How do you test for a faulty PDC with a scan tool.

I have an 02 grand caravan with 3.8 and when car get hot it will shut down and not do anything wont even turn over. Walt 15 minutes to an hour and it will start and run fine then just shut down. All relays are good Check all grounds that are clearly visible. PCM is realatively new. The only real thing I can find strange is that when car won't turn over you can hear ais motor clicking and relays in the pdc clicking with the key off. Only code that comes up is the p1684 battery disconnect code even if battery hasn't been unhooked. Car has too many miles to throw oarts at it but it does make a goo backup for my wife when running.