I had one heck of a time with the CC on my 2000 after changing the throttle cables due to stiff action. This diagnostic procedure helped alot. and was provided by a member of this fourm, what a great place with great people.
This procedure must be done exactly as follows while you monitor the SET light on the instrument cluster:
1: With the ignition switch OFF,switch on the cruise control. Press and hold the cruise control switch to the SET position and switch on the ignition switch(LIGHT)
2: Release the SET button (LIGHT GOES OFF),move the switch to the RESET position(LIGHT)
3: Release the button(LIGHT OFF)switch OFF the cruise control switch(LIGHT)
4: Switch the cruise contol back on(LIGHT OFF)
5: Rotate the throttle against the throttle stop(LIGHT ON),Release the Throttle(LIGHT OFF)
6: Pull the clutch lever(LIGHT), release the clutch lever(LIGHT OFF)
Note: The throttle and the clutch switches are on the same input to the cruise conrol module,so if one of these is stuck in the ON position, the other will show no action. So if you get no indication for the throttle switch, do not assume it is at fault,it could be a stuck clutch switch.
7: Pull the front brake lever(LIGHT), release the lever(LIGHT OFF)
8: Push the foot brake pedal(LIGHT ON), hold for 5 seconds(LIGHT OFF),release the foot brke pedal(LIGHT ON)
Note: both brake switches are on the same input to the controller, so again if one is stuck on, neither will show on the test.
9: Rotate the rear whee(LIGHT SHOULD GO OFF/ON)
10: Switch off the ignition.
Good luck in getting this sorted out. hope this helps there are quite a few items that will stop the CC operation.