Diesel Exhaust Fluid Tank Module - If Equipped
| ITEM | DESCRIPTION |
|---|---|
| 1 | Diesel Exhaust Fluid (DEF) tank module |
| 2 | DEF line heater |
The Diesel Exhaust Fluid (DEF) tank module is located at the bottom of the DEF tank. The DEF tank module includes a DEF level and temperature sensor and a heater element to defrost the DEF in extreme cold climates.
The DEF level sensor is an ultrasonic device which sends the DEF level value to the Powertrain Control Module (PCM) via Pulse Width Modulation (PWM) signals. The Negative Temperature Coefficient (NTC) temperature sensor measures the temperature of the fluid in the DEF tank. Similar to the ultrasonic DEF level sensor, the temperature sensor transmits the initial temperature signal to an evaluation unit in the tank module. Then the signal is converted into a PWM signal and sent to the PCM for processing.
The heater element is a Positive Temperature Coefficient (PTC) heater, which provides safe operation to the system. A feature of this design is that the current drawn from the electrical power supply reduces as the temperature of the element increases. Under normal operation the maximum current is 6A. The heater element is designed to defrost the DEF in extreme cold climates.
The DEF tank module receives a 12V power supply from a DEF relay located in the Rear Junction Box (RJB). The PCM relay, located in the Engine Junction Box (EJB), provides the power supply and the control signal for the DEF relay. The PCM relay is controlled by the PCM.
The PCM controls the DEF injection pump which comprises 2 solenoid pumps within the DEF tank. The first pump supplies pressurized DEF to the DEF injector. The second pump purges DEF from the DEF line to prevent freezing in cold climates. Both pumps are controlled by a ground connection from the PCM.
The DEF line heater receives a power supply from the DEF heater control unit. The DEF line heater provides heating of the DEF as it passes from the DEF tank to the DEF injector in cold conditions. Operation of the DEF line heater is controlled by the PCM via the private Controller Area Network (CAN) bus.