Sounds like you’ve found one of those old “easter eggs.” Back in the day a lot of Fords had hidden switches for the dash lights or the horn that were wired into the main fuse block. The trick is usually a pattern that triggers a diagnostic mode or a “fun” light show. Start by checking the fuse panel for a double‑tap or a button that’s been wired into the horn circuit, and try swapping the horn relay to see if the lights respond. If it’s a real software switch, you’ll probably have to pull the radio or dash panel to access the wiring diagram. Keep your eyes on the dash, and you’ll see if it’s just a clever prank or a genuine hidden feature.