86 300E low beam headlight problem.
 

1986 300e passenger side low beam headlight problem

Ok...I have thouroughly searched the site and gotten valuable information, followed it and am still stumped.

1) My passenger side headlight went out right before I was going to get it inspected.

2) Bought a new bulb(in retrospect this was a foolish thing to do before I did other steps). Replaced bulb . Did not work.

3) Driver side bulb for low beam headlight was working so I switched it to passenger side. Passenger side headlight still did not work.

4) Looked up mercedesshop for fuse list (since my car seemed to have lost its fuse list). Thanks to those who have posted the list electronically. Replaced fuse 14. (replaced 13 - 16 as well for the heck of it). Still did not work. Note the High beam on the passenger side is working so I cant see it being a wiring issue. Am I wrong..?

5) after much searching on Mercedesshop for further info I replaced fuses 3,4,5 as well just in case and also 'screwed/turned' the fuses in place in case the leads were corroded. Still nothing.


Can you guys help? Do I have to check the relays? Should I get a whole new set of fuses and replace the lot(thats seems to be a ineffective 'carpet bomb' approach)? Can it be the wiring(even with the high beam working)?

Appreciate any input.

Turn on headlights and test yellow wire in bulb socket for power the Yellow is low- White is high- Grey is fog- Brown is ground.
Unfortunately it could be anywhere (exterior bulb failure monitoring unit, combination switch, exterior lamp switch, and all points in between).
A little fuse mania is cheap and can not do much harm though.
Good luck

Let me revise that a little, its probably more like: (fuses, exterior bulb failure monitoring unit,headlight, and all points in between)

pull the electric connector from the nonworking bulb.
chances are the socket assy has burnt up. a replacement
can be had at your local parts store.

I just changed my socket on the drivers headlight a few weeks ago. It had the same problem as you discribed. Look at the end of the plug, mine was discolored and looked like it had seen some heat.

I picked up a plug at autozone i think it was 6 or 7 bucks.

You should solder the wires and use shrink tubing to seal the conections. That way you won't have future corrosion problems.

I third the melted connector. Very common problem. The ones they sell at Autozone are actually much beefier than the wimpy OE connectors.

You do not need to use high wattage bulbs to get a connector meltdown, but that would make it worse.

Checked connector and my idiocy.
 

Okay I checked the connector (the white hard plastic 'connector' that you plug the bulb into and that has three wires going into it. ). It seems ok i.e not burnt or anything. In order to do a comparison I compared it to the other driver side connector and they both look pretty much the same. I dont mind replacing it just in case but does that mean I would buy the connector and have to strip the wire and refit the wires into the new connector. (just trying to figure how much is involved work and time wise). Is this my only option left? I am also getting a multimeter today to check the fuses and connections as well.

Also I have read posts here about how not to do any work in a rush or when your annoyed...well I did ....and I regret it....because I was in a rush I didnt plug the drivers side headlight(the one that was nice and working and I was using to compare) in properly enough into its housing....and the next time I checked it the bulb had popped out and MELTED my plastic housing that holds it in place...now I have to get the whole DA** housing thing replaced..... :eek: I guess I learnt my IDIOT lesson the hard way....no more shortcuts...ever again. :mad:

Probably the bulb out warning relay, I ran an extra wire from the fuse to the lamp to cure mine as I'm not quite ready to pop for the relay (about $200, I think). Might also be an open wire, I've not manage to check it all, I don't want to split the harness at the moment.

Right low beam, eh? Same as mine, wire looks fine, has no voltage, was intermmitant for a while, then dead.

Peter

On a side note anyone know what would cause fog lights to work with high beam on but not with low beam? Same relay? Or has this ever happened to you before?

I had the same low beam problem on my 87 300e. I sprayed 3M electrical contact cleaner (bought at compusa) on the prongs in the connector, let it sit a bit, plugged it back in, & voila, the low beam worked & has been fine ever since.

Christine- SHES ALIVE!!
 

Anyway I posted this many moons ago....never got the headlight to work....drove around like a hare brained idiot with his brights on for a while...anyway I was out on vacation for the last two months(cushy job..:) ) ..and when I got back I got the tires changed on the car and lo and behold the headlight is working fine!!!! :eek: .. I had tried the whole deal with replacing fuses and contact cleaner and bulb replacement ..nothing worked... even bought a voltmeter and checked that the voltage was about half of what the other side was putting out... then i took the two months off...but before I got a chance to try anything again...Christine fixed itself....GO FIGURE....either I have reallly slow acting Contact cleaner (2 months????) ..or mein auto ist alive....!!

Probably a bad lamp out warning relay ($200 or so) or a loose/broken wire in the fuse box. Occasionally, the screw that holds the wires to the bottom of the fuse holder or relay plug will come loose -- the result is restricted current or low voltage to the lamp.

I simply replaced the wire from the fuse to the headlamp. I still have a lamp out warning bulb lit, but I have both low beams.

Peter