If your cruise control quits check to see if both brake lights are working.After checking the fuse,wiring,switches ect. it turned out to be simply the brake light bulbs.New bulbs----cruise fixed. Thanks Brian Leppin for the info.

Dave

There is a reason for this. The people who designed the cruise control did not want the cruise control to work if there was no input from the brake system to shut the cruise control off when stopping. The cruise control imparts a very small voltage to the brake light circuit. A very small amount of current flows (this is refered to as a supervised circuit) if the circuit is connected. A failure of the bulb failure sensor can have the same effect as having both stop lamps burnt out.

if the bulb failure senesor light stays on will that cause the cruise control to not work that well? mine works ok on flat, but any kind of grade and it doesn't hold speedat all.

You have a mechanical problem. Either linkage adjustment, leaking vacuum servo, bad vacuum pump, but most likely a leaking vacuum hose (split end).