MM3 Instructions


  1. Begin installation by laying out all the supplied components.

Start by installing the J1939 data link connector (on the fly cable). The connector can be found on the firewall side of the bottom of the trucks air intake manifold on most trucks. Carefully route through the firewall using a grommet. Plug into the communications module. Next, select a mounting location for the MM3 monitor. Connect the Micro USB cable to the monitor and the communications module. Finally, install the OBD2 cable to the communications module. Then connect the OBD2 cable to the trucks OBD2 port. It is important that this is the final step in the installation. Installation is now complete!


  1. Create a stock file for the truck by doing the following: Switch your key to the ON position(DO NOT START TRUCK) . Enter the main menu by pressing the (…) button at the top center of the display. Next, select the (ECM Tuning/DTC) select (ECM) then click (Get Stock File For Truck). The MM3 will write the stock file to the MicroSD card into the folder labeled (Custom). Remove the MicroSD card from the MM3 monitor, and insert the SD card into a computer using the supplied USB adapter. Once the computer recognizes the SD card, select the (custom) folder. There you will find a file named “STOCK.MM3”.  Copy that file onto the desktop of your computer and then attach it in an email  to your tuner:


  1. Once you receive your tune(s) from your professional tuner: 1. Plug the SD card into the computer using the supplied USB adapter. Download and save the attachments to your desktop or documents folder. 3. You may have 2 file types on your desktop/documents.  One will be a (.ecm) file.  This file will need to be put into the (ECM) folder Inside the (CUSTOM) folder on the SD card. 4. You may also receive( .rtg) files These files need to go into the (RTG) sub-folder also within the (CUSTOM) folder.   5. Once you have the files in the appropriate folder install the SD card into the MM3 and proceed to the next section.

Attention! DO NOT re-name any of the files that your tuner supplies to you. This can cause errors!


  1. Carefully insert the Micro SD card back into your MM3. Then navigate to the main menu (…) once again and Select the (ECM Tuning/DTC) option, then (ECM) followed by (Program Custom file to ECM) Then select the file name that appears (example.ecm).  Then agree to the speed limiter setting and select Program Custom file to truck.  The MM3 will now flash in the base file and unlock the ecm.  This will take approximately 5-7 minutes.


  1. Once the download is complete start the truck. To change power levels and use the RTG’s (REAL TIME GROUPS) , press the “RT” button on the top right of the MM3’s display.  This will take you to the menu where you will select “RT custom adder”.  Next you will select your power level (TOW, Street, Race, ETC…)  Once you have selected the desired power level the MM3 will load the changes into the ECM. For the RGT’s this process usually takes around 5-15 seconds depending on year of truck and file size. Once the RTG selection is complete the MM3 will return to the gauge screen.



* In the “RT” menu section you can choose to send the RT file only once, or at every startup.