2003 Express 3500 Tow/Haul Switch

I have a 2003 Chevy Express 3500, 6.0L gas with 180k. Recently the tow/haul mode began engaging and disengaging by itself. This occurs at all speeds and rpm ranges. The switch has been ruled out because the behavior occurs even with the switch removed. There are no error codes. We have removed as much of the dash as possible to trace the wires for a short and have check the wiring at the tranny. Any help on resolving this or info on simply disabling the tow haul function would be appreciated.