#3 MM3 Flashing Instructions

This article will walk you through retrieving your tunes and writing them to your vehicle

You will receive your tunes via email from noreply@duramaxtuner.com. Download each attached file from the email and save them somewhere you'll be able to find them. It's important to ensure there are no extensions added to files such as -1 or (1) as the hardware will not be able to see them. If you receive a test file with an extension such as V2 or V3, this extension should be left in place.

MM3 Custom Tune Loading

  1. Insert your SD card into your windows computer
  2. Using Windows File Explorer open the SD card
  3. Double click the Custom folder
  4. Copy the files to the appropriate folders: ".ecm" files will go into the ECM folder, ".RTG" files go in the RTG folder
  5. Remove the SD card from the computer and install it into the MM3
  6. Turn your key to the Run position (key on, engine off)
  7. Touch the screen to turn the mm3 on
  8. Select ECM Tuning
  9. Select ECM
  10. Select Program Custom File to ECM
  11. Choose the tune you want to install
  12. Follow the on screen prompts


MM3 Tune Switching Instructions For 2004-2009 Trucks

  1. With your truck running, touch the screen anywhere
  2. Select the RT
  3. Select the tune you'd like to run
  4. Be sure to set the RT options to show send RT signal at startup, if you do not, the truck will default to the max effort tune each time it started

MM3 Tune Switching Instructions For 2011-2018 Trucks 

We've recently started providing RTG files in lieu of SOTF files for select trucks in this year range. If you receive your tunes in .ECM and .RTG format, you'll use the same switching method as 04-09 trucks and not the method listed below.

  1. With your truck running, touch the screen anywhere
  2. Select the switch icon
  3. Select the tune you'd like to run

MM3 Stock Tune Loading Instructions

  1. Turn your key to the Run position (key on, engine off)
  2. Touch the screen to turn the mm3 on
  3. Select ECM Tuning
  4. Select ECM
  5. Select Return Vehicle to Stock
  6. Follow the on screen prompts