82 240 D zero voltage to cabin...
 

WTF?

I have not personally verified the readings, but battery fully charged, voltage at alternator terminals. NOTHING in cabin. no start, no radio, no headlights, no cabin light... nothing.

anybody?

It was a long time ago so I don't remember the Details. In side of the Fuse Box a Wire became un-soldered to one of the Buss Bars.

To My best recolection it was a Green Wire.

In any event probing with you Meter or a Test Light will tell you if you are getting battery Voltage up there.

Main power relay not activating with keyswitch if it has one? Power feeder to the fuse panel bad? Had one mercedes where the power was divided at the terminal connection and that feeder connection had gone open. Not sure if it was a gas or diesel mercedes car though.

According to my 1983 240D diagram, should be the same for yours...

There are 5 wires on the big nut on the starter
- battery + (25 mm2 or #4 American)
- 2 reds from the alternator output (2.5 mm2 or #14)
- 1 red to glow plug relay (4 mm2 or #12)
- 1 red to light switch pin 30 (6 mm2 or #10)

If you have absolutely nada on body power I would check that last wire. Everything goes through that.
From pin 30 on the light switch it goes on to F2 on the fuse block, which is practically everything on a 240D body that is unswitched.

Also from light switch 30 are 2 reds that go to key switch 30 which feeds most of the rest of the switched loads via key switch contacts.

cool, thanks Jay, I figured I needed to start there.

I was pulling that bundle of wires off that connects to the starter on my 1981 and a bunch of them the insulation was rotten. I'd check that. Maybee a short?

May not apply, but also check the ground connection at the negative terminal to the body, and the ground strap from the body to the trans bell bolt.