I had the same problem with my 01 Ultra...It was the speed sensor. Taking it out and wiping it off will be a very temporary fix....I did that twice..the first time, I got about 50 miles before it started to fail..the second time, 20 miles..Replacement is the answer.
Cleaning it involved a few minutes..one allen screw..If cleaning it gets it all working, you'll know you found the problem. Replace it..I think the dealer charged me about $50...can't remember exactly.
