Overdrive Solenoid
WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
If problem exists in overdrive solenoid, a diagnostic trouble code will be set. See TESTS W/CODES - 5.9L DIESEL article in the ENGINE PERFORMANCE section for testing procedure.