so i have an 01 2500 cummins and when i turn my lights on my cruise wont work. also my turn signal blinks really fast when the lights are on but not when they are off. its really weird any ideas?

 

That IS weird..... The lights and cruise control don't share anything in the electrical system that I am aware of..... The buttons on the steering wheel just modify a signal going back to the PCM, and the PCM does it's magic with the servo from there.

As for the lights, sounds like you have a bulb burned out, and the filament is shorting across to the second filament in the bulb.

Going to move this to the 2nd Gen Ram section for ya. Welcome to DF!

 

Check ground G100 which is somewhere on the left front inside fender. For reasons only known to the Chrysler engineers the speed control servo and the rear lighting share the same ground.

 

Does your trailer electrical connector work properly?