I have a 99 softail. speedo/odometer problems.....same as yours so I worked on the speedo yesterday and today...all the wires checked out so I narrowed it down to speedo itself or the speed sensor. shop manual uses a speedometer tester part number HD-41354. I figured this would be nice to diagnose my problem. called the dealer to see if they had this test set, they told me I had to bring my bike in because they don't work on parts off the bike. I asked if I brought in a wheel would they mount and balance a tire and they said sure? WTF? Thanks for nothing!
anyway now I think it may be the voltage regulator. had me puzzled. didn't realize there was a diagnostic mode on the speedo which showed the fault code of d08 which means over voltage. speedo and odometer work fine when sitting idle but as I accelerate the speedo goes to 0 and the odometer blanks out. I had a multi meter on the battery while the bike was off....12 volts. at idle, 14 volts and as I increase the throttle the voltage jumps up to 17 volts and thats when the speedo fails. should stay at 14 correct? I am thinking voltage regulator. the dealer has one for $122, I went outside and checked Drag Specialties on my phone...$53.99. went back inside and told the parts guys no thanks I found it for cheaper.....he said I would still have to pay shipping..HAHA! did you ever figure out the problem? looking for some feedback before I pull the trigger on any new parts. thanks.