Passenger Seat Belt Locked, Driver Seat Belt Unlocked.
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 the seat belt solenoid from pin 8 of the SCTM to ground for a reading of 50-60 ohm. If OK, replace the SCTM. If not OK, check for an open or shorted ground circuit and repair as necessary. Or replace the seat belt retractor if the open or shorted circuit is in the solenoid. The retractor is integral to the seat back and the entire seat back must be replaced if the retractor is found to be defective.