95' Pontiac Transport is possessed! Please help!

[matthollycart]

I don't know if anyone has any idea what is going on with our car, but maybe someone can help, because our mechanic, who is also our friend, can't figure it out, and before we spend a ton of money, we want to see if anyone might know. The other morning out of nowhere our van wouldn't start. we had AAA come and jump it, and as we drove it, things were going crazy. every time i hit the brakes, the power locks would unlock, and then lock every time i took my foot off. the power sliding door would not open, and we had to do it manually (and it was showing the door was open no matter how hard we shut it). the flashers and headlights were going crazy, and the lights inside the van would all turn on when i shut the van off, and you couldn't shut them off no matter what. we had the battery and stuff checked, but they are fine. but within 5 minutes of turning it off, the battery was dead again. also, after it died, it was making all sorts of clicking and tapping and chirping sounds, and the locks started going crazy again. our mechanic has tried many things. he has reset the power sliding door and stuff, and still cant figure it out. does anyone have any clue as to what this could be? is it possible its just something silly that is causing everything to go haywire? has anything like this ever happened to anyones transport? please help! (also, about a week before all this we had the motor in our driver's side power window replaced because it wouldn't go up and down well...could that have anything to do with it? although, our mechanic looked and saw everything was fine that he did to it)

[LMP]

Probably a wiring problem, like a corroded ground point or splice and this is not unusual after several years and water/salt intrusion. THis is hard to pinpoint. IF this is the case, it is a trial and error operation. I'd try to locate any wire that represents a "ground" (there are several that run across the vehicle) and try to measure actual voltage between some point on the wire and body sheetmetal. I use a needle to pierce through the insulation (of ground wires at different places) and connect to the voltmeter. THen run various accessories with engine either running or not and see if a voltage shows. There should be 0 volt or barely a few tenths of a volt. Of course this is tedious and can lead to nowhere after several attempts, but you can be lucky too.
There is a hard ground point near the starter. Locate also and test ground points near the computer unit, a senbsitive area. ...