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.
The Tow/Haul Mode indicator bulb on the instrument cluster is supplied 12 volts and ground by the instrument cluster module. When the Tow/Haul mode is selected, the body control module will send a request on the serial data communication line to the instrument cluster module to turn ON the Tow/Haul indicator. Pressing and releasing the Tow/Haul Switch again will turn OFF the indicator and return the transmission to normal shifting.