toggle switch & green light?
 

I have an '81 300 sd that has a toggle switch and a green light that goes on when I flip the switch. It is located below the ash tray. I have no idea what this does. I'm sure it is something added on by the previous owner. Any clues?

Could be for any number of things. Usually switches found like that were for some aftermarket front or back fog / spot lamps....have a look to see if you can see if any were fitted.

Saying that though, i dont think you have to have rear fog lamps in the USA as standard do you?

Just a guess, but possibly an aftermarket alarm system?
I recently purchased an '81 300TD and I noticed a small toggle switch under the dash, just a few inches from the e-brake.
I also have a little red light on the top of my steering column...not sure they are connected but I have no idea what else it would do.

I took the dash panel off only to find that there is one heck of a mess of wires that go to nowhere...

Under the hood I have a small bull-horn looking thing mounted on my left fender with wires going thru the firewall and into the cabin. Not entirely sure that it was an alarm, maybe an external PA system? (but no evidence of a CB mount anywhere...)

Just a hunch!

toggle switch, green light
 

Thank you for the ideas. I don't have rear fog lamps. I will check under the bonnet for signs of an alarm system. I have been using the device to get rid of my front seat passenger. I pull over, flip the switch that activates the green light and tell the passenger to get out immediately. So far so good.
Larry

I just about pee'd my pants when I read that!
That is too funny!

one more thing...
 

larry,
This may be a long shot:
I used to own an '81 diesel VW Rabbit, and I just remembered that it had a instant-block-type heater with a manual switch ion the dash. It also had a light that went off when it was ready to go. (5 minutes or so)

It was hooked up directly to the battery as opposed to having to plug it in.

Maybe check to see if you have a block or other type of heater installed?

-Brian