Yes, hot on horn. Grounding the hot horn wire triggers the horn relay.
Yehaw! Good news on the starting circuit. It was a bad neutral safety switch. I had power to the switch when the key was turned to "start", disconnected the switch, jumpered the 2 purples and got the test lamp to light at the starter. Tested for continuity on the switch. Got nada. Pulled it off, the front contact for the purple wires is mangled and bent backwards. I may be able to fix it, if not a new one may be in order. This one was a brand new switch from Rick's Camaros.
Dinner's coming so I need to check on the turn signal flasher later. Dummy me thought that there was only one, so I bet you it's not there.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI