Def Heaters

[sceptre]

I heard a rumour today that the DEF heaters are only heating in the first 30 mins the truck is running. Some guys at work have had problems with the DEF tanks freezing while travelling down the highway at 60mph in -20deg temps so just trying to get some details on the system operation.

 

Anybody have any info on this heating system?

[minibike132]

I don't have any experience with this system and since I'm out of the dealers I probably will never see it so I don't have anything intelligent to add to this. Here is what the service manual says about cold weather operation

 

 

Cold Weather Operation

As reductant will freeze at temperatures below 0°C (32°F), there are 3 reductant heaters. Reductant heater 1 is in the reductant reservoir, reductant heater 2 is in the supply line to the reductant injector, and reductant heater 3 is at the reductant pump. The ECM monitors the reductant temperature sensor located within the reservoir in order to determine if reductant temperature is below its freeze point. If the ECM determines that the reductant may be frozen, it signals the Glow Plug Control Module (GPCM) to energize the reductant heaters.

 

Reductant pump operation is disabled for a calibrated amount of time to allow the heaters time to thaw the frozen reductant. Once the thaw period expires, the ECM energizes the reductant pump to circulate warm reductant through the de-energized reductant purge valve and back to the reservoir. This is done to speed thawing. The ECM looks for an increase in the reductant temperature to verify that the reductant reservoir heater is working.

[ChevyTech77]

I heard a rumour today that the DEF heaters are only heating in the first 30 mins the truck is running. Some guys at work have had problems with the DEF tanks freezing while travelling down the highway at 60mph in -20deg temps so just trying to get some details on the system operation.

 

Anybody have any info on this heating system?

 

It shouldn't be turning off after 30 minutes. It should be turning on and off by temp of the def in the tank. -20d temps are gonna be hard to keep that stuff from freezing for sure. Have them take them in and get their concerns

documented though. There is a new calibration for that system out, that may help, also.