind you, and dimming when there are. The RX also dims more darkly.

I love my TL-s, minor stuff, but just thought I'd ***** :p

edgalang

I dont quite understand your statement. How is the Lexus one any different or any other autodimming feature on any car for that matter. How could your lexus autodimming rear view mirror work without any form of light sensor? Are you upset at the fact that we can "simulate" cars with highbeams behind us? Perhaps you aren't trully aware on how this feature works. The greater the light difference between the front and rear of the mirror, the greater the dimming effect. I personally think its great, since it's dynamic, and contains no moving parts.

tdoh

I guess then that the auto-dimmer on the TL-S must be light years ahead of the auto-dimmer on my Tahoe, technologically speaking. However, I thought that the main--if not sole--purpose of an auto-dimming rear view mirror was so that you don't get blinded (or is it glare) from looking at other vehicle's headlights when it's dark (usually nighttime). IMHO--I see no practical purpose for the rear view mirror to dim at all when there's enough sunlight outside that people don't have their headlights on (DRLs notwithstanding, but they're not as bright as full-on low beams anyway, or at least shouldn't be). For this very reason I say that the autodimmer on my Tahoe functions more practically than the TL-S one.

BTW--do the side mirrors dim too? I might have missed it but I didn't see anywhere in the owner's manual that states that the side mirrors auto dim also. If they don't, well...I love my TL-S but I must say that in some areas, my POS Tahoe outpoints it--heck, it has autodimming side mirrors and a more potent butt warmer...did I mention that it has power lumbar adjusters?

Never mind, I should just extol only the TL-S virtues...sorry...

Tony

pianoman41

The difference is the *when* the mirror dims. Your Tahoe (I'm guessing somewhat here based on your description) dims the mirror when it gets dark out, based on the photocell on the mirror. It doesn't matter if there is no one behind you--the mirror is always the same darkness at night. On a dark street with no one behind you, if you look out your rear view mirror it's very tough to see out because the mirror is dim and there is a lack of light.

With the Acura system, the mirror dims only when two conditions are met - (1) It's dark out and (2) someone is shining headlights on your mirror when it's dark out. Now during the day you will see *some* dimming as the front sensor can be fooled and will slightly darken the mirror. *But* the big difference is on the dark street, where the Acura mirror will be brighter because it doesn't dim when there is no light shining directly at the mirror, regardless of the exterior light conditions.

And no, the side mirrors did not autodim.

tdoh

pianoman41--you may very well be right-on with your explainations; however, from personal observation the Tahoe mirror gets dim only when it picks up headlights at close distance. I know this because at night I can still clearly make out the outline of vehicles behind me at approx. 5-6 car lengths but when they get closer than that, all I see is a blur of an outline (if at that), with the autodimmer making the headlight glare a bit fainter.

As far as seeing some dimming during the day--I guess it depends on how one would define "some". At least in my TL-S the difference is night and day as far as being able to tell whether or not the autodimmer is doing its function, because during the day the rear window takes on a clearly noticeable light-bluish tint when the autodimmer is on, regardless of where the sun is at (front/rear/sides/overhead). It's almost as if you were looking at a lightly tinted rear window.

Tony

rock

Sometimes the dimmer isn't all that great. When it darkens, I can't tell if that's a police car following me, unless I recognize the headlights

davest

I'm sure my mirror dims in the daytime and I'm glad it does. I drive West in the morning and East in the evening and I can tell you that the when the Sun is just in the right position, it really shines through the back glass. But my rearview dims it down so it's tolerable.

davest

Now that's something I didn't know! So when you put the car in Reverse, the side mirror tilts down and the auto dimming rearview mirror shuts off--cool!

Thanks RR

gohawks63

With the comparison going back and forth on the Tahoe vs TL dimming mirror. I think both cars do the same thing but it's being lost in the explanation.

I see no practical purpose for the rear view mirror to dim at all when there's enough sunlight outside that people don't have their headlights on (DRLs notwithstanding, but they're not as bright as full-on low beams anyway, or at least shouldn't be).

The TLs mirror does not NORMALLY dim during the day. The only time I've experienced it during the day is when my car is in a dark garage with the door open. This scenario simulates a nightime situation where it is dark outside and a bright light source is behind you (read headlights). If you put your hand over the photocell in front (the one facing the front of the car), it simulates the same thing. I have never experienced my mirror dimming during the day with someone having their headlights on.

tdoh

The TL mirrors may very well not normally dim during the day but I do know that with the autodimmer on (it had never been turned off practically since day one until just recently when I started experimenting with the autodimmer switch) I noticed that at any time during daylight the rear window definitely took on a light-bluish tint when viewed at through the rearview mirror. The mirror may not be dimming, but it is definitely doing something in broad daylight, continuously. The only time that the rear window didn't look bluish during the day was when I turned off the autodimmer. So, what would you call this phenomena if it's not considered dimming in the normal sense of the word?

Tony

gohawks63

So, what would you call this phenomena if it's not considered dimming in the normal sense of the word?

Again, I would say that it's reacting to the differences in light in the cabin and outside. I can't conduct an unbiased test since my windows are tinted.

daverman

Yah, I've seen this happening, usually when the sun is behind me (i.e. the front side of the mirror is in the shade). Doesn't bother me too much. I can still see quite clearly although the mirror has that bluish tint.

Makes it look like everyone's got HID's behind me!