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Discussion Starter · #1 ·
I'm STILL not sure if the dimming feature on my rear-view mirror is working (2005/pkg 6).

The light on the mirror suggest that it's on. But, when I compare the headlights from a car behind in the rear-view with the side—they look to be identical.

I put my finger over the sensor on the back, and it does nothing.

Any suggestions?

Thanks,

marlowe
 

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take a torch (flashlight) out at night (or in your garage). Go to IG-ON so that the mirror is on. Cover the rear sensor and shine the torch at the mirror and see if it dims.

If it works, rotate your mirror upside, taking care not to twist the wires. It should work better.


What's hindering its function is the rear spoiler.
 

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Discussion Starter · #4 ·
mirror dimmer (again)

Reading you post again, very little of it made sense to me.

Why would the spoiler hinder the mirror's function? I know the difference between a headlight blocked by the spoiler—and not. I'm talking about when the headlights are clearly in the mirror.

Also, I can't see any physical way possible to turn the mirror upside-down. You would have to remove it entirely to even have a chance to do so.

As it happens, I think the mirror is working. I did your trick with the flashlight. BUT, it's not the rear sensor that does anything. It's the sensor on the front of the mirror (next to the on/off button. When I block THAT sensor, the mirror changes to a greenish tint.

Anyhow, bottom line is I guess it's working. It's just that when I'm driving at night it doesn't seem all that dim.

Oh well, there are worse problems to have.
 

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Look at it again.

Notice the sensor is not in the middle of the mirror's surface; just because you see headlights in the mirror, that does not mean the sensor sees them.

Also, you rotate the mirror to flip it. Just choose clockwise or counterclockwise so that you don't yank the wire. One way will allow rotation without any stress on it.

Lastly, notice there are two ball joints in themount, allowing you to raise or lower the mirror. Find a position higher up towards the roof.

These two steps have almost entirely solved the "non-responsive dimmer" problem for me.
 

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The headlight may be visible to you, but it is if the headlight is visible to the sensor that counts. I don't know if I agree with it but the theory is that the spoiler casts a shadow of itself onto the sensor making the mirror think that there is no glaring headlight problem.

Which brings me to the other point you made that makes no sense. The mirror dims if the light seen by the sensor on your side of the mirror is brighter than ambient light seen from the backside sensor facing the windshield.

On a bright day as I pull out of my garage, the mirror dims because it sees the garage as almost night (windshield sensor facing the back of the garage) while the bright daylight pouring in from the opened garage hits the detecting sensor facing me. If I cover the sensor on my side, it lightens, and when I pull out, daylight hits the windshield side sensor thus disabling the dimming effect.
 

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Discussion Starter · #7 ·
Okay, Dan, I get what you're saying about the front and rear sensors.

Still don't see any possible way (or reason) to turn the mirror upside-down, but I'll leave that for now.

It's strange, though...when I did the test last night with the flashlight, it definitely dimmed to a greenish glow. But, again, when driving the night before, I could see no difference between the lights in the rearview and the lights in the sideview. I'm assuming the sides don't have a dimmer, right?
 

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correct, the side-view mirrors on the Prius do not have auto-dimming. The side view mirrors have heating though. I am not sure if the heating function is only in certain packages.

Dimming can be subtle at times, and I also find if I haven't washed the car in a while, where the rear windows are dirty, the mirror dimming effect is diminished.

To put the mirror upside down, turn (spin) it in a clockwise (or counter-clockwise) direction, as if adjusting it for proper angle, being careful not to strain the wiring to the mirror.

Another reason the mirror might not dim is that streetlights are too bright, tricking the system into thinking that it is daylight or twilight. The solution here is to tape the forward viewing sensor with black tape, dark translucent tape, or dark tinting.
 

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Re: mirror dimmer (again)

marlowe7 said:
Reading you post again, very little of it made sense to me.

Why would the spoiler hinder the mirror's function? I know the difference between a headlight blocked by the spoiler—and not. I'm talking about when the headlights are clearly in the mirror.

Also, I can't see any physical way possible to turn the mirror upside-down. You would have to remove it entirely to even have a chance to do so.

As it happens, I think the mirror is working. I did your trick with the flashlight. BUT, it's not the rear sensor that does anything. It's the sensor on the front of the mirror (next to the on/off button. When I block THAT sensor, the mirror changes to a greenish tint.

Anyhow, bottom line is I guess it's working. It's just that when I'm driving at night it doesn't seem all that dim.

Oh well, there are worse problems to have.

well, I guess the others answered most of your concerns here.

The reason why I said the rear is because the rear sensor is the one that checks ambient lighting. The front (next to the on/off switch) is the one that senses the headlights.

To rotate, make sure that your mirror is moved to the lowest position, vertically (i.e., don't just tilt it down, physically move it down.) Then I suppose rotate it, tilting if necessary. What KTPhil said, there are two ball joints allowing the tilt and the up/down adjustment.

Heated mirrors should be standard on all packages, Dan.
 

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Okay, Dan, I get what you're saying about the front and rear sensors.

Still don't see any possible way (or reason) to turn the mirror upside-down, but I'll leave that for now.

It's strange, though...when I did the test last night with the flashlight, it definitely dimmed to a greenish glow. But, again, when driving the night before, I could see no difference between the lights in the rearview and the lights in the sideview. I'm assuming the sides don't have a dimmer, right?
Well, if you are driving in town where there are street lights then the mirror "sees" the street lights as brighter than the headlights behind you, and doesn't dim. I've had a dimmed mirror "un-dim" when I came around a curve and there was a street light. Oncomming headlights do the same thing.
 

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Discussion Starter · #11 ·
mirror dimmer (again)

My old Corolla had the old-style, manual mirror where you simply flipped it into the dimming mode. Simple, and worked perfectly.

This, I think, is one of those things that the fancy technology made a bit worse. Some things are best left alone.

However, the Prius is entitled to a few minor shortcomings!
 

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"Still don't see any possible way (or reason) to turn the mirror upside-down, "

Well, we told you how and why. What's more to explain? As Nike says, ...
 

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Re: mirror dimmer (again)

marlowe7 said:
My old Corolla had the old-style, manual mirror where you simply flipped it into the dimming mode. Simple, and worked perfectly.

This, I think, is one of those things that the fancy technology made a bit worse. Some things are best left alone.

However, the Prius is entitled to a few minor shortcomings!
Well it works fine in our Camry without a rear spoiler and hence direct line of sight to the trailiing vehicle. This is why I can say it's not the mirror's fault but the design of our rear spoiler and split tailgate.
 

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I had a piece of 20% mirror tinting film applied over top of my standard rearview mirror and it's perfect in all conditions, day or night.. During the day, you don't really notice a difference; at night, you get an adequate reflection of everything (unlike the "night mode" mirrors where you can't see anything, or you see the reflection of the ceiling or your back seat instead of the outside world), but headlights are cut dramatically- I can have a big truck behind me with high beams on and it doesn't bother me..

This is a totally passive solution that cost next to nothing and there are no tabs or switches to fiddle with..
 
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