Once in a very great while it becomes necessary to replace the turn signal switch on a 65/66 Mustang. Once it has been determined that the switch needs to be replaced, you will discover that you have to reuse the old connectors. One is a two-wire connection that will only plug together one way. That connector is for the rear turn signals at the tail lights. If those two new wires are placed into the old connector backwards, what will happen is the right rear turn signal will start flashing when you signal a left turn. Not that big of a deal, and all that you have to do is switch those two wires around and you're all set.
The six-wire connector is sort of a different story, though. The two connectors will only plug into each other one way, but, there are all sorts of wrong ways to place the new wires into the old connector, and, if done wrong, all sorts of disasterous consequences will follow involving smoke, melting wires, etc...
Here is how those six wires are supposed to be installed in the old connector. If you look at the connector from the orientation shown in the picture, you will notice a slot in the cross piece in the center of the connector. Holding the connector so that this cross piece is pointing up and down, and with the slot closer to the top, the wires go as follows, going clock-wise beginning at the top left corner.
1)The top left corner has a yellow wire, which brings power from the headkight switch to the horns.
2)The top right corner has a white wire with a blue stripe, which goes to the front right turn signal indicator.
3)The right-side middle wire is a green/white wire which goes to the front left turn signal indicator.
4)The bottom right wire is blue/yellow, which takes power to the horns.
5)The bottom left is a blue wire, which brings power from the turn signal flasher.
6) The middle left wire is green, which brings power from the brake light switch, so that the brake
lights are flashing on the appropriate side while the turn signals are flashing.
In the wiring diagram, you will notice what appears to be some extra wires. I drew it like this, oddly enough, for the sake of clarity, so that one can clearly see what each wire is doing. Wires 1 and 8 are both white with a blue stripe. There is actually only one white wire with a blue stripe coming out of the turn signal switch, with the same thing happening with wires 2 and 7, which are green with a white stripe. There is only one green wire with a white stripe coming out of the turn signal switch. If you look at the 6-wire connector that the turn signal switch plugs into, you will see two white/blue wires coming out of the place where the one white/blue wire goes in, with the same thing happening at the place the one green/white wire goes in. Two come out. What the switch itself has is one yellow wire bringing power in for the horns, one green wire bringing power in from the brake light switch, one blue wire bringing power in from the flasher, one blue/yellow wire taking power out to the horns, one white/blue wire taking power out to the right front turn signal and right dash indicator, one green/white wire taking power out to the left front turn signal and left dash indicator, one orange/blue wire taking power to the right rear turn signal and brake light, and one green/orange wire taking power to the left rear turn signal and brake light, with the last two being that two-wire connector. There are some aftermarket turn signal switches with wires that don't really match the colors of the Ford switches. I don't know why anyone would do such a thing unless it had something to do with cheap, but, that was what they did. If you have such a switch, the last two pictures will show you the locations of the wires on a Ford switch.
