Low beam , parking tail lights ,brake lights not working

One thing I haven't done yet is change the turn signal high, low, beam switch.

I've checked grounds replaced circuit boads , replaced all bulbs ,dash board included . Installed extra ground from battery to frame and frame to bed of truck,

i'd get schematics of your lightning system and a digital or analog multimeter to test continuity on the wires. headlights and the turnsignals should be on separate circuits. any turn signals work then??

Yes turn signals work , also back up lights work.high beams work. No parking no tail lights, no brake lights, no low beam