I have a 2003 2500HD 6.0L. The tow Haul isnt working and the light doesnt even come on in the dash board. Does anyone know if there is a fuse for this? I've looked in both fuse blocks and I haven't found one. Or can anyone tell me how it hooks up so I can check for loose or unhooked wires.......Thanks.

What trans?

What trans?


To be honest, I'm not sure. But I can tell you that it's not an Allison. Just a 4 speed automatic

The tow/haul switch is a momentary switch input to the BCM, which then the BCM sends a class 2 message to the pcm to go into or out of tow/haul mode. So without having a scan tool it would be hard to tell if the bcm is seeing an input from the switch. You could try to locate at the base of the column where the wires for the switch come out and test for momentary continuity when you push the button.