2007 Tahoe LT 2WD 5.3L Woes...
 

07-03-13 / Here is what occured:

I was sitting in the parking lot, idling. Gradually, the A/C shut off, then the radio, and all the gauges (Oil, Speedometer, Temperature, and even the DIC display) simply shut off. I thought it was the battery, so I began driving around the parking lot, trying to rev some life into it. The voltage gauge needle began to dwindle down little by little, the truck jerked, trying to keep herself alive.

I had no choice but to park the Truck to decide what the problem was. I figured it was the battery, not even having any general knowledge of engines, shame on me, I went and bought a new battery, came back and installed it. The truck started up fine, and I drove about 4-6 miles and the same thing began happening when I restarted the truck and wasn't even a mile up the street, the same thing occurred. Everything began to shut off on its own while I was still driving. And again, the voltage gauge needle with a NEW battery dwindled down. Fortunately, I was able to pull in to an Auto Zone.

They tested the battery, which of course was good, but wouldn't hold the charge. The Auto Zone guy assumed it was the alternator, which COULD be the case, but my Wife's Grandfather was a Mechanic for 23 years for GM, so I figured his advice would be more legit. His theory is that there is a short in the system somewhere.

I previously took the truck to the dealership to have the TSB Recall System Upgrade put in, (before all this took place, this was almost a year ago.) I had to pay for that service since the TSB was already expired for a free fix.

Sometimes the doors won't unlock when I put the truck in park. I figure it's the Short too.

Any advice, anyone else experience the same issue? Thanks in advance.

I'd get the alternator checked to to make sure its okay.

Alternator....
 

You were right, the Alternator was shot. Zapping the battery down, runs like a champ now.