DEF Filling Instructions
DEF Filling InstructionsCustomers or dealers may have comments on adding fluid to the DEF tank. The capacity of the tank is 20•L (5.3•gal) and the trucks are shipped with 7.5•L (2•gal) from assembly. During PDI, it may be possible to add more than the approximate 13•L (3.5•gal) of remaining capacity. Most likely this is related to the filling procedure. Customers may also be able to fill the tank more than 20•L (5.3•gal).
DEF basically behaves like water and will freeze at -11°C (12°F) and will expand. This does not normally cause a problem if the DEF tank is not overfilled. Adding more than the 20•L (5.3•gal) usable capacity may not allow for DEF expansion when frozen.
To prevent damage from freezing, during PDI do not add more than the 13•L (3.5•gal) allowed during PDI. This should be done just before delivery to the customer.
Tip
To maximize driving range and to prevent over filling the tank, wait until the "Exhaust Fluid Range: 1000 miles (approximate) (1609 km)" message appears on the DIC. At this point, add up to 13 L (3.5 gal). Do not add more than 13 L (3.5 gal) of DEF. When using the CC&A DEF 3.78 L (1 Gal) 88862659 (88862660 (Canada) or 9.46 L (2.5 Gal) 88863523 (88863524 (Canada) fluid with the nozzle properly installed, when fluid reaches the top of the fill pipe, stop filling. Instructions are provided on the bottle for proper nozzle installation. If another source of DEF is being used, when fluid initially reaches the top of the fill pipe, stop filling and do not force additional fluid into the tank.
Frozen Tank Status
Condition
In operating temperatures of 15°F (-9°C) or less, customers may comment on an "Exhaust Fluid Range" message displaying on the DIC even though the DEF fluid has been filled.
Cause
When the DEF is frozen, the level sensor cannot determine the fluid level in the tank. If this occurs the logic of the PCM will assume a default fluid level. The logic will use the calculated range based on DEF dosing history and the assumed fluid level.
If there is a high learned dosing rate and the fluid has not thawed to where the pins of the level sensor can function, there is a possibility the "Exhaust Fluid Range" message can set with the range from approximately 1609 km (1000 mi) to less than 482 km (300 mi), even though the tank is known to have fluid or be full.
Correction
This is an operating characteristic of the system. However to increase or eliminate the range message, once the range drops below 482 km (300 mi), the DEF tank should be refilled. This should allow refill detection to occur and turn off the range indicator. The operator must be sure not to overfill the DEF tank using the instructions provided in this bulletin or in the owner's manual.
When in frozen tank status, refill detections are not allowed until the warning strategy reaches the point at which the distance remaining is less than 482 km (300 mi). The refill detection is dependent on the DEF thawing enough that the level sensor pins can be read. A fully frozen tank can take almost an hour to detect a refill, after the vehicle is started.
This condition should not be confused with the situation described in PIP4864: "Low Or Speed Limited Diesel Exhaust Fluid Message (DEF) Will Not Reset". However it can be very difficult to differentiate the PIP4864 and the Frozen Tank Status. If there is any question about which condition has occurred, and there is an updated calibration available through TIS, follow the instructions in PIP4864.
Tank Fill Level Status and DEF Range Remaining
The DEF system only provides range information from approximately 1609 km (1000 mi) and lower. If there is not any warning, the range is more than 1609 km (1000 mi) at the current usage rate. The range can and will change based on the environmental conditions and vehicle use.
The Tech 2 does show information on tank capacity, however it only covers approximately 6.32 L (1.67 gal) of volume and is used to calculate the remaining range starting with the 1609 km (1000 mi) remaining status using 3 pins to detect the level status.
Using the Tech 2 in the ECM, Data Display function, the following information is available:
Distance remaining calculation has 3 phases:
- Phase 1 - Fixed consumption mode
- Active only when vehicle is first flashed.
- Distance remaining is calculated based on the volume estimated in the tank and a calibrated consumption rate.
- The system transitions to Phase 2 after a calibrated distance and minimum dosed quantity of DEF.
- Phase 2 - Dynamic consumption mode
- Distance remaining based on volume of mass in tank and rolling average of urea consumption using 5 blocks of data.
- At transition from Phase 1, the 5 blocks are populated with average consumption from Phase 1.
- The moving average of consumption rate is then updated at calibrated intervals (currently 320 km (200 mi) for Silverado/Sierra models and 400 km (250 mi) for Express/Savana vans.
- Phase 3 - Level below 2nd pin
- Dynamic consumption mode (same as Phase 2)
- Separate mileage interval can be applied once in Phase 3.
- Silverado/Sierra = 160 km (100 mi)
- Express/Savana = 200 km (125 mi)
Refill Detection Chart
The following chart shows the parameters related to how the DEF system recognizes a fluid fill.
If the truck is parked on an incline, it is possible a stationary refill detection may require more than 3.7 L (1 gal) to be recognized. Driving refill detection should still function properly.
If the tank is frozen, the detection process can be delayed.
