Turn signals acting up

[82chevdiesel]

Ive been chasing grounds and troubleshooting all weekend and Im starting to go nuts, nothing I try works. Its an 82 c30 dually and my left turnsignals dont work. The headlight grounds are in good shape, and there is continuity to all of the taillights to the tail light ground on the left side (no ground on right but I hear its all routed to the ground on the left.) I changed the headlight and turnsignal switch to no avail. Its acting like theres a short or bad ground somewhere but I just cant find the problem. Instrument panel ground is good too and I dont have blown fuses or lights.