Circuit/System Description
WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban 3500 HD, and 2018 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
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 from 12 volts to zero volts. The BCM then sends a signal out on the serial data line to the transmission control module (TCM) to increase transmission line pressure and extend the time between upshifts. Selecting the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.