1st time using the site. Need help trouble shooting electrical problem on my 59 Ford F-100. Generator light has been staying on, went ahead and replaced the altenator with a new one. I have the same problem and my dash lights and head lights are dim or go out now. thanks for the help.
Welcome to FTE!
Is this a truck you have done much work on electrically? There isn't a ton of wires in the harness but they all need to be intact as well as any connections. There are several ground staps. You haven't said what engine you have. Original '59 or what? Could be as simple as a loose belt, not to insult you or anything. I personally can be the Prince of Stupidity! Shop manual is always your best bet as The Fridge Buzzard has said. Get it and then you will be able to ask more specific questions.
Has it been converted to an alternator? Look up full field testing. In a nutshell that's where you bypass the regulator and read the volts at the battery while it's running. 15 or so volts, gen/alt. Nothin', volt reg.
GM one wire is the ooooonly way to fly IMO