DT12 Automated Manual Transmission

Smooth Shift Performance, Durability and Ease of Operation

An automated manual transmission (AMT) combines a traditional clutch-actuated manual gearbox with a computer-controlled shift actuator and clutch. The best shift patterns are selected electronically to provide optimal power and fuel efficiency.

Brochures and Videos Maintenance Intervals and Warranties

1250-2050 LB-FT

Torque Range

12 Forward / 4 reverse


*DD: 14.93-1 / 14.93 OD: 11.67-0.78 / 14.96

Gear Ratios / overall ratio

DD=Direct Drive OD=Overdrive

An AMT is a proven technology used around the world. With computer-controlled shifting and clutch engagement, only two pedals are needed to operate the truck: the brake and accelerator. This makes the truck easier to operate and ideal for drivers of all experience levels.

More Specs

Engineered for Economy

Your fleet’s profitability depends on boosting fuel economy and increasing durability. Our engineers have looked at every opportunity to reduce fuel consumption and increase efficiency. They’ve built sturdy components and designed the DT12 to operate with limited wear and tear.

With more new drivers coming into the market, it’s critical to ensure your fuel economy goals are met and your trucks continue to last for years to come. With our easy-to-operate AMT transmission, drivers reach their optimal performance sooner, saving you money on fuel and improving driver comfort.

  • A pneumatic actuator engages the clutch and shifts the transmission, allowing for faster and smoother gear-shifts compared to electronic actuation.
  • Intelligent Powertrain Management (IPM) analyzes the route ahead and will accelerate, pre-select gears, eCoast and brake the engine to maximize efficiency.
  • Creep Mode improves low-speed maneuverability, making it ideal for backing up to a loading dock or in traffic.
  • A true two-pedal system and Shift Lever.
  • Advanced safety features like Auto Neutral, where under certain conditions, the transmission electronically commands “neutral” gear.
  • An optional rear-mounted PTO for specific applications in the bulk haul tractor-trailer market.
  • In the latest version of the DT12, the gears are “superfinished” for superior gear mesh and less parasitic loss.
  • Detroit™ Connect Virtual Technician is a factory-installed onboard diagnostic system that puts you in control of your business 24/7 and takes the guesswork out of powertrain repair by helping you manage your business more efficiently.

When combined with a specially-designed driver interface with enhanced cruise control, drivers have plenty of ways to further improve their fuel efficiency.

At Your Service

Detroit™ transmissions are spec’d, sold and serviced by an unmatched network of knowledgeable salespeople and expert factory-trained technicians at hundreds of Freightliner dealers throughout the United States and Canada.

Detroit offers outstanding parts availability and transmission owners also enjoy comprehensive warranty coverage — including fast, hassle-free processes — and expedited parts and service for critical downtime situations. Our transmissions come with a 5-year/750,000-mile standard warranty (and 3-year/350,000-mile standard warranty on the clutch).

DT12 Explorer

Click through the tabs below to learn more about the DT12 features and benefits. 


Transmission automatically disengages when the vehicle is coasting to help maximize fuel economy.

Skip Shift

The Transmission Control Module (TCM) sends electronic commands to “skip” unnecessary gears, helping increase acceleration to achieve cruising speed quickly and smoothly, and allowing the driver to accelerate in the appropriate “start gear” based on load and grade.

Powertrain Communication

A Common Powertrain Controller (CPC) optimizes high-speed communication between the Motor Control Module and the Transmission Control Module, improving operational efficiency throughout the entire powertrain.

Active Driveline Protection

The Transmission Control Module (TCM) calculates the torque wind-up in the driveline and regulates with engine torque control for enhanced driving comfort and less driveline wear.

Intelligent Powertrain Management

Intelligent Powertrain Management (IPM) pinpoints the truck's location and looks over a mile ahead to anticipate terrain. IPM will adjust cruise control, pre-select gears, eCoast and brake the engine to maximize efficiency into the road conditions ahead.

Total Weight

The aluminum housing and single countershaft help save weight, allowing for even more payload efficiency, while still offering excellent durability.

Power Take-Off

DT12 tranmissions are available with a proprietary rear-mount-only Power Take-Off (PTO) that may allow customers in the bulk-haul tractor/trailer market to operate applications using liquid trailers, dry goods, wet goods, and moving floors.

