Hagar

I'm wondering if my auto dimming mirrors are actually working and how might one really tell?

I know my 04 UL needs the side rear view mirrors to be in "AUTO" to work and for the rear view mirror, you press the button and a green light comes on to tell you its working. But I watch these things and honestly, I can't see a difference or is it so subtle its hard to tell?

And what is that sensor in the middle of the dash just under the windshield?

Mobius1

The Auto-Dimming function of the mirrors wont work unless the vehicle is in low light or dark conditions. The sensor in the middle of the dash by the windshield vents is the light sensor for the mirrors and Automatic lights.

You can cover up that sensor with a hat or something and test your mirrors out. You should be able to tell that its dimming as the entire mirror becomes dark blue-ish black. Keep in mind all mirrors are supposed to dim (driver side, middle, and passenger side mirrors)

If you cant tell the difference, then it MIGHT be malfunctioning. I know my driver-side mirror doesn't dim anymore. Although i will say this, compared to my last 2002 Isuzu Axiom i had with auto-dimming mirrors, the LS430 is much less effective and might be harder to tell if its working or not. But still noticeable enough to tell that "its dimming".

Hagar

I think I figured out a way to tell if they are working. I know mine are now.

I took a flashlight and shined it into the rear view mirror sensor. That little oval opening on the front and with the switch on, sure enough the mirror dimmed like magic. Now the side mirrors were a little more difficult to see but, yup they dimmed and undimmed as I turned the flashlight on and off. Oh ya, I did this at night and the sensor kinda makes sense where it is now.

From the manual - When the inside rear view mirror darkens in “AUTO” mode, the
outside rear view mirrors also darken to reduce the reflection
of the headlights of the following vehicle. For details, see
“Inside rear view mirror” on page 233.
(Funny how I thought this meant the side mirrors had to be in "AUTO" NOT.)

I think the senor in the middle of the window by the window is for Turning on the headlights only. From the owners manual - "The automatic light control sensor is on the top center of the instrument panel."
instrument panel.

Johnhav430

They really do get very dark, and if yours is worn out like my pass. side, you see weird sections which do not get dark, because the gel is messed up. A really great feature, that and the rain sensing wipers, but I still don't seem to be able to pay the $186 on eBay for a new mirror glass...

mannye

Super easy if you have a sunshade for your windshield. Just keep the car running, park in a sunny location and place the sunshade on the windshield. In about 10 seconds your headlights will come on and about two seconds after that, you will see the rear view mirror turn a deep dark greenish "smoke" color. If it doesn't, it's not working. Or it could be off. Make sure the button on the mirror is pushed.

CA2WALS430

I just replaced my passenger mirror glass and housing, 100% OE from Bell Lexus. I am confident the mirror is not dimming. I back out of my garage and the drivers outside mirror is the blueish tint color and passenger mirror is unchanged. All other functionality seems to be perfect though I have not been able to test defrost yet.
Does anyone have a theory here? Here is part code I ordered for the glass: 8793150460
I do see supercessions in the part codes. Is it possible this new code does not dim?? Why would they not do that?
I will email Bell, but thought I would hit up the pros here first.

CA2WALS430

I spoke to Bell Lexus today. They confirmed that is the right part number and that auto dimming is not mentioned in the specs. That sucks. I have submitted a complaint about the part code to Lexus Customer Service. I will update here when I have some resolution. Oh boy, I am not going to back off of this one easily. When we pay the exorbitant price for OE, we SHOULD GET OE!!!
The dimming feature is huge, especially with the wretched LED/HID headlights on cars now.

aypues

That really sucks. Yes please keep us updated. I just replaced my driver side mirror housing bc the auto motor broke and just reused the mirror glass thankfully. That glass isn’t cheap!

CA2WALS430

Thanks, @aypues ,always enjoy reading the things you do for your car; you are more tenacious than I am.

The result is this for any who read. This mirror glass is actually fully functional. The hue is different than the original, and that is a big quality miss, so when I am sitting in my garage in the morning, the driver's mirror is the original blueish hue and the new mirror is a more goldish hue. Last night I was on a busy road for a long time and glanced at both mirrors a lot. Headlights were almost equally muted, with exception to the original being more effective with the blueish hue.

Anyway, I wrote Dan at Bell and he said he will certainly pass the feedback up the line to the reps. I think he gathered from my passion that it's real. That is about all that can be done. They work, but they are not fully OE. I work in Quality and Regulatory for a living and I just know that you can't go through that many part supercessions and maintain the quality control. It's a bummer, but kind of the new normal too.