Looking at some 06-09 2500's and some have light load button down near console, is this for engine brake?
From the manual.
The Tire Pressure Monitor System (TPMS) “LIGHT LOAD” reset switch will allow the driver
to switch between the MAX LOAD INFLATION PRESSURE (COLD) low pressure warning
threshold and the LIGHT LOAD INFLATION PRESSURE (COLD) low pressure warning
threshold depending on the vehicle's load condition. The tire and loading information label
defines the recommended front and rear cold tire inflation pressures for the vehicle when
operating in the MAX Load condition. A SUPPLEMENTAL TIRE PRESSURE
INFORMATION label is also included defining Light Load tire inflation pressures when
operating in the Light Load condition. When the “LIGHT LOAD” reset switch LED is ON,
the TPMS is using the light load inflation pressure (cold) low inflation warning threshold.