I leave the dash switch on all the time. Should display an orange icon when on. Gently depress the button on the turn lever end above 30 MPH and you should see a green icon above the orange one and the cruise should set with foot off accelerator. If you depress the button fully or with force, the system will set then disengage all at once. If both lights come on and it still wont set, inspect the linkage from the servo to the throttle arm for having too much slack or being disconnected. If all ok, then check the vacuum hoses at the servo for being cracked, kinked or split.