Possessed dash
 

Our 2000 Grand Cherokee has some jumping guages for a week or so, sometimes no problem, sometimes jumping on and off. At first only the oil/gas/temp would go off and back on. Then the speed/rpm started in but never all at once. Now, every guage is off and all the idiot lights are on. A/C blows but not cold, computer shows direction but not the outside temp and the windows wont go up or down. For a couple days I could use the windows if I did it in the first couple seconds of starting the car, I would check the gas guage too!
Now everything is out.
Help! I've checked online and the two suggestions I find are battery cable and the PCM. We've cleaned the battery cables and retightened them but no change.
Any ideas?

Your symptoms are not controlled by the PCM or any one module alone. See module duties here, scroll down for full view:http://www.wjjeeps.com/modules.htm My guess is you have a faulty ground issue, rather than several modules going bad at once.

possessed
 

So I'm sure this is a stupid question for you, but I've searched all over online, where are the major grounds? Where would I start?
Cant find a list of ground points.

It sounds like the driver door module has lost it's ground and is grounding through the databus.

Pop off the wire accordion boot in the driver door jamb and look for the broken black wire.

Just pull it from the door and jamb and slide it back where you can look at the wiring.