Theory Of Operation

For this vehicle build configuration when the PTO switch on the Integrated Center Stack (ICS) is turned on it sends a hard wired signal to the Powertrain Control Module (PCM) requesting the PCM to turn on the PTO. Once received and all the monitored conditions are met, the PCM then sends a BUS command to the Transmission Control Module (TCM) to enable the PTO relay to turn on. The TCM grounds the PTO relay control circuit at PIN 86 of the PTO relay allowing the system to turn on. The PCM monitors for PTO engagement via a pressure switch signal BUS message from the VSIM to verify operation. The TCM monitors the PTO relay control circuit and sets DTCs for faults related to that circuit.