When towing (in some vehicles), a “Tow/Haul” mode provided crisper shifts to cut wear on the transmission, and reduced gear searching by holding lower gears longer. The system also selected lower gears when going downhill, to use the engine’s braking capability. In 2006, Chrysler claimed that the transmission had been “refined for higher-quality shifts;” it was strong enough to give the
Jeep Commander and Grand Cherokee class-leading towing capacity of 7,200 lbs. The changes included a redesigned solenoid to provide quieter operation when shifting (ending “solenoid clatter”), and a turbine damper to cut noise and vibration from the torque converter.
http://www.allpar.com/mopar/transmissions/545RFE.html