Ok to start with there are 2 switches involved in the operation of the cruise that are located over the clutch pedal and the brake pedal. So to start with lets bypass these 2. You need to make a short jumper wire to use for this. Unplug the harnesses from these 2 switches and jumper them each. Now drive the car and see if the cruise will kick in when you try to set it. Also be sure to try engaging it with the set button in the end of the stalk and also the accel slider on the side of the stalk.
WARNING: By bypassing the 2 switches at the pedals there is only one way to cut the cruise off if it engages and thats with the slider switch on the stalk!!!!