The cruise control on my olds 88 quit working. What is likely wrong?

What is certainly wrong is that if you don't even know enough to mention the year of the car, and exactly what it is or isn't doing, there is nothing we can tell you that will help you fix it yourself.

See if the owner's manual mentions how to put the cruise control computer into diagnostic mode by flipping the cruise control switch or button or ignition switch a certain way. Even my 1986 Toyota can blink diagnostic codes for cruise control.

Car makers want to make sure that the cruise control shuts off if the brakes are applied, so check anything brake related, like the brake lights, brake pedal switch, parking brake switch (you do use the parking brake, right? If not, the switch contacts may have crudded up), brake pressure switch, brake fluid level float switch. A few months ago, my cruise control wouldn't work because the brake fluid level was a bit low. I don't know if your cruise control is controlled by an electric motor, but older ones were powered by vacuum, so check for electrical connections or vacuum hoses going to a device that attaches to the throttle cable.

The best sources of information are factory and Mitchell manuals at the library or forums that specialize in GM vehicles. Chilton's, Haynes, and AutoZone.com may have the info, but they're usually pretty bad for anything computer related, and I haven't seen a correct wiring diagram in them for any vehicle built in the past 20 years.

Thank you so much larrymoencurly. This gives me some things to check out. I appreciate it!