65 Dart GT Turn Signal and Bake Light Issues

I would do some testing before you order. You can get aftermarket wiring diagrams at MyMopar and some shop manuals same place, FACTORY shop manuals, and they are free. I believe there is a 65 over there. You may have to accept Dodge/ vs Plymouth or vice versa

The brake light switch should have power to it at all times. When pedal is depressed, brake power goes to the TS switch.

The inputs and outputs of the switch are as follows:

(You may or may not have an external hazard switch)

IN: Switched brake light power with pedal depressed

Turn signal flasher power when key is "on"

OUT:

Left rear turn/ brake
Right rear turn/ brake
Left front turn
Right front turn

The fronts branch off (sometimes right at the TS switch connector) and feed the dash indicators

If you have hazard switch, it is 4 terminals, which are all 4 connected as one when engaged. It is fed a separate flasher, powered at all times. The remaining three branch into the switched brake power (which feeds both brake lamps with TS switch centered) and one to left front and last to right front.