1979 Pontiac Firebird tailight problem

Electrical problem
1979 Pontiac Firebird V8 Two Wheel Drive Automatic

I have an old chev cpe with 79 firebird column and painless wireing. Problem is when lights are turned on. With lights off everthing works good, but when you turn on lights r turn blinker causes also third light to come on not blink, and when L turn causes left tail light to go out and blinker works