'99 replace alternator now no start

[gahellinger]

My truck started overcharging, measuring 15-17 volts. I drove the 2 miles home and parked it. Assuming a bad regulator, I replaced the alternator. I now have minimal juice, enough to work the door locks and the warning buzzer but nothing else. No gauge electrics or other signs of life. I have reset the negative battery cables without success. I also checked the fuse in the interior and engine fuse block. Is there a fuse or relay I should check that I have missed? Ideas?