Before spending big money or effort to solve cruise control problem, you can check the cruise control module connector first. You might only need to resolder couple of pin connectors and you are all set.  

 

Before this repair, my cuise control would be engaging sometimes when I switched it on, but it would quit for no reason after a while. Sometimes it was just refusing to work for me.  There would be times that I set it at 60 mph and it worked at 55 mph.  Looks like some connectors are loosing.

 

After re-heating the two brownish points, my cruise control works like new! One bad solder point is for 'vehicle speed input', the other is a ground point. This explained that the computer would get a wrong speed information and trigger a wrong control.

 

 

 

 

 

 

 

 

 

The two culprits are right here -- the brownish solder points:

 

    

 

 

 

After re-soldering: