T42 4L80 tow/haul switch

[DURAtotheMAX]

Just wondering...are there any 4L80 T42 OS's out there that have a discrete input for selecting the secondary shift schedule? (tow/haul, performance, whatever)

Or are they all setup for switching via CAN/serial data only?

Im building a Duramax/4L80 standalone setup, and it would be nice if there existed a TCM OS that didnt require the factory BCM to be wired up in order to turn tow/haul on and off.....

Thanks
Ben

[DURAtotheMAX]

Bump...anyone know?

[joecar]

I think they do it over the CAN bus/lan, but you have to check the Service Manual wiring diagrams...

the vehicles that switched tow/haul directly typically used a PCM (i.e. not ECM/TCM) back in the day.