There have been a couple posts indicating some Harley material on this issue. The way I read it, was gear conversions not working.
Upgrading to helical 5this Not Retrofitable
–Results of upgrading to the helical 5thgear
•Vehicle Speed slower than indicated by speedometer
•The 6thgear light may not function correctly
•No plan for new calibration
Any advise before having the dealer solve this problem?
I believe you will find that the information posted does not apply to a stock bike, and was just published to the dealers so they would know that trying to update an older trans to the new helical gear set could create those problems. Even Harley-Davidson couldn't get away with shipping those kinds of known defects and expecting customers to accept them. Wait a minute, I probably should take that comment back. They've already proven many times that they think they can get away with shipping crap.
Anyway, assuming you haven't modified anything, the light should work and your speedometer shouldn't be any less accurate than any other Harley. Just tell the dealership what it's doing and that you want it fixed. If they jerk you around, call the Customer Service number for Harley. In other words, handle it like all the other defects.
Jerry