Description - Diesel Exhaust Fluid Pump: Operation

The Diesel Exhaust Fluid (DEF) Supply Pump has many functions. It's primary purpose is to draw fluid from the tank and build adequate system pressure for dosing into the exhaust. The Powertrain Control Module (PCM) provides the 12 Volt supply and ground to the pump. The PCM provides a Pulse Width Modulated (PWM) signal to the DEF Supply Pump to control the speed and output of the pump. The DEF Supply Module has an internal temperature sensor which reports the internal temperature of the DEF Supply Module to the PCM.