Original W126 Euro Bosch Headlights
 

Original W126 Euro Bosch Headlights Gen I 4 door. These have the H4 55/60W set. I notice there is another tiny bulb down near the bottom center. Not the fog bulb off to the side. I tested the bulb and it works, but I just can't figure out when it is supposed to be on, it seems to never be on no matter what I am doing with the lights. Is this some sort of daytime running light, or what? Thanks!

Does it come on when the left or right parking lights are on? Just guessing. My 89 has US specs.

On Euro spec cars, the city light comes on in lieu of the running light in the corner marker. Most wire it to the parking lead in the corner light so both will illuminate. Some leave it off, but they're lazy idiots.

The North American spec lights have the turn signal lamps act as side markers when park lights are engaged. The European or rest of world market uses "city" lights inside the H4 reflector housing like you discovered, as the park lights. The turn signal lamps do not illuminate this way and are only used for indicating direction of vehicle travel. Hence the turn signal light is also a single filament bulb on European or rest of world market cars.

You have to rewire the system properly to have them function "correctly" (per Euro spec design). Or you can splice a wire from the turn signal light to the city light (once you figure out the color codes) so both are on. Or just leave them be and use the turn signal lamps as the US DOT intended them.

I tried that, but nada....

This is an original euro - strange that they do not come on. I'll have to check where those wires go. And check the turn signal bulbs. Which bulb # is for which? thanks

Well, I finally got around to looking at the situation closely. First off I am very impressed with the signal light mounting engineering :D out and back in right quick and easy :D That is an original bosch P25-1 and has a crack so I am looking for a replacement.
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Second, I discovered that for both sides the lil bit of flex vac hose attaching to the vertical adjusters were rotted and replaced them. Now I can run those up and down for bird watchin' or turtle squashin'.

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All the wiring seems just fine from the lil city bulb to the plug, and everything seems fine on the other side of the plug. That stuff disappears into a harness and erupts in the bottom of the fuse box and I didn't take that all apart to investigate.
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Three wires come out of the signal plug and cross over into the bundle from the headlight plug. Every thing is stock euro version. I have no idea what might be amiss.
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The fuse (everything good – did a total copper upgrade not too long ago) box menu shows various light stuff, but nothing screams 'city light' for me to check continuity from. Does anyone know which number I should try?

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I have a euro w123 280ce and my lights act just like yours. I tried to figure it out a couple times but had no luck. I'm curious to see what the issue is though.

I don't want to start splicing wires. You would think if they bothered to wire it up and add the bulb there would be some way to turn it on :D

Maybe when the wipers are on if the headlights are not or something...

one thought is that like the Euro parking lights, the key must be off for it to work. Then the P light switch will turn it on but not with the key in. I beleive its a true parking light meant to be on overnight when parked on the street to prevent collision, on my car with the L or Right selector to choose which side you want to illuminate..Just a thought.
Mine is an E320, 95..

Something else for me to try. :)

I have an English language manual for this and they speak of a thing called "headlight flashers" but don't say much about it ...

I still can't figure out how to light these bulbs up!

Operation restricted to Puff.

The wiring on a US or NAM vehicle is different than those in ROW (rest of world). The park lights are also the same in the turn signals (21W & 5W filaments). In the ROW, the wiring for the 5W is moved to provide power for the city light. This is why the bulb is present but does not turn on.

Look up US to Euro wiring diagrams, the archives are full of these (many threads on it) and wire yours accordingly.

This is how they should light up when working properly (image found on Google), but notice that the standard side markers are also illuminated. In here the owner probably tapped into the corner light of the US vehicle, to light up the city lights inside the main beam reflectors. You can do this also.

https://lh3.googleusercontent.com/eX...=w1112-h741-no

Thank you MBeige, but the thing is, they are already wired into the harness. There should be some way to just plug them in. I'll have to investigate under the fuses to see if these things are dead headed in there.