The LMM Duramax 2500/3500HD's Allison TCM is known for issues. These issues can cause limp mode, loss of PRNDL display, and can trigger check engine lights. The DuramaxTuner Pre-Tuned Replacement TCM is a brand new and upgraded TCM for your stock 2009 and 2010 Allison 1000 A50 Transmission Control Module. Your new TCM will arrive pre-programmed for your VIN and includes Duramax Tuner's custom TCM Tuning. This tuning features refined shift schedule that takes advantage of the wide torque curve, improved converter clutch engagement settings to allow lockup under heavy loads, torque limitations adjusted to allow high RPM fueling, and 2nd gear start in 4wd low range. This tuning is great for towing and performance applications.