2000 Grand Cherokee Jeep RPM and Speedometer not working

I had a battery die on my 02 grand Cherokee, all the gauges went wild, needles bouncing from left to right crazily! You need a new battery!

Have you checked all of the fuses with a meter to see if they have power ?

your idle air control valve is going out located behind the throttle body.

google grand cherokee forums join a few and post ques there

First thing is to check all your fuses. It could be as simple as a blown fuse.
Thanks,
Lee

To Larry Crowley,
Did you ever correct the problem to your 2000 Jeep Grand Cherokee and did you in fact determine that the problem was in fact the Body Control Module (BCM)?
I too have a 2000 Jeep Grand Cherokee Ltd with 162,000 miles. Up until just a few months ago, I never had any major problems with the car however in early December one evening the car was turned off and parked in my garage and the horn just went off out of nowhere, a solid horn...it was deafening! We unplugged the battery for the night so it wouldn't drain the battery. The next day I took the car to the mechanic who replaced the horn switch and relay. We thought that had fixed the problem. An hour after I left the mechanic with the car both the BRAKE and ABS lights on my dash went on and my speedometer stopped working (very scary to drive that way). When I stopped the car and went to lock it with my keyfob, the solid horn went off again so obviously the problem was not the horn switch and relay!?!? Over the past few months I have had my car to three different mechanics as well as the Jeep dealer and they have all concluded that the problem must be the BCM but they said that the only was they can properly diagnose the car is if it is acting up with the above mentioned symptoms while in the shop. Unfortunately it only acts up intermitently, not all the time. I am at such a loss. Currently we have removed the fuse for the horn so I am driving with no horn which is extremely unsafe! I look forward to any advice you have in this regard. Thank you!

could be an idle controll sensor...maf sensor or o2 sensor....run a good carb/fuel ingector cleaner through with with some high test gas, do this for you next 2 fill ups, one can of cleaner per full tank...if it doesnt work.. then one of those senors is playing tricks with ya...In worst case the timing belt is slipping..
hope this was helpful !

Speed Sensors, I think their are a few

if the battery is weak,it does not have the rpm needed for the computer to start the vehicle.
if your immobilizer is kicking in,it will not start.
get the electrical checked out.