Quote Originally Posted by Alvin
No, I was trying to figure out how the Avalanche gets the tow/haul mode signla but I think its happening thru can network.
You would be correct. The tow haul mode switch is a wired input to the BCM which then communicates the tow/haul command on the class 2 low data network to the TCM, therefore it is not hard wired into the TCM.

-From the service manual-

Circuit Description
Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to zero volts. This signals the transmission control module (TCM) to extend the length of time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.




Jay