As Bill suggests. This is an Echlin part, Chart says one of these is good for 4 amps, put two in parallel for up to 8A. Cheap, easy. The reason it won't perform in Hi:
You need two of these in parallel!!!! If your draw is 6A.
Buy here or Napa VT6187 You don't want a live PC board under dash, full of soldered components, mounted to what? How do you wire to it? Forget that thing. This part Bill mentioned is for trucks baby, stud mounted and tough screw terminals. Yeah!
FYI: Those switches are always Hot. That's why they have ceramic bodies and are mounted away from other components. As you can see, the reducer is also ceramic. When you see ceramic, think it's going to get hot. Other switches are not insulated that way. Don't fret over it.
