Theory Of Operation

The Diesel Exhaust Fluid (DEF) Dosing Control Unit is used to control the operation and monitoring of the Diesel Exhaust Fluid system. The DEF Dosing Control Unit is the central control for the aftertreatment diesel exhaust fluid dosing system, and handles the tank level sensing, tank temperature sensing, line heating, and tank heating. The DEF Dosing Control Unit shares information with the Powertrain Control Module (PCM) over the J1939 Data Link. The DEF Dosing Control Unit will illuminate the MIL light via the PCM after the diagnostics runs and fails for two consecutive trips. The DEF Dosing Control Unit will turn off the MIL light via the PCM when the monitor runs and passes in three consecutive key cycles.