Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Variable Geometry Turbocharger (VGT) is electronically activated by the Turbo Actuator. The Turbo Actuator is a smart device that receives information via the CAN BUS from the Powertrain Control Module (PCM). The Turbo Actuator performs it's own diagnostics and reports failures back to the PCM using the CAN BUS. The PCM then decodes the error message and converts it to a fault code. This monitor is a two trip fault. The MIL lamp will turn off once the diagnostic runs and passes in four consecutive drive cycles.