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.

AUTOMATIC TRANSMISSION:

The Power Take-Off (PTO) Switch in the Upper Switch Bank is located on the Dashboard. When the PTO Switch is turned on it sends a hard wired signal to the Powertrain Control Module (PCM). This signal is a request to turn on the PTO. Once this signal is received and all other monitored conditions are met, the PCM sends a BUS command to the Transmission Control Module (TCM) to enable the PTO/AUX 5 relay. The PTO/AUX 5 Relay is located in the Auxiliary Power Distribution Center (PDC). The Aux PDC function chart refers to it as: 'Relay 07'. The TCM sends a ground signal (low-side driver) on the PTO Relay Enable circuit to activate the PTO relay. The relay then sends B+ supply voltage out to the PTO system. The Vehicle System Interface Module (VSIM) monitors for PTO engagement via a pressure switch input signal. The VSIM reports the PTO status to the PCM over the CAN Bus.

MANUAL TRANSMISSION:

The Power Take-Off (PTO) Switch in the Upper Switch Bank is located on the Dashboard. When the PTO Switch is turned on it sends a hard wired signal to the Powertrain Control Module (PCM). This signal is a request to turn on the PTO. Once this signal is received and all other monitored conditions are met, the PCM sends a 12-volt (hi-side driver) signal on the PTO Relay Enable circuit to activate the PTO/AUX 5 relay. The PTO/AUX 5 Relay is located in the Auxiliary Distribution Center (PDC) The Aux PDC function chart refers to it as: 'Relay 07'. The relay then sends B+ supply voltage out to the PTO system. The Vehicle System Interface Module (VSIM) monitors for PTO engagement via a pressure switch input signal. The VSIM reports the PTO status to the PCM over the CAN Bus.