'99 Battery/Alternator Issues

[Friedtater22]

My alternator is not pulling enough amps to charge my battery. It's only pulling around 11.9 amps. I just recently bought a new battery, replaced the alternator, the plug that goes into the alternator, the spark plugs (gapped to 0.60), and plug wires. When tested, the alternator fails while connected to my Tahoe, but when I remove it and have it tested, it passes with no problem. Also, my check engine light just started flashing. I had it checked a few days ago and it was only throwing a C0281 code, but that was before it started flashing. I am at such a loss. I don't even know where to begin to look! Any help or suggestions would be greatly appreciated.

 

[lesterl]

Check all your grounds and battery connections..... C0281 Is a brake light switch code. http://www.fixya.com/cars/t3736891-code_c0281_fix

There are several grounds, taking voltage drops between the battery + to the alternator + post while charging and from battery - to engine ground can indicate a problem with the wiring.

FYI Alternators don't put out MAX current all the time.. They produce a varying amount based upon demand and upon engine RPM. Try turning your lights on and your blowers on and checking current draw again.