Late last night (or early this morning) I was coming back from LA and driving up a very wet I-5 @ around 4000 feet elevation. The temp display shown below freezing. It was very useful in determining icy conditions and hit several slick spots. But took precautionary measures... Basically slowing down and paying attention more.


Great instrument to have!






On a side note. I've found the w124 type of temp display fits better in the cluster. I will add a post about this a bit later.



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1983 123.133 California
- GreaseCar Veg System

Hmm, I just picked up a 124 display too. It reads in F. I know what the 5 wires do, so maybe I'll install this one instead.

Find a one watt 3 ohm resistor (3.2 ohm?) and put it in line. This should drop about 2 volts and dim the light appropriately. Then it will dim with the rheostat and look more appropriate at night.

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mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

Here are some pics of the w124 display being installed.

Comparison between the w124 and w126 temp display. The w124 display is obviously shorter.


Had to add new screw holes to match up with the w123 cluster. Drill is positioned in the new location.


W124 temp display fitted in the W123 cluster.



Compared to w126 display as installed.



This picture is how to wire up the 5 pin connector. Later year w124 displays uses this type. The earlier years display uses the 4 pin connector found on the w126.

To install the wire, it is similar to what I shown earlier in the thread but with the following....

#1 pin has two ground wires. One for temp sensor/probe and the other for ground connection to the body.
#2 pin is Illumination power.
#3 pin is Temp sensor/probe signal.
#4 pin is for the later model year w124 specific speed control. You will leave disconnected for use on the w123.
#5 pin is main power.






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Attached Thumbnails

         

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1983 123.133 California
- GreaseCar Veg System

You can use the same wiring and female connectors on the 4 pin plug and transfer to the 5 pin plug housing.


Here is a .pdf doc on a newer w124 retro fit to an older harness. Courtesy of jeremy5848.

http://www.peachparts.com/shopforum/attachments/diesel-discussion/68669d1244610680-w124-outside-temperature-display-wiring-diagram-outside%2520temp%5B1%5D.pdf


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1983 123.133 California
- GreaseCar Veg System

Thanks for the tip! I will try that and report back when I get a chance.

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1983 123.133 California
- GreaseCar Veg System

This thread needs to be in the DIY Articles.

Great Job Richard,


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

How did you get the wires and the connector through that hole? I'm guessing you had to take the wires out of the connector, route them through and then place them back in the connector from the inside of the car?

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Thanks Charlie, But I think it still needs some fine tuning before it being turned into a DIY. I would like to tap into a better power location for the Illumination as well as correcting the brightness with a 1 watt 3 ohm resistor as mentioned earlier. As far as the Illumination power lead, I think pin #12 on the instrument cluster plug wire harness would be a good place to tap into. I'll see if it works a bit later, unless someone else beats me to it.


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1983 123.133 California
- GreaseCar Veg System

Actually when you pulled the wire from the donor car, you have to cut the wire at the connector to pull it out of the dash of the donor car. When installing it, I used telephone wire (or some thin wire) to get through the grommet and then wrap it around the two prob wires. Once secured, you just pull it straight out and then unwrap the telephone wire from it. You will re-solder the connector. I've done this a few times already, one time I just cut the wire in half, sent it through the grommet and used a wire connector to splice them together under the dash. Not sure if it is a good way of doing it as the splice may effect the temp sensor output. But it seems to work fine.


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1983 123.133 California
- GreaseCar Veg System

As far as the 1981 model year but probably most 123 model years, Pin #12 on the instrument cluster is the interior illumination rheostat controlled voltage. If your looking down stream from the pin the wire is GY/BU, gray wire with a blue stripe; the same wire illuminates the ACC panel bulbs, the fiber optic light source bulb and the hazard switch bulb

All this great work begs the question, "Was there anything ever intended for this prime instrument cluster location by Mercedes on the 123?"

Yes! Column shifting auto transmission 123 cars have the gear indicator in this position!

delivery valve: nice job, dude. i've been wanting to do this from day one on my w123. after driving 201's and 124's my whole life, the gauge is almost a must. as i was reading the thread from the first few pictures my mind immediately jumped to the later model w124 temp display which is shorter--i'm glad you eventually swapped over to this new style display. hopefully the cluster fits on the bottom side now.

yeah, this is next on my to-do list along with fitting cluster LED lighting, gauge rings, and fixing my odometer--going to do it all at one time.

as for the suggestion about the w201 temp display, not a good idea. first off those plug into the w201 cluster from the front, and have a wiring harness attached to them, with either one, two or three separate plugs, depending on the year of the car they were removed from. the w126/w124 units are much easier to work with and install from the back of the cluster

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yes, a piece of foam
don't laugh it's a factory part

yeah, on some w116 and w123's, i believe they had a seat belt warning light, or just a colored plastic dummy light strip there. on early w116's, this light was located on the front of the shifter console and had it's own wiring harness and light bulb attached to a plastic housing that said seat belt (same as on w114/115 I believe). it turned off when you plugged in your driver's side seat belt if it had the wiring harness attached to the buckle. on later ones ones, i think it was a film of plastic like the dummy lights that just said seat belt on them, with no light in the background.

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