2000 jeep grand cherokee laredo showing code p1686, p1687, p1688, geuges go down, all warning lights come on, with time, the geuges comes on, and the warning lights come off, all but the security key warning light.

Diagnostic Fault Code (DTC) P1686 has a generic description of "No SKIM Bus Nessage Received".
Diagnostic Fault Code (DTC) P1687 has a generic description of "No Instrument Cluster Bus Message"

P1688 is either not a valid code for your vehicle, or the manufacturer failed to provide specific information for it.
Basically, what is going on here is that you have a problem in your computer network communication bus. Or to put it more simply, the "phone line" is down. Your computers in your vehicle are having problems talking to each other.

"SKIM" stands for Sentury Key Imobilizer Module (AKA security module). The Instrument cluster and the SKIM are not communicating with the Powertrain Control Module (PCM) for sure, and possibly also not communicating with the Body Control Module (BCM). There may also be problems with other modules that share the same data lines.
This MUST be diagnosed with a scan tool that can access the entire computer network. You must find out which modules can communicate with the scanner and which ones cannot. This is necessary to determine the possible location of the fault.