Wiring a 55 chevy belair trying to get the turn signals and brake lights working. However only one light will come on at a time. I get one to work and then the others won't. Not sure what is going on.

First off make sure all your grounds are good before starting the project. Is the wiring coming from the coloum good as far as your turn signal switchs? From there check wiring at your blinker control (the little relay that causes the bulbs to blink). From there - out should run directly to the lights in the rear of the unit.