I'm not sure if I'm in the correct forum so I appoligize if I am not. On my 1996 Grand Caravan sometimes, but not every time you lock the vehicle using the clicker, the anti-theft alarm will activate usually about 20 minutes after being activated. You can use the clicker to unlock the van and if kept unlocked, everything is fine. This just started happening. I tried locking it in my driveway since I did not have to walk that far if it went off, but everything was fine. I went out sometime later, parked the van and locked it and it started beeping and flashing again about 20 minutes later. Right now as long as I keep the van unlock when parked I avoid this problem.

Got any clues what might be going on?

Thanks