Both Seat Belts Lock And Unlock With The Ignition Switch On Or When The Driver Door Ajar Switch Is Activated But Not When The Passenger Door Ajar Switch Is Activated.
WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
Using a DVOM, check from the SCTM to the passenger door ajar switch circuit for an open or short to ground. Check pin 3 of the SCTM 13-way connector to ground for continuity. If no continuity, check for open or shorted circuit and repair as necessary or replace door ajar switch. If OK, replace the SCTM. System will function improperly from the effected door.