Some later models do have a ground wire that goes there. I forget where I had one, 87 Grand Fury maybe. So the reproduction switch is built "one size fits all".
Any could/should add a ground wire there.
Factory relied on a daisy chain of metal to metal contacts for a ground path most everywhere. For the instrument panel, it's a handful of small screws. So adding a ground wire directly from inst' housing to chassis is optimal method. You would consider male/female connector in this added wire for service purposes ( less you'll tool remove it like the amp gauge wires ). So where the headlight switch is mounted in the metal inst' housing, adding a wire with female spade terminal to this switch body is simpler, how the factory did it in later models, and better than none.I guess you are recommending one? I don't think an extra ground would hurt. Thanks
Oops, grabbed the wrong switch! Sorry.Not sure how the wiper switch ^ got into this but... yes the wiper switch must be chassis grounded to the dash also. I've found that some wouldn't run unless the switch is grounded and others wouldn't stop/park unless the switch is grounded.