My 93 400E getting there need some help.

Oh no all I did was look at the lamps with the cover out now my passenger taillights wont come on! Check the fuse its good,replaced it anyway! Changed bulbs no light. Is there a relay or something? Both lights no power. HELP!

Can a headlight relay going bad cause this? Can you test a relay?

Running light... which light are you referring to? Not the headlight... the turn signal light?

I was referring to the taillight when the headlights are on, it just quit working on the passenger side no power at all. Can it be a relay. Everything else works as its supposed to.

Ok here is the update so far, replaced the headlight relay and now all the lights work but the dash light saying I have bulbs that are out is still on. Now what do I check? Thanks again all.

Aieee. You really shouldn't have to cut stuff. Check the voltage coming out of the fuse box for that circuit. And if the fuses are old change them all and clean the contacts.

No. There's no relay for those lihgts. Yes you can test a relay.

Got a volt meter? If not, get one.

Ok found the relay and replaced it now all light work but the the light that says a light is burnt out is lit up. The lights are burnt out in the climate control unit could that be it? It wasnt on before but the relay was going out so maybe it couldnt tell. Is there a seperate relay for the burnt out light sensor or is it in the headlight/taillight relay? thanks all.

Now, you need to make sure all the lights are working... also some cheap bulb has the wrong resistance... which would cause that light. Pop out each taillight bulb holder and make sure all bulbs are lit.

In addition, many forget to check the rear licence plate bulbs (modern models at least monitor those too)...

There IS a relay? Oh.

Some of the Asian and mexican bulbs don't work right. Get a German one. Cheap at the dealer. The resistance is utterly critical in these bulbs for the whole system to play right.

Ok so cheap bulbs will do it, how about the bulbs that are not lit in my climate control unit? I did check all the lights and they are on and work well, but what kind of resistence am I looking for? How much is the system checking for? The relay I got is not new (after paying

600 dollars for the engine wiring harness 200 for that was not in my range yet) so is the sensor for the light bulbs exterior of that relay or is it part of it? Thanks again all.

Dunno frankly. All I know is if you use German bulbs it's supposed to work correcly. If it doesn't then this isn't the problem. The bulbs aren't that expensive at the dealer and it's worth a shot.

I will do that, bulbs are not the issue tho, I am thinking its still the headlight control relay (its used but not destroyed inside like the former, metal tabs inside burnt up) My only question is does that relay control the bulb light in the dash, I am sure if it does than its the culprit if not whereever it is thats the culprit. Thanks all.

Impossible to say without a schematic. You're really gonna have to look at one I think.

Ok here it is, I have looked at the schematics and I will tell you that It is like nothing I have seen before. It shows relay locations (which it doesnt seem to show all) and has lines that dissapear to a number that I can not match up to any of the other diagrams or relay pages. That is why I am asking around. Not very clear. I was just hoping someone has had a headlight control relay issue, that they had to have replaced and can inform me. Thanks all.

Ah yeah, welcome to Mercedes electrical systems. Difficult to believe as it may be the schematic is not wrong. Just unbeleivably difficult to follow.

In the bad old days the entire schematic for the 108 chassis car fit on one (albeit fold out) page. The scamatic for my 300 SD is a manual thick than the chassis manual.

Make sure you have the right year and model, and keep looking it's in there someplace.

Well it looks like its the headlight relay, There is no bulb monitor in the schematic at all. The number on my relay is 1265420132. If anyone has one of any kind around would love to get it. Thanks for all the help. 125-200 is pricey for this thing new. Hopefully I dont have a short.