Is this a good quality voltmeter or a Harbor Freight inaccurate POS? Quick and dirty way to make sure your voltmeter is in the ballpark: If a 12v battery has sat overnight with no load or charging you should get around 12.6 volts.
If you are measuring the voltage at the battery terminals: That's (15V or more) high voltage for a GM alternator esp. for YOUR warm location. I would check to see what the alternator is seeing on the "sense" wire. Start engine and check the battery output lug and write down. Check both of the alt connector plug wires voltage and write down. Check battery voltage at battery terminals and write down.
With the above we are looking for a high resistance connection causing a voltage drop. Likely from alternator to main bus where the "remote voltage sense" wire is tied and goes back to the alternator's regulator plug. The 2 wire connector plugs into the internal alternator regulator.
That or this alternator is stuck full field (defective) and will boil the battery dry and very short lamp life.
Yep, it's a HF High End POS. It hasn't failed me yet. I carry my Gold Plated Fluke and a load tester in the pickup for service calls.
The new alternator seems to have a 13 v+- output.
I'm almost there. So far:
Fabricated a complete floor in the cab.
Rebuilt the seat.
Rebuilt the hydraulic controls.
Replaced and rewired all the lights.
Replaced the battery.
Repaired the starter.
Patched a hole in the gas tank.
Removed the primary fuel filter and added an inline filter.
Replaced the hydro booster.
It's probably road worthy at this point
I've still got a few small leaks here and there. One is the PS pump seal and one is in the PT.
I'll be doing a lot of metal work and painting on the body but for now it should hold.
Air vents are full of whatever the rats and squirrels left behind. The smell kills me.
I'll have to go over the motor and the hoses.
The driver window needs a new mount
I still think it was a good deal for 2000.
But for now, it's time to make money.