I have a 2000 JGC 4.7 V8 and the instrument cluster dies 30 seconds after start and all the warning lights come on. The first light to show is the key with the circle followed by others. It starts and runs fine and has never stalled. I've checked door wiring and changed PCM but problem remains. If I unplug the alternator the cluster works and all is well. When measuring pin 2 voltage it is constantly fluctuating quickly between 3.8 and 5v before the gauges die and everything works. As I am watching it; the voltage jumps to 7.30v after about 45 seconds and stays there (no fluctuating) and it is at that time that my gauges die and I hear the door modules click and the windows and locks no longer work. If I unplug the instrument cluster at this point; the voltage begins fluctuating again (in the same range) but the windows and locks start back working normally. Given this; I ordered another cluster and installed it. Initially everything worked well for a day, but it is now back to what is was doing with the old cluster. I thought it was the alternator originally and installed a new one so the alternator is new. Thank you in advance for any help!