That was very helpful. Plenty of vacuum, can't be the issue. The LED performs every function you suggested including the increased blinking when throttle advanced. This Audiovox ccs-100 passes all tests. Except it does not engage and , when brake is applied the dash switch indicates it has turned itself off. I tried just cutting the purple wire to the brake light but the unit would not function, nothing, no dash green light, no red LED. Must be something in the tail light wiring???? I installed this cruise control almost 5 years ago and it works great. Used this cruise control every time I rode. When I rode for the first time this Spring it failed to function..... ??????? Thanks for the help.