Model Options

Designed for construction, distribution, dump, fire and emergency, government, motor home, oil & gas, refuse, and regional. 


New Cascadia®
Western Star
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Integrated Detroit™ Powertrain


The integrated Detroit™ Powertrain delivers the performance and dependability you need to run your business efficiently. Detroit has designed, engineered and manufactured the engine, transmission and axles to work together seamlessly, providing the optimal powertrain solution for your business needs. The integrated Detroit Powertrain is available in the new Freightliner Cascadia®, the original Freightliner Cascadia Evolution and the Western Star® 5700.


  • Integrated Communications Benefits: The DT12™ transmission links engine to axles, and communicates with the DD13® and DD15® on an integrated electronics network to share damage-reducing information such as clutch overloading and driveline protection.
  • Super-Finished Gears: Tightly-spaced 12-speed gearing, now with "super-finished" gears in the new DT12™ available for the new Cascadia and Western Star® 5700XE, improves low-speed maneuverability, making the Detroit™ Powertrain not only strong and efficient, but also smooth and safe to operate as well.
  • Intelligent Powertrain Management (IPM): The DT12™ uses information from a topographical map to manipulate both engine and transmission functions, taking advantage of the truck's surroundings. IPM4 refines the parameters of this technology, making the truck even more capable of utilizing its surroundings efficiently.
  • Transmission Benefits: The DT12's direct drive and over drive gearing, along with eCoast, are integrated with the downsped engine — which now idles at a lower 500RPM when off-throttle — for optimized fuel economy.



  • 2017 Greenhouse Gas-Compliant Engines: The flagship DD13® and DD15® engines are compliant 2017 Greenhouse Gas (GHG17) standards.
  • Downsped Engines = Improved Fuel Economy: The DD13® and DD15® with downsped 400 HP and 1750 lb/ft rating deliver greater horsepower and torque at lower RPMs, keeping your truck in top gear longer while cruising at more efficient engine speeds. Lower engine speeds reduce the number of fuel injections, dramatically improving fuel economy.
  • Six-Blade Engine Fan: The six-blade fan reduces power draw without sacrificing cooling capabilities.

Steer Axle

  • Numerous Steer Axle Advantages: Detroit™ steer axles offer rugged strength in a lightweight package, and integrate optimally with the other components. They are designed for the life of the axle, with multiple ratings available for tailored weight distribution.
  • Superior Maneuverability: The Detroit™ Powertrain's state-of-the-art steer axles provide a 55-degree wheel cut for remarkably nimble maneuvering. 
  • Needle Bearings Improve Durability: With needle bearings instead of bushings, they won't damage the king pins, and offer increased durability.

Tandem Rear Axle

  • New Axles Designed for Fuel Economy: To provide optimum efficiency and performance, the Detroit™ Powertrain includes an all-new axle specifically designed to integrate with the downsped DD13®, DD15® and DT12™, resulting in rock-solid reliability and durability.
  • Faster 6x4 Axle Ratios: The 6x4 configuration is available for applications requiring 4-wheel drive and superior traction. A variety of faster axle ratios are available, ranging from 2.41 to 2.28.
  • Faster 6x2 Axle Ratios: The 6x2 configuration boasts a 2.28 ratio, allowing the DD15 to turn lower RPMs with the truck cruising at the same speed. It pairs perfectly with the low RPM torque curve and direct drive transmission. This means it can cruise in top gear longer, for better fuel efficiency.
  • Lighter 6x2 Axle: The 6x2 axle configuration incorporates a non-driven tag axle on the tandem, reducing total weight (by 380 lbs) and the number of moving parts, delivering better fuel economy.
  • New Optional Axle Lubrication Management (ALM): The tandem rear axles feature an optional axle lubrication management (ALM) system that actively regulates the oil level at the ring gear and friction-loss optimized pinion bearings to reduce friction and parasitic loss, extending gear life and further improving fuel efficiency.



  • 1-Box: The 1-Box is a complete aftertreatment emissions system that combines the SCR catalyst, the Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and Diesel Exhaust Fluid (DEF) all into one simple component.

