Ok, this is what i would do. Looks to me that the alternator that you have may be a 12 SI type. I ran that number (17294) and it comes up for a powermaster 12SI. I think the 190505 may be the date code. I think the externally regulated alternators have prongs that run opposite of the prongs on your alternator. If it is then that is an internally regulated alternator and your wiring is incorrect.
Here is a tech thread on how to wire correctly for an internally regulated alternator.
https://www.chevelles.com/techref/ftecref14.html
This is your instructions for the alternator you have.
https://static.speedwaymotors.com/pdf/7294_instructions.pdf
It needs to be wired as below.
All the above info is correct.
You have a 100 amp 12si Powermaster alternator. The 12si alt is a good upgrade to the stock alt. With the PW alt, you have a few choices of how to wire the system. One wire is basic and good for farm tractors without a bunch of accessories. The 3 wire system is usually the best system to use with the stock wiring harness. If you pull a lot of accessory power off the battery, then a 3 wire system that senses directly from the battery is a better way to go in some applications.
The PM 12si will function either with only one wire connected or with the stock wiring circuit upgraded as in the Oldcutlass's link. As a one wire alt, it will read and adjust the output off the charge terminal on the back of the alt. The alt will be turned on and off by an internal circuit in the alt. Not all 12si alts have this circuit, so if you don't get a charge, you need to hook up as per the link. Term 1` will supply and control the on/off circuit. Without the 1 and 2 terms connected you lose function of the alt warning light in the dash. So you lose the heads up given when your charge system fails, or when the water pump belt fails. Another issue that sometimes arises is that the internal circuit will require a bump in the throttle to 1400 rpm to turn on the alt to begin charging. Once on, it will stay on until the alt stops spinning.
One negative of the one wire system on a stock wiring harness is that it does not compensate for voltage drop where it will do the most good. This can lead to lower running voltages to ignition and headlight circuits. The stock retrofitted 3 wire system is a better way to go as it senses the voltage at a point away from the battery and compensates for common voltage drop in the system. The sense wire reads from the 4 way splice near the horn relay instead of sat the alt or battery.
(Do Not disconnect the battery while the engine is running!) Doing this will damage the alt/regulator.
If that's confusing, please read the following links and they should get you up to speed. This will help you determine the best system for your application. Even though the link is listed as "catalog"' each link covers a different aspect. At the very least just read through them and you'll gain the knowledge to best suit your needs.
Did you ever buy that volt/ohm meter? You'll need one and it will make your job much easier instead of just guessing what's going on. Plus the results will help us help you should you need the help. Without it, we're all just giving our best guess.
https://www.powermastermotorsports.com/faq-alternators_a.html#1 How do I hook up a one wire alternator? When to use a one wire alternator?
Catalog CHEVY MAIN ELECTRICAL POWER-UP SYSTEM
Catalog For most applications, the advantages of a THREE-WIRE alternator will far outweigh the little time saved with a ONE-WIRE installation
Catalog REMOTE VOLTAGE-SENSING IS THE KEY TO GOOD ELECTRICAL SYSTEM PERFORMANCE…
Catalog ALTERNATOR WIRING KIT for the GM DELCO“SI” series alternators
Your battery voltage without the engine running should be about `12.6 volts. With the engine running you should see about 13.8 volts. If you don't see a rise in voltage after the engine has been running for a few minutes, blip the throttle up to 1400 rpm. If you still don't see the 13.8, then your alt is not charging. you have electrical issues or the alt/regulator is caput. If you see over 14.5 volts, you regulator is bad and you are over charging. This will lead to a cooked and damaged basttery in short time.