Some D owners report that their cruise control does not operate above a certain speed, but that it works fine below that speed.  The Allison transmission can be programmed for many different parameters, and one of these parameters that can be programmed is the maximum cruise control speed.  To reset your cruise control to a new maximum speed, follow this procedure:
  1. Be sure cruise control is in the "off" position, crank up and get up to highway speed.
  2. When at the speed desired, turn cruise control button on and off ten times.
  3. On the 11th time, leave the switch on, depress the set button and hold the "resume" switch to the left until the accelerator begins to pull away from your foot, then release both "set" and "resume" buttons.
  4. Tap your brakes to disengage the cruise control, then activate the "resume" button.

The cruise control should then set at the speed you were travelling as well as all points below that speed.