Cruise Control
 

Sometimes when my cruise control is engaged and I hit a large bump in the road it will go off and I usually have to pull over and shut off the engine and restart to get it to work again. Yet other times when it goes off it may not come back on for days.

What mite this be and how do I check it out?

Do a search under "cruise control amp" or "cruise control amplifier" to help you decide if this is your problem. Lots of information on this subject.