Left side tail light signals/brakes not working

OK so the entire left light is out correct? Running? Turn? And Stop? Right one is good and fronts work but left flashes fast? Plug in the trailer and left turn and stop don't work? Is this truck equipped with the factory tow option and the rear light socket. Asking because the description sounds like the body control module may have failed. It powers the lights directly and if it has the tow package with the relays and the lamp was the problem the trailer lights would still work because they are connected to the light feeds before the rear lights. See this a lot if the vehicle didn't come with a full tow package but someone installed a trailer hitch and wired into the rear light harness. The BCM is behind the trim panel in the right side footwell in front of the door. This is not a plug and play part though, you need a scan tool that can retrieve the as built information from the current BCM, then you swap them and use the scan tool again to upload that info into the replacement module. Once that is done then you can code the BCM into the engine control module to turn off the antitheft system so the truck will run. You also will need to retrain all of the TPMS sensors.