Speedometer not working, Brake, ABS, and Traction Control Lights On
Any, or all of these symptoms will appear on the 2013+ 6.7L Cummins when the tire size is set with the engine running.
To correct the issue follow the steps below:
-Turn the key on, but leave the engine off.
-Access the main menu on your GT device.
-Scroll down to "Diagnostics" and select clear DTC's.
-After you are back to the Main Menu, select the special functions option and navigate to "Tire size"
-Set your tire size to the correct size and follow the prompts
-Once complete, press "Go Back" until you see the main menu