Circuit Description
WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet Silverado. 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 is selected, the tow/haul switch input signal to the Body Control Module (BCM) is momentarily toggled to zero volts. The BCM sends a serial data message to the Powertrain Control Module (PCM) and Instrument Panel Controller (IPC). The PCM extends the length of time between upshifts, increases transmission line pressure and the IPC illuminates the tow/haul indicator lamp. Cycling the tow/haul switch again disables the tow/haul mode and returns the transmission to a normal shift pattern.