82 240d

Battery and alternator checked ok. I put test light on meg battery lead to post ,light appears fairly bright in test light. I removed one fuse at a time,glow plug relay and alternator plug with no change to test light .

What else can I do?

Try unplugging the headlamp switch and test again using the same method. Also see if the ignition switch is getting warm and moving the key to see if it changes the light, IIRC the ignition switch is not easy to just unplug.

Good luck and please complete the post.

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

I will try that and report back once I track it down

Pull all the fuses until your test light goes out or dims. Then address the problem to what's on that particular fuse. If it has a power antenna, I would start there by unplugging it and see if the discharge drops.

On the 123s the battery power goes to the key switch and light switch with no fuse direct from the battery. The fuses are all on the load side of the switches.

Only fuse #2 is coming straight from the battery and feeds the dome light, power antenna, clock, stereo memory backup (and not much else on a 240D!)

If after isolating all loads you still have a drain, (with the battery disconnected) lift the alternator connection, safely isolate the end, and reconnect the battery. If this makes your drain go away you have a blown (shorted) diode in the alternator.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Unplugging red leads to light switch turns test light off. It appears to be a drain from light switch

Well that's a clue.

The lighting fuses are:
1: instrument lights, right side park/tail, license, "lights on" warning buzzer
3: left side park/tail
7: right hi beam
9: left hi beam, dash indicator
11: fog lights, right low beam
13: left low beam

I looked through the diagrams and it appears that there is no connection anywhere if the switch is in the Off position. I suspect you may have an internally shorted switch.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Yes I agree, I have noticed in the last few months that headlights would suddenly dim then return to full brightness. Also found a wire from radio to red lead on headlight switch,radio would intermittently lose power. I have ordered new switch-see what happens