Delco alternator question

[BKCowGod]

Posted this on the IFSJA, but I realized there's a lot of smarts here too. Any suggestions?

I searched, I read, I'm still stumped. Patient is a 1980 Cherokee 360.

Battery is an Optima Red Top that holds great charge. Sitting at 12.5v with the truck on or off. Ignition is MSD, installed three days before this happened along with new TFI coil & stuffs.

Alternator was pegging the ammeter, then I smelled burning and it dropped to 0. Turned on headlights and it dropped to negatives, so I replaced the alt under warranty. Current alt is still at zero, still dropping when lights are turned on.

Big red wire from alt gives me 12.5v at the alt with truck off, zero ohms resistance.

Smaller red wire gives me 12.5v at the alt with truck off, zero ohms resistance.

Brown wire gives me 0v.

Is my new alternator bad out of the box, or am I missing something here? Belts are good, truck runs beautifully, but I have a camping trip coming up and I really don't wanna fix this problem with my mastercard. Heeeelp!

 

[getlost4x4]

are you using a one wire regulator hook up on your alternator?

i have a 100 amp chevy one wire laying around. its never had a problem with charging. i even have an extra rebuild kit for it as well.

when the motor it was on was running it was always about 14.4 Volts on the meter. they seems to work good on mine.

i remember when i first tried using one in my toyota with the extra hook-ups i messed up the wiring and burned it up like yours is doing.

 

[ntsqd]

What happens at the brown wire with the ign on but the engine off and the wire disconnected?

 

[BKCowGod]

Discontinue diagnosis... Just for fun I pulled the alt and brought it to Kragen. The brand new (reman) alt was bad. They were kind enough to warranty replace it even though I didn't buy the alt (my shop did).

All is well, charging nicely!

Oh, and San Jose folk - Matt and Julie at the 4th St Kragen are GREAT. Only FLAPS employees I've ever respected.