Heated Mirrors - PeachParts Mercedes-Benz Forum

C Holmes · #1 12-19-2009, 05:31 AM

Hi All, While doing a body job on my 87 TDT I realized the car has heated side mirrors. I assume this anyway because of the power wire going to each one. There is power there to the mirror ( all the time ) I assume there must be a thermostat to turn them on and off. My mirrors have never worked since I owned the car but I would like to have them working. Is there any ways to repair them? Any of the parts on the mirror replaceable, thermostat for instance?

C Sean Watts · #2 12-19-2009, 12:00 PM

The elements are supposed to work (on and off) with the rear defroster, according to my manual. But, mine have not worked for a long time either.

C Holmes · #3 12-19-2009, 12:25 PM

Well I dunno, there is power all the time to the mirrors regardless of the rear defogger. I know my S Class works with the rear Defogger but the 124 I think may be different.

C Sean Watts · #4 12-19-2009, 12:42 PM

Quote:

Originally Posted by C Holmes

Well I dunno, there is power all the time to the mirrors regardless of the rear defogger.

I think you figured out why they do not work. Since they are NOT supposed to be on constantly, you have a bad relay or switch. Also, measure the resistance in the mirror element circuit. My guess is you'll have a very high or infinity (open) circuit.

IF you have the USA model you might have a stuck relay that is driven from the OAT probe. If the OAT probe has been removed, or doesn't work properly, then there's the problem.

IF you have the Euro model (a lot in Canada at that time were) it's connected to the defroster and should cut off after 20 minutes or when the current demand too high. Start it up, turn on all the electrical accessories THEN turn on the rear defroster and watch for the indicator light inside the switch to start blinking. THEN measure voltage output to the mirror heaters. If the switch does not blink or the voltage doesn't drop, check the switch and relay.

Jeremy5848 · #5 12-19-2009, 12:54 PM

The mirrors in the 124 are thermostatically controlled; the thermostat is supposed to close below 50F or 10C, more or less. The mirror, heater, and thermostat are all one unit. The thermostat is not separably replaceable.

Using padded pry tools, it's fairly easy to pop the mirror out of the housing, unplug the two-wire connector on the back of the mirror, and remove it to your bench. Put the mirror in your household freezer for awhile (or lay it in a pan of ice) and the thermostat should close. You can then apply 12 volts and the mirror face should warm up to the touch, until the thermostat warms up and opens. If you cannot get that to happen, then the thermostat is bad or the heater wires have failed open.

A new replacement is beau coup bucks, over CDN$100 at a dealer. I bought a spare for each side of my '87 from the local Pick and Pull for US$4 each because their computer doesn't differentiate between "mirror, glass only" and "mirror, Mercedes, heated, expensive."

See Spare mirrors -- good to have for pictures.

Jeremy

Sev · #6 12-19-2009, 01:08 PM

Quote:

Originally Posted by Jeremy5848

The mirrors in the 124 are thermostatically controlled; the thermostat is supposed to close below 50F or 10C, more or less. The mirror, heater, and thermostat are all one unit. The thermostat is not separably replaceable.

Using padded pry tools, it's fairly easy to pop the mirror out of the housing, unplug the two-wire connector on the back of the mirror, and remove it to your bench. Put the mirror in your household freezer for awhile (or lay it in a pan of ice) and the thermostat should close. You can then apply 12 volts and the mirror face should warm up to the touch, until the thermostat warms up and opens. If you cannot get that to happen, then the thermostat is bad or the heater wires have failed open.

A new replacement is beau coup bucks, over CDN$100 at a dealer. I bought a spare for each side of my '87 from the local Pick and Pull for US$4 each because their computer doesn't differentiate between "mirror, glass only" and "mirror, Mercedes, heated, expensive."

See Spare mirrors -- good to have for pictures.

Jeremy

you learn something new every day...

MattBelliveau · #7 12-19-2009, 01:12 PM

Was this standard on most w124s? I never noticed this on mine...now if I could only add heated seats...

Sev · #8 12-19-2009, 01:19 PM

forgot to mention, on w124's, they all had heated mirrors. even the most poverty of poverty models. before the w124 came out, some 190e's were reported to not have them. but all 190e's with the w124 mirrors (after 87) had them for sure

Jeremy5848 · #9 12-19-2009, 02:32 PM

Quote:

Originally Posted by Sev

forgot to mention, on w124's, they all had heated mirrors. even the most poverty of poverty models. before the w124 came out, some 190e's were reported to not have them. but all 190e's with the w124 mirrors (after 87) had them for sure . . .

