Vehicle immobilization appears to intermittently engage

The dealer over-looked a bad ground connection. Remove and clean both battery terminals. remove and clean the engine ground, the ground from the engine to the chassis, engine ground from the engine to the firewall. Don't look at it remove and clean the connections. It is a classic ground (lack of) problem. The tech at the dealership just didn't know electrical basics.Good luck

Dealer cleaned battery terminals, supposedly cleaned all ground connections. Worked for about 1 week, then same thing. Replace all ground cables?

They probably didn't remove the ones on the engine--

Hi,
By accident, I discovered that the kill circuit for the 1997 Caravan is located in the Left rear Quarter panel inside compartment. In order to get to it, you must remove the Left rear seatbelt anchor bolt, the plastic panels in the left rear quadrant at the rear door & reach into the opening, usually covered by a clear plastic sheet with black goo (which has probably fallen down if your vehicle has been exposed to hot weather). The black plastic connector anchored to the body metal that has what appears to be a jumper plug installed (OR there may be a remote disable module plugged into the connector) is actually the disable connector. There is no cable departing this connector.
IF the connections in this plug have become corroded, this is probably where your problem is. I know that if you unplug this connector, you CANNOT start your vehicle!
If the problem is here, your best bet is to get someone who knows how to clean/ repair this type of connector, OR Take this info to your repair / dealer to follow up on your problem.
GOOD LUCK,
Horace