1986 Buick Electra Cruise control not turning on

It can be several things. First check your fuses to see if one is blown. Then check to see if the cruise unit gets power. Check your brake light switch to see if it is sending ppower to turnt eh cruise off and lastly check the relay. It may be under the dash or out under th hood by the unit. Also if there is a vacuum line going to it make sure that isn't leaking vacuum.