74 and newer harnesses suck. I fixed this 74 dart picture below to get the Barracuda. Same issue and several wanna be engineers couldn't fix it . It had me stumped for a little while, The bulkhead connectors were corroded where the wires go into the spades.. You had to pull them out of the white plastic one by one to see it.
View attachment 1715936719
View attachment 1715936720