Grade braking/engine braking

[larboc1]

I've got a 2012 silverado and a 2013, both unlocked with HPT and I'm trying to figure out how to get the engine braking on the suburban to work as aggressively as the silverado. When manually selecting a lower gear down a grade, the silverado will wait a few seconds after making the shift, then enter DFCO, then exit DOD mode if in it, then phase the cam to maximize negative torque. It works quite well.
The suburban however only goes to DFCO when I try it, not phasing the cam makes for a much less effective braking. ONCE when going down a long grade, the suburban went into it's "grade braking on" mode as displayed on the dash, and automagically downshifted and phased the cams to apply engine braking. Of course I wasn't logging to see what it did, and can't get it to do it again.

I've looked around both calibrations, and I don't see anything specific to any kind of braking strategy, nothing beyond dfco, so I assume this means I'm either blind or it's done in a more complex way. I also don't see any difference in cam positioning between the two.
Any thoughts? Both .hpt's attached
2013suburbanstock.hpt
totostock2.hpt

[blindsquirrel]

Since these are the only differences between those two files...

screenshot.24-11-2022 22.10.16.png

...I'd have to say that the grade braking feature is either in a part of the engine/trans calibration that isn't accessible in the editor, or, it's located in some other module other than ECM/TCM (like BCM, probably).

[SiriusC1024]

This is how the driver engages grade braking:

https://static.nhtsa.gov/odi/tsbs/20...hift%20Mode%29.