E78 TOW/HAUL function without BCM?

[sgtbilko]

If I missed the answer in my search, please just help me find it.

I have a 2016 L96/6L90e with the E78 ECM and no BCM (swapped into a Squarebody truck).

Anyone know how to wire up the TOW/HAUL function without the BCM?
Surely someone has done this.
Assuming it's either a momentary ground or a specific resistance in a 12 volt supply to a pin on either the ECM or TCM.

[blindsquirrel]

It's a Class2 serial (or CANBUS) message. The little box in the video below enables those BCM functions along with a bunch of other useful stuff.

https://www.youtube.com/watch?v=vXnBMG-axm4

[sgtbilko]

Well if all else fails, perhaps I can figure out how to send that "message". Arduino maybe...any idea where to find a copy?
Seems the cruise control and Tap-shift systems run through the BCM as well, but they have alternative option to communicate via resistor trees. I don't understand why Tow/Haul is different. Also wonder if the HPT developers might would be able to help by enabling something in the software?