Brochures and Spec Sheets

Detroit Powertrain Product Overview Guide (Freightliner New Cascadia) Detroit Integrated Powertrain Brochure Detroit Powertrain Product Overview Guide (Freightliner Cascadia & Western Star 5700)

detroit virtual technician remote

If maintenance issues come up on the road, you can count on Detroit Virtual Technician remote on board diagnostics system to let you know how serious the fault code is, where the nearest part you need is located, and when you can get into the next available service bay, and then it can even schedule your repair appointment for you.

Connect Today

Learn more by visiting the nearest Freightliner or Western Star dealership.

Find Nearest Dealer

Brochures and Spec Sheets

Detroit DT12 Brochure Detroit DT12 Driver Card


Detroit DT12 Fuel Economy Video Detroit Original DT12 - Downhill Overspeed Training Video Detroit New DT12 - Downhill Overspeed Training Video Detroit DT12 - Western Star Intro Training Video Detroit DT12 - Western Star Creep Mode Training Video Detroit DT12 - Western Star Hill Start Aid Training Video Detroit DT12 - Western Star Transmission Control Training Video Detroit DT12 - Western Star Kick Down Training Video Detroit DT12 - Western Star Driving Modes Training Video Detroit DT12 - Western Star eCoast Training Video Detroit DT12 - Western Star Engine Braking Training Video Detroit DT12 - Western Star CC Limit Training Video Detroit DT12 - Western Star IPM Training Video Detroit DT12 - Western Star Descent Control Training Video Detroit DT12 - Western Star Auto Neutral Training Video Detroit DT12 - Western Star Outro Training Video Detroit DT12 - Freightliner Intro Training Video Detroit DT12 - Freightliner Creep Mode Training Video Detroit DT12 - Freightliner Hill Start Aid Training Video Detroit DT12 - Freightliner Transmission Control Training Video Detroit DT12 - Freightliner Kick Down Training Video Detroit DT12- Freightliner Driving Modes Training Video Detroit DT12 - Freightliner eCoast Training Video Detroit DT12 - Freightliner Engine Braking Training Video Detroit DT12 - Freightliner CC Band Training Video Detroit DT12 - Freightliner IPM Training Video Detroit DT12 - Freightliner Descent Control Training Video Detroit DT12 - Freightliner Auto Neutral Training Video Detroit DT12 - Freightliner Outro Training Video Detroit DT12 - Inclement Weather Training Video Detroit DT12 - IPM4 Training Video Detroit DT12 Product Video Detroit New DT12 - IPM Intro Training Video Detroit New DT12 - IPM and New Cascadia Dash Display Training Video Detroit New DT12 - IPM Predictive Acceleration Mode Training Video Detroit New DT12 - IPM Crest Coast Mode Training Video Detroit New DT12 - IPM Steep Hill Crest Coast Mode Training Video Detroit New DT12 - IPM Dip Coast Mode Training Video Detroit New DT12 - IPM Driver Safety Considerations Training Video


Detroit DT12 Front Image Detroit DT12 Back Image Detroit DT12 Left Profile Image Detroit DT12 Right Profile Image

Detroit Connect Portal

The Detroit™ Connect portal is easy-to-use, one-stop-shop for all vehicle performance data gathered, transmitted and analyzed by Detroit Connect.  The portal gives you access to insights delivered by  Detroit Connect Virtual Technician℠. The Detroit Connect portal will also give you access to new features, such as Remote Updates, and Analytics, available late 2017.

Detroit connect portal login


DDCSN serves as both a public customer website and secure service portal to access DETROIT branded product service and parts information, tools, training, and more. Here you can access a wide range of product literature such as operator mauals, warranty booklets, and even service bulletins. You can also find parts catalogs, sales and marketing programs, webinars, and much more.


DTNA Connect Portal

DTNA Connect is the starting point for working with all brands and franchises that fall under the Daimler Trucks North America umbrella: Detroit, Thomas Built Buses, SelecTrucks, Sterling, Freightliner, and Western Star. Here, you can access the full spectrum of online applications, resources and tools you need. Whether you use DTNA online resources to complete repairs, purchase parts, submit warranty claims, spec new vehicles or track the status of your truck orders, DTNAConnect streamlines the tasks and activities that are part of your daily work routine.

DTNA Connect Portal Login