I had to get a new alternator today. I thought it would be a simple deal... well I was wrong. I took the truck up there and had him check it and sure enough it showed bad, so I take it home and take it off and go change it out, well put the new one on and took the truck back again and it showed low voltage. I went back home and replaced all the wiring. I checked a couple of sites first, and found this one.
I still am not sure if it's right though, at idle I have 14 volts, and when I turn the head lites on it drops to 13.8. I have never had problems before now, and I have had the old alternator since 1991. Should I have more volts than that at idle?



http://www.classictruckshop.com/one_wire.asp

13.8 is plenty at idle, my boss fixes starters,alts,usualy test with everthing on.