Alternator won't charge for 1999 Chevy Camaro with 3.8 L engine: No engine codes

Question:

My battery was going dead on me and when I checked my battery voltage at idle, it was discharging. After cleaning all the grounds and having the same result, I replaced the alternator with a rebuilt one from a local parts store. However, my battery light is still on and when I checked it, it was still discharging. I thought the rebuilt alternator was defective so I returned it and got a 2nd one installed but I got the same result. What have I done wrong?

ATS Advisor:

Some aftermarket alternator available has a regulator with 12 volts triggering signal to make it work. If you buy one from GM dealer, the triggering voltage comes from the engine computer (ecm) and only supplies 5 volt. I think this is your problem. Try using an AC Delco alternator from the dealer and you should be fine.

ATS Tip:

If you want a wiring diagram for this charging system, please contact ATS.