Theory Of Operation

WARNING: This page is about a different car, the 2015 RAM 3500 HD and 2015 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The Brake Pedal Position (BPP) Sensor is hardwired to the ABS Module. The ABS Module broadcasts the BPP Sensor signal information, as well as the Master Cylinder Pressure Sensor signal information out over the CAN Bus. The Master Cylinder Pressure Sensor is internal to the Hydraulic Control Unit (HCU).

The Master Cylinder Pressure (MCP) Sensor signal is utilized to support Brake Pedal Position Rationality and Brake Pedal Sensor Diagnostic. Autonomous braking systems such as Active Cruise Control (ACC+) have the potential to defeat the Brake Pedal Position Rationality diagnostic as the vehicle can be brought to a complete stop without depressing the Brake Pedal, thus false failing the rationality. The Brake Pedal Position Rationality needs the MCP Sensor Signal to discern if any autonomous braking system is active. The MCP Sensor only measures the brake system pressure applied by the vehicle operator and is not affected by ABS, parking brake or autonomous braking systems.