68 Camaro RS. The rear light harness was really flakey so I replaced it due to too many splices and wires going no where. My tail lights and turn signals work, but the brake light and the back-up light works on only one side. I have the four light set-up. When the brakes are pressed, should all four lights come on? Also, for the turn signals, do the inner, or the outer lights come on?

I think all four are suppose to work on the brake lights and both on one side for the signal.

yep, all four w/ the brakes on, and both on one side or the other for turn signal