Sorry to bring back this post. But I FINALLY DID IT!!!!. I fixed my cruise control. There were two problems that was causing my cruise control to not engauge. First: The cruise control motor wasen't creating a vacum and would not hold the throthle open. Second: and probably the most comon problem with the 240sx's cruise control problem, is that the Brake pedal cancel switch goes bad. In order for cruise control to work properly it looks at several things: Vehicle speed, vacum, and brake cancel switch. If one of these components fail, you would not have cruise control.
I hope you guys can fix your cruise control problem, I know I did and I'm happy with my cruise control. :bigthumbu