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 0 volts. This signals the transmission control module (TCM) to extend the length of time between upshifts. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.
Diagnostic Aids
^ The tow/haul switch is hard wired to the BCM where it is then broadcasted on Class 2 Serial Data link to the TCM.
^ Observe tow/haul status on the scan tool to see if the status changes.
^ Inspect the wiring for poor electrical connections at the BCM. Inspect for the following conditions:
^ A bent terminal
^ A backed out terminal
^ A damaged terminal
^ Poor terminal tension
^ A chafed wire
^ A broken wire inside the insulation
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests for a faulty tow/haul switch.
3. This step tests for voltage input from the BCM to the tow/haul switch.
6. This step tests for ground integrity.
