Chrysler Repair: volt meter, jeep grand cherokee, grand cherokee

Question
The volt meter started dropping off to 0 when it was cold and damp, if I shut Jeep off and restart it comes back up, this might happen one or two more times then stays on. Now it seems that it does it all the time, now when I start the Jeep cold the gauge starts at about 1/4 way up and I have to leave all electrical stuff off until gauge reads normal, but when I turn stuff on and drive the gauge will probably tank. when I'm waiting for the gauge to come up if I press the accelerator the gauge will slowly drop and then I have to wait for it to start moving up again. Sometimes I've driven at night with meter reading 0 with the lights, wipers, heater on for an hour, get home and next day truck starts so I think it's still charging no problem. I've seen web sights that point at mounting screws on the PCM, maybe a bad ground somewhere, maybe a contact on the BCM. Any thoughts. Thanks in advance. DON   1997 Jeep Grand Cherokee  5.2L.

Answer
Hi Don,
My thought is that the gauge may be flakey itself or there is a bad connection to it from the point where it gets its reading. The gauge should reflect the actual voltage of the system, and if that were truly 0, and even a fraction of the normal reading then I would believe that nothing would run and the engine would die. I don't have a manual for any Jeeps prior to the '04 so I am just basing this on common sense, where I am assuming that it is a voltmeter gauge that is in the cluster. The best thing to do would be to measure the voltage across the battery with a working voltmeter and see how that compares with the dash gauge. It should ideally be arount 12.6 to 14.0 depending upon the rpm and the state of charge of the battery.
Once you know what is truly going on we can consider what to do if anything.
Please 'rate' my answer (see below).
Thanks,
Roland