For information only-My cruise control worked only when it wanted to-I looked for a bad ground or the switch on steering wheel- I replaced the 4 bulbs in 3rd brake light and YAHOO I got cruise all the time now- Try it you will be amazed

 

Pretty much ancient news. All 4 of the bulbs must work for the resistance to be right , LEDs must have "OBD2" resistors.
The computer uses the resistance of the third stop lamp to determine if it should turn the Cruise control on or off. Like when you are driving and step on the brake to turn it off.
In addition, the cruise control won't activate unless the brake pedal has been depressed. That is only possible with a standard trans that can be started in neutral.