Went to start the Bronco and the starter wouldn't stop starting and the ground from the alternator to the voltage regulator melted.

I checked the starter relay by disconnecting the starter and measuring voltage across when key goes from on to start. Seems to work.

Ignition seems ok I get 12ish volts to the starter relay when key on, and 12 volts to starter when the key is on start but that's when the ground wire starts getting hot.

All my trouble shooting was without the starter connected so I don't think that's the problem because ground wire continues to get hot.

Could the alternator be bad, could the fused wire that comes from the harness to the starter relay be shorted somewhere???

Any way I'm stumped and would appreciate any help.

Check to see what color wires you have to the "s" and "i" terminals of the solenoid. "S" should only have a red-blue wire. "I" should be brown.

Fried regulator ground wire is an indication of a poor ground cable or connections. Check those out.

Thanks for the response. The "s" and "i" appear to be connected correctly so I'll keep looking for ground issues.

I've had a starter internally go out and wouldn't turn off?