Greetings, on my 1987 300sdl, the left low beam is going out intermittently. And that is literally the only light not working, and again it works about half the time. I have high beams on both sides, low beam right side, etc. I changed the pigtail plug and that did not help, and switched bulbs and that did not help. I’ve replaced the fuse for that light and no help. Is the main switch the likely culprit, or the high beam, turn signal switch? Thanks!!

check fuses,and see if there's a relay.Mine had aluminum fuses,which i replaced with copper.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

Put an ohmmeter on the low beam lead inside the light and the corresponding pin that the socket plugs onto and move the wire around to see if it opens intermittently.

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Watch him go!!! link

#dontdealwithkahlil

If I wanted an easy short term fix, could I splice into the positive wire on the running light? If I was willing to temporarily be without high beam on that side?

I'd place money on the stupid "bulb warning module" being your culprit. They're famous for crappy solder connections opening up and causing misery and intermittent lights. The headlights on the Gen II 126's go from the fuse to the combo switch through the warning module to the bulb. It's possible that the combo switch is bad, but 99% more likely to be that damn warning module. Pry it open and look for broken solder joints, you'll probably find more than one. Re-solder and you're back in business.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Thanks for all the insight!!

Where is that module ( I mean I understand where it is in relation to the switches and so forth but physically where is it on the car? ). Thanks again!

It's the biggest "relay" box in the fusebox. Looks like a VHS tape shoved in there.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Thanks for the colorful image! Should be hard to miss!

Check the connector/plug at the bulb, they burn/melt.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Replace the bulb. They are cheap. Or just swap them side to side as a test.