Have an 1980 f100, I put an 1980 light switch in it. The serial number on cluster is 1981-86. Signal lights blink properly, but only the brake light blinks on cluster. There is a large gray/ yellow stripe wire going into a fuse link? Then into the fuse box . Out of that fuse link, there is a small black wire hanging. Can't find were it goes, but it is hot with switch on.
