K 1500 Truck 4WD V8-4.8L VIN V (2003)
Tow/Haul Switch: Testing and Inspection
4L60/4L60-E/4L65-E Transmission
Tow/Haul Switch/Indicator Always On or Inoperative
Tow/Haul Switch/Indicator Always On or Inoperative
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 Powertrain Control
Module (PCM) 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.
Diagnostic Aids
If the electrical circuit tests are OK and the tow/haul shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents
tow/haul operation.
