Could be the case... I removed the horn relay and reconnected the battery. The headlights started flashing. When I started the truck, it started fine and the headlights quit flashing. Incidentally, the door lock started its click, click, click thing again, even though I used the key and not the fob. Suppose they are related? In the meantime, I'm adding one of those cheap Harbor Freight battery maintainers I had lying around. I'll monitor it a bit I guess. Maybe it's just time for a new battery. I obviously keep my vehicles way too long.