Subsequently when I spoke to two different reps at FCA regarding the case they seemed to be reading from a script. The wording was "It is working as designed. If you are not satisfied with the performance you can file a complaint with FCA, but it is not a warranty issue."
I think I will give up and just buy the P3....
There is a way to create an argument against "operating as designed".
Our owners' manual has verbiage that states the ITBM has been designed and verified with electric trailer brakes.
It also tells us how to set the gain value. "Slide the manual brake control lever to the left to activate power to the trailer’s electric brakes independent of the tow vehicle’s brakes. If the manual brake control lever is activated while the brake is also applied, the greater of the two inputs determines the power sent to the trailer brakes." No mention of vehicle speed dependence.
Then they talk about gain, "The GAIN setting is used to set the trailer brake control for the specific towing condition and should be changed as towing conditions change. Changes to towing conditions include trailer load, vehicle load, road conditions and weather." So they do understand heavier trailers will need a higher gain setting. Now you are getting into the core of the issue and this clearly establishes the first data point that the ITBM does not work as intended or documented.
Next is the how to procedure to set gain. You are told to set the gain at speeds of 20 to 25 MPH, well below the 30 MPH threshold that limits the ITBM's output to 70%. Under this published process, it is impossible to properly set the gain. The second data point that boldly demonstrates there is an issue with the ITBM.
If the current ITBM design goes unchanged for MY17, a whole new round of complains will fire up as 2017 HDs are delivered.