Reductant Pump Assembly - All Others
The reluctant pump assembly contains a diaphragm pressure pump, a pressure sensor, a purge valve, an outlet filter, and an internal heating element.
The reluctant pressure sensor provides feedback to the PCM, which regulates system pressure by controlling pump speed using pulse width modulation (PWM).
When the PCM requests reluctant injection, the reluctant injector opens and the pump operates, filling the reluctant pressure line and injector and purging air from the system. When all air is purged, the injector closes and the pump builds pressure to 500 kPa (73 psi). The system is then primed and the injector provides diesel exhaust fluid (DEF) to the selective catalytic reduction (SCR) catalyst as commanded by the PCM.
When the vehicle is shut down, the PCM closes the injector and actuates the reluctant purge valve, causing the pump to reverse flow and bleed down pressure on the reluctant pressure line. The PCM then opens the injector to allow gas to enter the reluctant pressure line, which in turn allows the pump to purge all remaining DEF from the system and return it to the reluctant tank. The PCM closes the injector and returns the purge valve to the forward position.
The PCM commands the glow plug control module (GPCM) to provide voltage to the reluctant pump assembly internal heating element when the reluctant temperature approaches -11°C (12°F).