C230 Sport Coup

Anyone have any technical info on the self dimming mirrors?
What controls them? Is there any sort of reset?
I thought mine had stopped working entirely, but this weekend discovered that in fact they are working albiet incorrectly.

I took interest in noticing that in fact there are two sensors on the rear view, one front, one back.

They seemed to operating exactly opposite of that they should, getting dark when the surroundings got dark as I decended into some Redwoods,
then getting lighter, as the light increased.

At one point the inside mirror was so dark, you couldn't see behind the car.
Placing my fingers over the front or rear sensor resulted in all kinds of
interesting responses.

So, I'm happy to see they might still be working, and perhaps are in a state that can be repaired,
but sadly I don't know where to begin?
Does SDS read anything on this?
IS there a reset, like hold down a button for 5 seconds or something?

C230 Sport Coup

As usual I'll probably provide more info than I'll get, but perhaps with these documents, someone like Glyn might have an intelligent answer.

It seems that while the whole thing is done via the CANBUS, the dimming itself it actually controlled by a module in the front door.
Who woulda thunk it?

C230 Sport Coup

Well, interestingly it says in one of those docs, that when you either turn on an interior light or put the car in reverse a special wire that goes from the overhead control panel sends a signal to un-dim the interior to the maximum birhgtness, while leaving the outside mirror alone.
So here's an associated doc on the overhead control panel.

samaritrey

Wish I could help and tell you how to fix it but I have no clue. That said if you need me to look at something with das let me know and I can check for you.
I love how complicated these cars are vs normal cars. Connecting the mirror dimmer to the front door computer seems a little crazy to me even if it does have a cool function.

Moviela

The mirrors have a gel inside that is optically clear when no voltage is on the gel. As the voltage is increased, the gel gets darker. The interior mirror has all the smarts to read the sensors, the reverse and interior lighting signals, and apply the voltage to the glass. It also sends the dimming information to the CANbus b. This is read by the door module. The door mirror is a dumb device, and reacts only to signals from the door module. The door module has circuitry similar to that in the interior mirror to send a voltage to the door mirror glass.

It is done this way to save weight and copper wire connecting various systems.

If your system is reacting opposite the desired operation, and both mirrors are reacting the same way, you have a defect in the interior mirror. The sensors or the amplifiers for them may have lost the war with the heat suffered by the interior mirror being high inside the car and near the window.

I have not seen any adjustments available for the circuit through STAR. I would think that the assembly would be trimmed during production to allow for the wide variation in spectral response for the sensors used.

You probably need a new mirror assembly.

Glyn M Ruck

The mirrors are basically a LCD.

Moviela

The elecrochromic mirrors on most cars are not LCD's. The working optical component of the mirror is tungsten oxide. The electricity creates an oxidation of the WO3 in the lithium electrolyte gel. It has an adjustable range, depending on the current flowing. LCD's and not very adjustable being either open or closed.

The gel is acidic, and you should be careful not to touch it if it leaks or the glass is broken.

C230 Sport Coup

That's it?
That the best you can do? Mr. Smarty Pants Mercedes Guy,
and that's all I get?
Really?
Perhaps you are slipping? Durp Durp Durpie Durp, it's an LCD errr...hrrrrrrr
Advanced age can do that to people, or perhaps you need to stop drinking the cheap stuff.
Invest in a good bottle of wine and get back to me.

Glyn M Ruck

Movie gave you all the rest. Benz claim their mirrors are LCD ~ at least on the CLK. Rudeney on the W209 forum confirms this. ????

If the mirror does not react to having a current applied to it then replace it.

Glyn M Ruck

Now I'm confused. In some of the literature Benz talks of LCD & others they talk about an "electrochromic element in the mirror". I think they use both as they generate pictures in some interior rearview mirrors.

Glyn M Ruck

No fine Cape plonk today.

Tomorrow evening have invited the neighbours to dinner at my favourite local Thai restaurant. Promise to only consume SA's best.

Stop being cheap ~ replace the darn thing!

samaritrey

Wow you guys are mean leave the old man alone.

Moviela

May I suggest from Groot Constantia some 2010 Grand Constance. This golden elixir is perfect with the complex flavors of Thai cuisine. It is worthy of being SA's best.

Glyn M Ruck

Ah yes you may! The winery is just over the hill from me. Good call ~ Platter's 4.5 star and another Gold award. It is delightful.

mtnman82

c230 - I've noticed if the rear facing sensor has more light than the forward facing sensor, it will dim the mirrors. This would be the scenario if you were driving at night and someone with bright headlights was driving behind you - you'd want the mirrors to dim. Just a tidbit, but hope it'll help some. That's why there's that special wire for the interior mirror too.

I thought mine were messed up at first, until I realized I was only noticing weird things when I had would take the sunshade on or off (blocking the light to the front facing sensor wrt the rear facing sensor).

For a simple test, I would think a flashlight shining into the front facing sensor would un-dim them and a flashlight into the rear facing sensor would dim them.

jkowtko

C230, did you ever fix this?

My rear and left side mirror tend to dim almost all the time during the day. Sometimes if I cover the sensors I can get it to change, but most of the time it's not responsive, and they seem to have a mind of their own.

It looks like I cannot simply pull a fuse, because the fuses it uses (9.21) are shared with a lot of other components.

So, what is the cause? Sensors/circuitry in the rear view mirror?

Thanks. John