Well, since you asked so nicely. Leave the battery connected, put your left foot in a puddle and poke around with a hot switch:

Disclaimer: this is from the FSM, use at your own risk. Disconnect the battery since the switch is hot and the screws aren’t really protected. No guarantee of correct info or wiring colors. Blame the PO if you blow something up, not me.
The connections INSIDE the fusebox vary, so your car may be different. E.g. there are Portuguese, Japanese, French, Aussie, etc variants.
Info from the diagram for an ’81 300D
To remove the switch – Pull – HARD – straight out to remove the cover. (For the unitiated, there are two detents: front fogs, then rear fog position – rear fog not installed in US models)
Unscrew the nut.
The cover may/may not pop off. There are alignment pins for the switch
Remove the knee bolster/cover. The switch should be pushed forward then down.
If you can read the symbols:
30 – fat red wire, ALWAYS hot to battery (and starter switch x 2 and fuse #2)
K30 – grey/red, license plate “input”; FROM fuse 1; MAY be hot at anytime depending on switches
P30 - Green/white, standing light input; FROM starter switch, HOT in OFF/ACC
31 – Brown, ground for rear fog (not used in USA, Speculation: I think this is only for the bulb in the switch)
56 - White/yellow, driving lamp (aka headlights); TO the stalk switch pin 1
57 – (commonly grey, various foreign setups)
58L - Grey/white, parking- tail lamp left; TO fuses 3 and 5
58R – Grey, parking- tail lamp right; TO fuse 1
NSE - Grey/yellow/green, rear fog and fog input; FROM fuse 11 (or maybe 5)
NS - Grey/green/white, rear fog output
N - Grey/green, front fog output; TO pin 1 on the headlight connector(s)
K - Grey/green/purple + grey/purple, instrument lights; TO shifter, license, radio (?), buzzer (?), rheostat
The flasher (on the stalk) also gets into the mix. Pins 1, 2, 3 and 11



On the headlight connector pin 4 is high beam (white or white/blk), pin 3 is low beam (yellow or yellow/black)