Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. 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 Powertrain Turbo Actuator. The Turbo Actuator is a smart device and receives information via the J1939 BUS from the Powertrain Control Module (PCM). The Turbo Actuator performs its own diagnostics and reports failures back to the PCM using the J1939 BUS. The PCM then decodes the error message and converts it to a fault code. The PCM lights the MIL lamp immediately after the diagnostic runs and fails. The PCM will turn off the MIL lamp immediately after this diagnostic runs and passes in four consecutive drive cycles.