The simplest problem which could cause your Town and Country to be unable to communicate or connect to the smog machine could be a loose wire within the OBD II connector, or blown OBD communication fuse.
The most complicated fault could be a problem with the Engine Control Computer (ECU). If you can purchase an inexpensive Trouble Code reader (Pepboys or Autozone carry them) go ahead and try connecting to your Chrysler's ECU via the OBD II connector. If the scanner lights up as it's connected to your vehicle this will indicate there is power at the DTL (data link) connector and the problem is more then likely with the signal wire between the OBD II connector and the ECU. If the scanner does not light up this might indicate either a loose or disconnected power or ground wire at the connector. Check your Chrysler's fuse box for a fuse labeled DLC (Data Link Connector) in the passenger compartment fuse box.
