High beam won't switch off!

[chrisl]

I have this really weird problem with the lights on my 93 E320

Driving back home today, just as I pulled up outside my house I noticed main beam was on and no amount of wiggling the stalk would switch them off. Since I needed to go out later I thought a quick and easy way to fix it would be to pull the fuses for main beam and then look at it when it’s light. All the other lights were working fine.
So out come the fuses for left and right main beam, switch on the ignition and still high beam but only on the drivers side!. The high beam indicator light was on as well.

I also found the fuse for the ‘optical horn’ and took that out as well but no difference!

I'm confused now, why would the lights stay on even after I've taken out the fuses. I suspect a short somewhere in the wiring, but any pointers would be most gratefully received.

 

[chrisl]

An update for anybody who's interested...

After much reading of the Haynes book of lies which is somewhat vague on the matter of all things electrical. I have a feeling that the problem may lie in the lighting control module. I’ve given it a stern talking to with the blunt end of a screwdriver and that seems to have fixed it for the moment. If it happens again I think a trip down to my local Mercedes emporium may be in order.

 

[richard]

An update for anybody who's interested...

After much reading of the Haynes book of lies which is somewhat vague on the matter of all things electrical. I have a feeling that the problem may lie in the lighting control module. I’ve given it a stern talking to with the blunt end of a screwdriver and that seems to have fixed it for the moment. If it happens again I think a trip down to my local Mercedes emporium may be in order.

I think you need to check if you got the correct fuses. I only say this because it sounds like a sticky relay .. and hitting that a few times would probably unstick it for a while. (although strange it actually turns off ever - although that could be whatever tells the relay to be on failing)

I would imagine that the 2 fuses you pulled are next to each other, and possibly you read the numbering on the wrong side of the fuse (so you pulled (lets say) 15 and 16 instead of 14 and 15

If the lights stay on after the correct fuses are removed, then there is something very very amiss - since even a stuck relay/switch/broken-electronics should not result in lights on unless there was a nasty short circuit (i.e power being drawn from wrong circuit) which could be disasterous (i.e. fire !)

Sorry if i'm completely wrong, and teaching you to suck eggs - but its worth some investigation because of the potential short circuit and nasty results !

R