Theory Of Operation

WARNING: This page is about a different car, the 2024 RAM ProMaster EV. However, it is still accessible from the selected car via links, so may be relevant.

The Quiet Vehicle Pedestrian system consists of the BCM, the Electronic Pedestrian Protection Module (EPPM) and the Pedestrian Alert Speaker Module. The BCM receives ignition status, vehicle speed, transmission gear position and engine status over the Controller Area Network (CAN) bus. The BCM sends Local Interface Network (LIN) signals to the EPPM for vehicle speed and sound control. The EPPM includes the front speaker and is hardwired to the rear Pedestrian Alert Speaker Module.

The EPPM outputs sound according to vehicle speeds greater than 0 mph/kph, gear position and OFF state of the engine. EPPM speaker volume and tone monotonically increases or decreases in frequency proportional to vehicle speed in forward and reverse direction.

The EPPM system is active when:

the ignition switch is in the START or ON positions.
the engine is OFF.
the vehicle speed is between 0 and 35 km/h (0 and 22 mph) in forward and reverse.

The VPA system is not active when:

the vehicle is in park.
the engine is running.

The EPPM receives 12 volt battery current on a fused ignition switch output (RUN-START) circuit through a fuse in the Power Distribution Center (PDC). The EPPM receives ground through the body wire harness connected to the body sheet metal. These connections allow the module to be operational whenever the ignition switch is in the START or ON positions.