My centermost taillights don't work
 

I had one of the taillights assemblies out while I was doing bodywork and noticed that there was not any socket in this taillight.

Kinda weird.

That is normal for US 123s.

The socket is for the rear high intensity fog lamp that is actuated when pulling the light switch out to the second stop. If you pull the knob off you will notice a light socket there, that is supposed to light up with the knob pulled out to the second stop and makes the hub of the switch knob glow orange.

The Feds don't like that feature or at least they did not back in the 80s so the US models were not equipped.

I think several members have added extra brake/tail sockets salvaged from a parts car and wired in parallel to the other brake/tail bulb. On a 123 that is a good thing given there is only one brake light per side and no CHMSL.

Or you can get hold of the Euro wiring diagram and hook up the rear fog feature. I believe the US light switch has the necessary contact and the indicator bulb socket in the knob stem is active. It uses the same type bulb as the turn signal. This goes on the road side (left for US), the other side remains blank.

upgrade!!! It's the way to go....add the sockets and get more brake lights
 

I performed this upgrade on Coda and have the parts for the 87 Champagne. Here's the write-up done by Chad:
http://www.peachparts.com/shopforum/diesel-discussion/287882-brake-light-upgrade-w123.html

i did the upgrade on my 83SD. will the upgrade affect the operation of the bulb-out light on the GEN 2's? i want to do the upgrade on my 91 SEL but wasn't sure...

Hmm, I'm not sure that will work, the relay is probably calibrated for the draw of one bulb. If you put 2 in parallel that is double the current. Not sure what the relay thinks of that.

If it accepts double the current and still gives a good indication then you would have to lose both bulbs to get a fault. But I'm worried you might smoke the sensor in the relay with double load.

I'm pretty sure every bulb on the outside gets its own channel in the bulb monitor.

I added extra brake lights to these spots, on my 300D w123.

http://farm5.staticflickr.com/4053/4...c98512ff_z.jpg

Some members have modified theirs to function the same way Euro w123's do, by adding a rear fog light in the tail light on the same side as the driver, and wiring it up.

However, my observation is that on some units these innermost lenses do not have a proper reflector to bounce off the 21W brake lights, but some do. What happens is these spots will appear slightly darker due to less reflected light.

I did the brake light up grade several years ago on both my 123 sedans.

I really don't have that much interest in adding a brighter fog tail light. but wouldn't mind adding either more regular taillights, brake lights or turnsignals. I think having an additional brake light might add the most safety.

Thanks.

I did the up grade before discovered the forum. wonderecd why there was no light on each side. got a broken light from a junk yard and canablised some socket and soldered them in.

It sure lights up the night sky. :D

There was a thread last year of an up graded brighter bulb, Iam going to do a search and post it. 10-23. (standby)

Found it.


http://www.peachparts.com/shopforum/diesel-discussion/297456-%246-brighter-w126-brake-lights.html

Charlie

I tested the main light switch on the way home. There is a second "out" position on it. Of course without wiring....

The second detent, as called in the manual, is for rear fog lights. European and rest-of-world models had them. US models did not.

yeah that's what i was worried about. maybe if i wire-in a diode it might be ok; not really worried if one of the "upgrade" brake light bulb goes out and the indicator doesn't show it...