I think I've got this thing figured out, but as I didn't test the board before any modifications I never got reference values.

What I need is somebody to measure the resistance from any one of the contact pads to the common signal wire on the back.

I'd like to know I've got this right before taking my dash apart again to test the frankenmetra board.

Just check resistance between any one of the pads marked with a red arrow on the front to the 4th prong on the back, also marked with a red arrow: