Double taillight bulbs for the W124 (DIY w/pix)
 

WHY it took me so long to realize that my 1987 300D Turbo had an "extra" tail lamp socket I cannot explain. I had added an extra lamp to my 1985 300D-T (W123, OM617) a couple of years ago, following a thread on this forum. Is my mind going at last??? :eek:

At any rate, while at Pick and Pull last week, I checked the trunk of the 1992 300E I was working on and found the bulb carriers sitting loose – someone had pulled them out and left them lying. I saw that the left side had an extra bulb that the right side did not have. This, of course, is the rear fog lamp that European models have, which was apparently introduced to USA versions during the W124 model run.

Checking my '87, I found that the bulb carriers had an extra hole but no center contact. However, everything else was there and all it needed was to rob a contact from another carrier and put it in mine. Here's how I did it.

After removing the bulb carrier from one of your taillight assemblies, unplug the electrical connector and take the carrier to your workbench. The left carrier may have a foglight contact (and bulb) or not, depending on the year of your 124. See the first two pictures.

Remove the bulbs from the lower section and carefully pry out the metal strip (the plastic tabs break easily). If your car already has a center contact at the innermost position, all you have to do is rewire it. If not, you'll have to install a contact and wire it to the existing tail light contact. The third and fourth pictures show how to do this.

Now reassemble the carrier by snapping the metal strip into its tabs. Make sure the section by the side marker light goes into the slots in the plastic. Put the bulbs back in place. The two tail lamps and the side marker lamp all take 10W bulbs while the reverse, brake, and turn signal bulbs are all 21W. Now plug the electrical cord in and return the bulb carrier to its home in the taillight assembly. Turn the light switch on and test your work. Repeat for the other side. You're done.

Warnings
(1) It's important to not increase the size of the tail lamp bulbs – you have already doubled the power that the tail-lamp-control electronics have to handle.
(2) The "Exterior Lamp Failure Monitoring" device will no longer register a single tail lamp bulb failure, since you now have two bulbs on each side. Both bulbs on one side must fail before the system will realize it.

I'll post "before" and "after" pictures tonight when it gets dark enough for the lamps to show.

Jeremy

Yes they are rear fog. The 124 US cars got them starting in MY1990, including the 8-pin connector and proper switch/bezel with indicator light.

On the wagons, with no rear fog lights (some USV models had them), the blank slots can be used for another brake light mod, this time with the S124. My mechanic did this on his 89 TE. Similar concept. Just don't break the tabs for the tail light assemblies, they get quite expensive.

It should be as easy to use the holders for extra brake lights. Just need longer wire. The lens housing should accept a brake light bulb since the rear fog uses the same bulb.

Sixto
87 300D

Light work
 

My concern would be overloading the electronics upstream. Going from 21 to 42 Watts in each brake light circuit might cause an overload. No guarantees, I would be happy to be proved wrong, just concerned.

Here are pictures of my car "before" and "after," taken late this afternoon.

Jeremy

Excellent writeup Jeremy, thanks. The upgrade really provides a better, more visible and safer taillight. Anything to get someone who's makin love to their cell phone's attention is a good thing.

I hope it all goes well. I want to do this as well to my w124.

On my w123, since I performed the same upgrade, every once in a while, the no.12? fuse blows. Like maybe 2 or 3 times a year. I blame it on the modification as I didn't have the problem prior to that. Did this happen to you on your w123?

At any rate, thanks for taking the time and pics to share.

No, I've had no problems with the extra taillights blowing fuses in my '85 300D-T. I would check the fuse to make sure it is the correct size and then check the tail lights to make sure the bulbs are the correct wattage. The only other thing I can think of is something that would occasionally cause a short circuit, like a wire being pinched against a sharp piece of metal.

I doubled the brake lights on my 300SD AND added a LED third brake light at the top of the rear window (also did this to both of my dad's SD's)....I've had no fuse or wiring issues with it.

On our 300D I put in 27 watt brake light bulbs instead of 21....so they are a bit brighter.

Our 300E is a 1990.....so apparently it has the fogs lights already....I wasn't even aware of this. I'll have to check it out. :D ....and let the wife know its there.

Just driver's side Paul. The 201s and 126s also I believe starting MY1990, and the 124 wagon/T124 got the rear fog in 1990.

Pull the headlamp switch out two notches, first is front fog, second is f&r fog with the orange dot in the switch indicating rear fog light.

It's too bad they never sold the W126 here with a factory rear fog lamp :/

-Jason

You sure? I thought the '91 had a rear fog, ... I'll have to check mine (still have the taillamp holder and switches).

The 1993 300E 4-Matic that I got my extra parts from did have the fog lamp installed in the left taillight assembly only. It also had an 8-pin plug/socket (with 7 pins provided) with an extra wire for the fog lamp while the right side had the usual 6 pins.

Our 1990 300TE did not have rear fog lights, neither did it have a slot just awaiting a new bulb.

The 1993 190E does have a driver side rear fog light. I think it was around that time.

I know some 2nd gen w124's had rear fogs, and some didn't. Perhaps almost all 3rd gen (1994-1995) w124's had rear fogs.

I know my '91 300TE 4matic had a rear fog, I guess the wagons didn't get it until '91 then?

Oops, it was a 1992 300E 4-Matic that I got the parts from. It had the rear fog light.