Shoutout to the guy who told me to check the grounding strap before chasing electrical gremlins
Got a 2018 F-150 in the shop last Tuesday that had this intermittent issue with the taillights flickering. Spent like 2 hours swapping relays, checking fuses, tracing wires. Finally called a buddy who works at a dealer and he just says "did you check the ground strap at the frame?". Sure enough, it was corroded half to hell. Cleaned it up, problem gone. Felt like an idiot but learned something. Has anyone else had a simple ground fix save them a ton of time?