I have a rather strange problem with my 2001 S89 T6. While I am climbing a grade with the cruise control engaged at 60-70 mph the cruise control will not disengage with normal pressure on the brake pedel. It takes an abnormal amount of force on the brake pedel to disengage the cruise control. When I am cruising along on the level a simple tap on the brake pedel will shut off the cruise control.

Does anybody have any ideas or suggestions. The check engine light is not on and the dealer has no suggestions.