I'm amazed at how many 124 'features' first appeared on the 1984-85 201 models. The 1986 W124 "Introduction into service" manual, which includes the 300D Turbo, in many places refers the reader to the 201 model in the "Introduction" for an earlier year. In 1986, the chapter on the 603 engine is specifically entitled "Modifications as compared to engine 601."

For example, the electronic idle control is "known from engine 601 model year 1985" (i.e., the W210 190D 4-banger diesel). The OM603 engine is mostly an OM601 with two more cylinders and a turbocharger; many of the bits and pieces crossed over to the bigger engine without change (good to know at the junkyard!).

Another similarity is in the instrument cluster: "The indicating instruments and lamps are functionally the same as on model 201 model year 1985." However, "an exterior lamp failure indicator has been added" so the 124 does have some changes, additions, and improvements over the 201.

It can be frustrating for us late-comers that Mercedes doesn't repeat things and assumes you have a complete set of all Mercedes manuals.

For the 1987 300D Turbo, that means at least back to the earlier 300D (W123, OM617). For example, the EGR computer and OVP relay from the 1985 300D-T are also used on the 1986-87 300D Turbo. The computer has a different part number but the function is the same except for the addition of electronic idle speed control of the 1986-87 IP. Similarly, the ALDA, engine overload protection, and fuel rack position sensor from the OM617 engine were carried over to the OM603 engine. All of these descriptions tend to show up in the "Introduction" manuals and often nowhere else.

Caveat: Later W124 models (300D 2.5, etc.) definitely had many changes. My comments are strictly applicable only to the 1986-87 300D Turbo. YMMV.

Jeremy

Sev · #10 12-19-2009, 03:05 PM

Quote:

Originally Posted by Jeremy5848

...so the 124 does have some changes, additions, and improvements over the 201.

Jeremy

i used to resist these comments since i was such a 201 fanboi, but having completely disassembled (almost every bolt off of) both a 201 and 124, and having driven models of both chassis, i can say for sure the w124 is a superior car in its stock form--definitely improvements in every aspect

Crazy_Nate · #11 12-19-2009, 03:17 PM

Quote:

Originally Posted by Jeremy5848

The mirrors in the 124 are thermostatically controlled; the thermostat is supposed to close below 50F or 10C, more or less. The mirror, heater, and thermostat are all one unit. The thermostat is not separably replaceable.

Using padded pry tools, it's fairly easy to pop the mirror out of the housing, unplug the two-wire connector on the back of the mirror, and remove it to your bench. Put the mirror in your household freezer for awhile (or lay it in a pan of ice) and the thermostat should close. You can then apply 12 volts and the mirror face should warm up to the touch, until the thermostat warms up and opens. If you cannot get that to happen, then the thermostat is bad or the heater wires have failed open.

A new replacement is beau coup bucks, over CDN$100 at a dealer. I bought a spare for each side of my '87 from the local Pick and Pull for US$4 each because their computer doesn't differentiate between "mirror, glass only" and "mirror, Mercedes, heated, expensive."

See Spare mirrors -- good to have for pictures.

Jeremy

Bookmarked! I'll make sure to test mine when I get the new ones in

The current ones are pretty scratched, I'm not sure what happened, it's not on the surface... I'm sure I'll have pictures

Jeremy5848 · #12 12-19-2009, 03:32 PM

Quote:

Originally Posted by Crazy_Nate

. . . The current ones are pretty scratched, I'm not sure what happened, it's not on the surface... I'm sure I'll have pictures

Not sure about scratches but I have had problems with water spots on Mercedes outside mirrors. So far, the best thing I've found is the polishing compound sold for cleaning the ceramic 'glass' used in fireplace inserts and stoves. One such product is Rutland's "White Off" made in (of course) Rutland, Vermont. It still takes a lot of rubbing; I'd like to find a chemical that would just soak the water spots off but then again I don't want to dissolve the car in the process.

Jeremy

C Holmes · #13 12-19-2009, 03:45 PM

So I gather that power is supposed to be at the mirrors constantly

tbomachines · #14 12-19-2009, 04:56 PM

I believe the 126 mirrors are thermstatically controlled as well but I'm hoping someone can confirm this...mine are both cracked down the middle so nonfunctional...

Jeremy5848 · #15 12-19-2009, 05:11 PM

I just discovered that the outside mirrors (on the W210, at least) are "first surface" mirrors -- the reflective coating is on the outside of the glass. As any astronomer will tell you, this is great for reflection control but not so great if, in your enthusiasm for removing water spots, you polish through the reflective coating, as I just did.

My "wanted" notice appears in the Parts section of this forum.

Jeremy

PS -- Holmes, the mirrors have power anytime the key is on. In the '87 300D Turbo, fuse "B" controls.