47 business coupe

I bought a 47 plymouth p15 upgraded to 12 v and a new wiring harness and all the lighting of gages don't work but the running or driving lights do (light stitch is on and knob pulled out) I found a ground that seems to be loose coming off the back plate of the gage housing And no where to connect stripped end. Do I just crimp on length and connect to frame? Or to the battery? What's the best way to ground said wire?