Long time lurker, first time poster.
I've had this issue for quite some time but been too lazy to investigate. Finally got around to it. Long story short, I believe there is a plug that has too much tension which forced a connector to be loose in the plug. To fix, I cut tape (relieve tension) and added a zip tie (secured the plug). Been testing this about a week with my tailgate panel off. Steps & pictures below.
1. Remove both rear lights on the panel. I used a plastic pry tool to pop them out. Unclip & remove. You do not need to remove the 10mm bolt behind the lights.
2. Remove the cover from the grab handle. There is a 10mm bolt behind it. Remove the bolt.
3. Use a plastic pry tool to carefully go around the panel and pop off the panel. It should just be plastic clips along the side & bottom.
4. In the center of the door you will see a metal bracket, black box, and a few plugs. Disconnect the harness that is not directly connected the black box (see attached pictures). In my case, a few of those wires were bent and slightly loose. I pressed on them with my fingers just to straighten them out.
5. The plug above is also secured to another harness using tape. Cut that tape. This should allow the harness to not have as much pressure.
6. Plug it back in. To take it a step further, I zip-tied that plug together to ensure a solid connection.
7. Put it all back together.
had the flickering issue for a little while now and experienced the full black issue the other day. i'll be trying this when i have some free time.
will report back if it solves the issue on my end. Have you confirmed this solved your issue? seems like its been a good 6 months since you did this fix.