Weird Lighting Phenomenon

[502ms]

I have noticed that when I have my headlights or parking lights on, my rear lights do not have indication of stopping or turning (signal). When no lights are on (parking or headlights), they work fine. This was the case before I rewired the entire truck with the painless harness for 67-72 trucks, and has not changed even with the LED tails. Is there an assembly that needs to be adjusted under the dash? Just curious.

Everything else works the way they should.
1972 Chevy C10.

Thanks in advance.

[cdowns]

bad ground

[W.I.P.72]

Yeah ground is the only thing i can think of if you just replaced all the wires.

[502ms]

Any ideas of what else can be grounded? My engine has new battery cables, ground cables and I did not see anything in the cab that needs grounding...
Posted via Mobile Device

[bk2life]

not exactly sure just makin a guess here, new updated wiring/fuse block, maybe try a new flasher.
not sure if that will do anything but making a guess.
dont think it is a ground be cause they work.
worng plug/wire placement in column/turn signal switch?

[cdowns]

EACH AND EVERY LIGHT BULB NEEDS A GROUND and everything else for that matter in order for voltage to flow properly

[fixit-p]

It is a bad ground as already stated, most likely at the light buckets or bed to frame. With the headlights off the Brake/Turn lights have alternate ground paths available but once the lights are on it removes the alternate ground path. Best way to test the condition of the ground at a given circuit is to do a voltage drop test on the ground side of the circuit anything over .2 volts indicates a bad ground.