a1cnc

I am working on my truck I recently bought. The tail lights are driving me crazy! The other night I finally fixed my fuel pump and the truck was running great. I had all my tail lights, directionals and plate lights. I was going to take it for a quick test ride, I put it in reverse, backed up about 20 feet and stepped on the brake and noticed I had no brake lights on the bed but the cab brake light came on. So I got out and noticed ALL the tail lights were out. If I turned on the directional they would blink dimly and real fast and the plate light was blinking too. If I turned on the hazzards the tail lights would blink full brightness.
Next day I cleaned the ground that I could find and the lights were back on. So again I was going to take it for a ride. I closed the door to go and sure enough the lights went out. I didn't even slam the door. I have jiggled every wire and connector I can find to no avail.
Any one have any ideas where to start?

TIA

a1cnc

Just as a follow up. I finally found out the harness is screwed somewhere between where it plugs in in the engine compartment and the rear where it plugs into the harness for the taillights. I used the heavy gauge wires that are run from the factory for trailer lights and bypassed the original harness. I just cut the plugs off each end of the original harness, Spliced them onto the trailer wiring. Then plugged it back together and all my lights work again!