Cruise control not engaging

DrewE described corrosion in the electrical and fuse connections at the master cylinder. I can confirm that. Last year my CC stopped working and it was suggested I check that fuse. Was I surprised to see the amount of corrosion present, no way an electrical signal was going to get through. With a small wire brush and electrical spray cleaner I was back up and running in no time. Best of luck.

The "Clock Spring" also has part in the circuit. It can be found by pulling the steering wheel.

This happened on my Chrysler automobile, but it might apply to a motorhome. The "check engine" light came on for short time then went out. After that, the cruise control would not engage.

Local mechanic found a brake sensor in the anti-skid system that was bad. Replacing the sensor fixed both the cruise control and the anti-skid system.

The Fords use a brake fluid pressure switch mounted to the master cylinder assembly to disengage the cruise control, and these are known to sometimes corrode and malfunction due to fluid seepage/leakage internally. There was (or is) a very broad recall on the issue, wherein a fuse was added to keep the switch from starting a fire if it shorts out. At any rate, a failure of that switch is a common cause of the cruise control not working.

Start behind your rig.. Are the brake lights on?
Now there are a whole lot of possible problems but
when it happened to me (under warranty thank heaven)
it was a defective brake light switch. and thus the brake lights were on.

Why check this first? Only tools needed are your eyes. ANd perhaps a partner
Then you can move on to the more expensive tests.

NOTE also. you may have a partner hit the brakes and make sure the brake lights come on when they do so.. for if they do not THAT will also prevent it from working.

If Brake lights on : Defective brake light switch
If not: Burned out bulbs. Blown fuse. Wiring issue IE bad ground.

But the behaviour of the brake lights is the first test.

^^^ This. If not that check the brake switch itself. Also check for a blown fuse. It should be something simple.

Make sure the brake pedal is all the way up. I had the same problem, turned out the rv was low on brake fluid.