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Allison A40 TCM with DDP Trans tuning

06-08 Duramx Allison Replacement A40 TCM




The A40 Transmission Control Module found in the 2006-2008 2500/3500 Duramax is prone to failure. The internal circuit board fails and is not serviceable.  When this failure occurs the truck owner may experience Range Shift Inhibited, Service Brake System, Service stabilatrak, loss of gear shift indicator, slamming into Drive or Reverse, and DTC U0101 for loss of communication with TCM.

This repair at a dealership can cost $700-1000 on average plus the tow bill to get the truck there.  Some may find new TCMs on ebay, but they are blank and still need the dealer to program it.  Then there is that tow bill again. Both options are costly and give you a stock TCM calibration when you're done.  Who wants that?

We offer our Pre Tuned A40/T14A TCM that is programmed with our Custom EFILive calibrations.  This plug and play TCM will improve the shift quality and drive experience with your truck.  We raise the shift points for 4th, 5th and 6th gears to keep the engine in a better rpm range to prevent it from lugging.  This is nice especially if you have larger tires.  We adjust torque converter lock up strategy to put the power to the ground sooner under full throttle and keep it locked during shifts.  We adjust the torque limits to allow the truck to make more power above 3000 rpm at full throttle and improve throttle response when leaving a stop. 

This TCM is delivered right to your door and takes roughly 5 minutes to install. 

No core required. 

Lifetime Warranty


***Will Not Work in 4500 or 5500 trucks.

Dan's Diesel Performance part nubmer: DDP-A40