Medium and Heavy Trucks
Have Truck Repair Questions? Ask an Expert
So this unit does have what they call a "Body Controller" that most cab accessories are controller through. All the switches you are experiencing issues with would be controlled through this controller but it is all ground signals that it communicates with. I would recommend reviewing the following link of where to find the wiring manual for your unit. Service and inspect all ground connections to and from your cab and the plugs in and out of the controller. If all else does not solve the issues then the controller may need to be replaced. If your not comfortable with purchasing this controller outright then I would recommend booking into a local Navistar dealer to confirm it is the controller. Sometimes with wiring issues like this its best to air on the side of caution in order for the repair costs to be controlled.
Best Regards, Nick!