• Home
  • ATS TCM Upgrade, A50 to T87, 2011- Early 2015 GM 6.6L Duramax

ATS TCM Upgrade, A50 to T87, 2011- Early 2015 GM 6.6L Duramax


SKU: 601-130

ATS TCM Upgrade, A50 or T14 to T87
Fitment: 2011- Early 2015 GM 6.6L Duramax


The A50 and T14 TCM that is used to control the Allison 6-speed automatic transmission is the weak link of the Allison transmission.  This is due to delicate thin wires inside the TCM that contact one another overtime and short-out the entire module.  In 2022, Allison sent out a letter (SIL 15-1K2K-22) announcing the discontinuation of support for the A50 and T14 TCMs.  This effectively left over 10,000 Duramax owners out of their trucks.  Some of the warning signs of a failing TCM are messages including “Service Brake System”, “Stabilitrak Service Required”, “Range Shift Inhibited”, “Service Brake System”.  So we got to work developing a solution utilizing our Translator® technology found in the ATS Allison Conversion to help get these trucks back on the road, shifting and holding power even better than before, ASAP!


The A50/T14 TCM have been used in all GM Duramax/Allison Diesel Trucks produced from 2009 to 2017. ATS is excited to release the new GM Allison T87 upgraded TCM module.  The upgraded TCM comes in an assembly including our Translator® module that also has our Co-Pilot transmission functions built in. The Co-Pilot function increases the power holding capability of the factory transmission enabling the Allison to handle much heavier loads and shift under much higher power levels without the fear of damaging the clutch packs of the Allison transmission. This is a substantial upgrade in power, performance and reliability over the original factory A50 and T14 TCMs.


The ATS T87 Conversion now provides a much more aggressive factory exhaust brake over the factory A50/T14 TCM. We were able to increase the exhaust braking ability in two areas. First off, we enabled all of the additional tables that the T87 TCM offers that are designed to operate the standard exhaust brake function and the Tow Haul exhaust brake function, these two tables are specifically designed to manage the exhaust brake and provide an aggressive down shift schedule. Secondly, we are able to command the ECM to use the full exhaust braking function of the ECM, the factory A50/T14 TCM limits this ECM from commanding the full exhaust brake. When the ATS T87-Translator upgrade is installed we enable the ECM to apply the full exhaust braking effort the engine has available. The combination of the T87, custom TCM calibration and Translator module maximizes the Transmission and Engine/Turbo exhaust brake to provide the most aggressive exhaust braking yet! This function not only provides a safer level of driving but it gives superior engine braking reduction with heavy loads.


No core charge required, all components are brand new.  GM has released a “Band-Aid” fix which repairs the problem but does not fix the root cause.  This repair requires a trip to the dealership which can then take up to a week or more to make it through the service department, costs nearly as much as our upgrade, continues to use the 10 old outdated TCM technology and leaves the same components vulnerable to reproducing the same problem with no warranty on the repair.



  • Works with stock or modified trucks
  • Controls and increases line pressure
  • Direct replacement, no permanent modifications required - plug and play OEM quality harness and module
  • Found on the current L5P 2023 Duramax, the T87a TCM has a much faster processor than the A50/T14 TCMs and that equates to better shift quality, faster shifting and overall improved drivability
  • Increases throttle response
  • Fuel economy and MPG improvement
  • Updated shift points to keep the engine within desired RPM range
  • Better torque converter lock-up response
  • Increases life expectancy of the Allison LCT1000 Transmission
  • Brand new, factory sealed TCM and Translator/Co-Pilot Module
  • Our complete wiring harnesses use state of the art technology and configuration
  • Can be used with any Engine Control Management programming
  • Direct Replacement for AC Delco:TCM 24256861 25978353 15117030



  • New T87 TCM that is unlocked and has a custom ATS calibration pre-installed that optimizes the performance of the Allison transmission. 
  • New Translator® module that has the Co-Pilot transmission pressure function enhancements built in. The Co-Pilot functionality allows the factory Allison transmission to handle higher power levels and much better durability.
  • New Digital Speed sensor
  • New Digital Turbine sensor
  • Mounting Bracket
  • Wiring Harness

Instructions Coming Soon

Ratings & Reviews

5 reviews

  • 4 stars
  • 0 reviews
  • 3 stars
  • 0 reviews
  • 2 stars
  • 0 reviews
  • 1 star
  • 0 reviews
6/6/2023 7:56 pm

Satisfied Customer

by Matthew Moore

This module does everything they say it does I was very happy to get my truck back on the road going to really put it to the test this weekend hauling my 42ft fifth wheel this weekend to Erie pa can’t wait to see how it performs will write another review when I get back

8/7/2023 10:53 am

OMG! I have a new truck!

by Brian

I'll gladly be the first to review this amazing upgrade! I have a 2011 3500 Duramax 4x4 and was hesitant to pay $3000 for this conversion, but now I can say I have absolutely no regrets! After the learning process, which only take a few miles of driving, my truck drives like it's got a brand new transmission! The shifts are so smooth you can barely feel them and it holds gears going down hill so much better! I've been tracking my mpg and the best I could get overall before this upgrade was 14mpg. In a matter of 50 miles of everyday driving I'm already above 17mpg overall! It made me realize what piece of junk the original tcu was! I love my truck again! Don't wait, this is THE upgrade for this model year truck! You won't regret it.

12/13/2023 10:21 am

T87 TCM Upgrade!

by Brandon Ball -

ATS has been nothing but stellar to work with! My truck was down for 10 months thanks to GM making poor quality parts which they then stopped manufacturing after the immense amount of defects and failures. My truck is a 2013 GMC 2500 with 50,000 miles on it and it became a giant paperweight without ATS coming to the rescue. Their TCM upgrade kit is unbelievable. My truck gets better gas mileage, drives smoother, and is all around a new truck with this kit! Nathan, and Mackenzie were great help throughout the whole process with installation questions, warranty questions, etc. They even made a new update that works even better now and shipped me a updated part free of charge! Can't recommend them enough, they have a customer for life!

1/8/2024 2:37 pm

Thank you ATS for this TCM!

by James

My truck is a 2013 GMC Denali 2500 with 100,000 miles. It sat for several months. I was getting frustrated with the scalpers and sent my TCM to a company for repair, witch didn't work & I never heard back from the company. When I received this TCM. Installation was easy. Once I got it through the learning process it works amazing!!! My truck has been back on the road since July 2023 and has been running great! Thank you ATS!!

3/10/2024 9:03 pm

This upgrade is a must.

by Neil

The tcm changes everything.
Better shifts. Goes into overdrive way sooner then the factory one did saving you money on fuel. Traction control works better,faster. Convertor lock up is improved creating better feed back especially if your having fun on the dirt roads. Downshifts and upshifts faster making your truck faster and more efficient. I would recommend to anyone even if your factory tcm isn't giving you trouble.