Folks, I've got a real head scratcher here. The van will randomly disconnect itself from electrical power, but if I manually unlock the door and open it enough to trip the door switch for the dome lights, it "wakes" the van from its "sleep mode" and everything operates as normal. When it "disconnects itself" from power, it erases all of the radio presets. So it's acts as if someone has taken one of the terminals lose from from the battery. It's all very random... Sometimes this will occur after just a few hours... Sometimes it's will stay powered up overnight and sometimes for a few days straight! ???? PLEASE HELP...

 

Some of these vehicles have a battery saver relay. Since we don't know what year you vehicle is unable to say for sure. If it has modules in it , it has a battery saver relay. They have been known to stick closed and allow the battery to drain or prevent modules from "going into sleep mode".
If it is a very late model vehicle sometimes other sources of signals will cause the modules to awaken. There could be a defective module in the network causing it also.
Problems like this are best solved using a quality scan tool. Voltage drop testing at the fuse panel can sometimes locate the system with the questionable module. There is a module in the instrument cluster that controls the radio and it can get a little hard to diagnose without a scan tool with bi directional capabilities.

 

Hanky, thanks for getting back to me. The van is a 98 E-150 conversion van with the 4.6 liter V8.