97 E350 R.V. ABS Light comes on sometimes
 

I have a 27 foot 1997 R.V. on an E350 chassis and when we take it out on a trip the ABS light will come on at some point and stay on for a while, most of the time it goes away. I am wondering what is the best way to proceed. I thought about buying a wheel sensor and just moving it from wheel to wheel until I find the bad one, but that seems like a lot of work, especially since I don't drive it very often and the brakes still work fine. If anyone has any suggestions I would appreciate the help.

Thanks,
Randy