My cruise control never works which sucks because I use it all the time. I have my check engine light on with no codes presented with the built code reader. No airbag light displayed. Haven't had the opportunity to disconnect the battery yet.

 

I drove my mountaineer for several years without cruise. No codes. However I then bought a more expensive reader capable of reading ABS codes on domestic vehicles. It showed a fault in a sensor on top of the master cylinder. The part only cost $12 and took 5 minutes to install. Basically it was the sensor that determines you've hit your brakes which shuts the cruise off. Because the sensor was bad it would never let it go into cruise control.