1998 Chevy Truck tail lights

Hello.
My tail lights and reverse lights do not work at all. My brake and turn signals work when my light switch is in the off position. Nothing works on the rear end for lights when my light switch in on or in the running lights position. Everything on the front end works and has new bulbs all around.
Also whenever I turn on my light switch or hit my brakes my blinkers blink real fast. Also when I hit my brakes even when the key is out of ignition my its the same as turning my key on. The fuel pump even primes. All the regular fuses are good and i've been unable to find any bad grounds.