Okay, I know this is an ongoing topic and it seems to be having all kinds of responses. Before I go to an actually audio/electrical expert and spend numerous amounts of money. I want to state my scenario and see if it has been seen before.
I hard installed a Nilight TR-04 60" Triple Row light bar by splicing each wire to their corresponding wires on the tail light themselves. So once wired up and tested, everything worked fine for about a week. Then I started to notice the left blinker inside the truck would start blinking fast, normally a sign of a signal malfunction. Parked the truck and tested them, everything worked the way it should, restarted the truck and drove about two miles, blinker started again. So this time left the truck running and sure enough, left tail light was not working neither was the left leds on the light bar. Shut off the truck and restarted, everything worked fine. Fast forward a day or so, no indications of any tail malfunctions while driving and just today, I'm driving home from work and a guy pulls up next to me and tells me I have no brake lights at all. Pulled into a store with windows and noticed he was right, not brake lights, but the turn signals worked fine on both lightbar and truck. Shut off the truck and waited a bit, restarted and everything worked again. Don't know where to start the trouble shooting, Any ideas?

 

I strongly urge you to pull the truck into your garage, get out some tools, remove that giant POS tailgate bar, throw it away, and enjoy your truck.

I know of no one who has had one of those things that has NOT had a problem with it sooner rather that later.

 

I don't have a tailgate bar, how infamous can it be!?

Tell the people what you drive, it might be a clue to one of the other hundred members who apparently suffered from this.
Meaning your 2010 XL truck might be different than a 2020 Platinum.

 

My apologies, 2015 F150 King Ranch with the BLIS system.