1967. Since nobody else answered, I will try and makes some guesses based on the wiring diagram and memory. Your photo does not show at work.
Brown might actually be black/orange which is the blower motor. Blue is the oil pressure switch on the engine.
I'm thinking your black wire might be the one running down to the tranny to activate the kickdown solenoid? The factory did not show that wire on the wiring diagram. It's shown on the '68 diagram.
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
