Stupid lights!!!

[WRMZ71]

STupid.....LighTS!!!
Does anybody know if there is a main ground for the turn signals and dash lights inside the cab on a 71 chevy halft ton? when i turn on my left turn signals they work fine, when i turn on my 4 ways they work fine, but when i turn on the right side both lights in back blink the front left side marker light blinks and all the dash lights blink I've replaced the turn signal switch, the light switch and pulled off the rear wiring harness and there aren't any faults. I've figured out that the rear left turn signal is blinking through the brown wire which is lights???? Any ideas ???? HELP!!! oh yea and you've seen this post in the parts board thats my bust, I'm a newbie