I just bought a 2001 dodge 3500 4x4 diesel. The cruise control has not worked since purchase. I bought a new switch that mounts on the steering wheel and that did not fix the problem. I can not find any fuses under the hood or inside the truck. Does anyone have any idea's on what could be causing my problem, or where I should look next. Thanks, Nathan

 

Is the air bag light on too? Does the horn work? If so it is probably the clock spring under the steeringwheel.
You might want to also inspect the vacuum line to the servo. Make sure you have strong vacuum on the hose while the engine is running.

 

I would post in the cummins section if I were you, you will be able to get more answers.