You would have to perform test to find out what is causing the problem.
Brake switch has 2 circuits, one for the brake lights and the other for the cruise control. When brake pedal is not depressed, the the cruise control circuit must have continuity whereas the brake circuit should not have any. When brake pedal is depressed, the situation reverses.
Check the brake switch to pedal clearance adjustment, excessive clearance would cause the cruise control circuit to be open.
Thursday, October 28th, 2010 AT 2:00 PM