TSB 18-014-01
All Performance enhancement for severe cold weather environments.
This bulletin applies to all Ram trucks equipped with a 5. 9L 24-valve Cummins diesel engine with a 49-state emissions calibration and an automatic transmission. The bulletin describes how to selectively erase and reprogram the Powertrain Control Model (PCM) with new software (59t7a). The problem addressed by the PCM reprogram is a hard starting and/or idle speed fluctuations condtion.
Cummins 24-vavle engines used with automatic transmissions can be severely affected by the use of sub-grade #1 diesel fuel when ambient temperatures are below 0°C (32°F), typically prevalent during the Winter months in Alaska, Northwestern Canada, and similar climates/temperatures elsewhere.
This change will have no effect on performance during warm weather or when standard grade diesel fuels #1 or #2 are used.
Vehicles with 49-state certification can apply this calibration if needed. The calibration can be changed back to the original calibration if desired.