1978 Mercedes 280 SE Light Problem

[gol-d-lox]

I have been trying, to figure out what the problem is with my lights. Please help. I purchased this vehicle in lein sale, 1st mistake. After I thought all problems were fixed, and all lights and bad bulbs replaced, turn signals work, emergency flashers work, and headlights work. But when I turn the headlights on, now the turn signals and flashers don't work. I've ck'd all fuses, and a acquaintance, changed the light switch and turn signal switch. I can only guess either those switches from Pick-N-Pull were bad also or, he wired the light switch incorrectly. Since there are many wires going to this switch it is very possible. I need a diagram for the wiring of the headlight switch and any other possible reasons for the problem I'm having. Pleeeeeeease.