I have a 93 F150 with an auto trans, 351W, 4x4, just turned 120,000mi. My cruise control recently stopped working completely but that was fixed with a new switch on the brake line (the recall had already been performed but that newer switch had failed). Once I replaced that switch the cruise worked flawlessly again for around 1,000mi but then it started cutting out.
I'll set cruise and it'll hold for maybe 10mi and then the cruise will shut off and not come back on. Sometimes when I restart the truck later it will start working again, sometimes not. Any time that it comes back it only will last for a short while before cutting back off.
Horn works, tail lights work, fuses are all good. Could my cruise module be giving out?

 

There are two Speed Control deactivate circuits. One is the Brake Pressure switch located on the brake line, the other is the Brake On-Off switch (BOO). A faulty switch can momentarily activate the brake circuit which in turn shuts off the Speed Control. A low brake pedal can trigger it too. One other frequently overlooked cause is a bad bulb. A hanging filament inside the bulb can momentarily touch the brake light filament (assumes the parking lights are on) due to vibration. This applies 12V to the BOO circuit.

For reference:


There is also the clutch jumper for automatic equipped trucks. Check it too.

 

Ok I think I can eliminate the bad bulb theory because it does it even when the lights are off.
If the BOO was bad would it cause faulty brake lights? I have seen where people replaced that switch because their brake lights wouldn't come on or worked intermittently, but mine work fine. The BOO is on the brake pedal assembly, correct?
Where would I find the trans clutch jumper?

 

If the BOO switch is just barely off the contact road vibration could trigger it.

Clutch Pedal Position Switch Jumper Location:

 

Would that also prevent the cruise from re-engaging? I know the brake sensor cuts off the cruise but wouldn't you then be able to turn it back on?
When mine cuts off I can't turn it back on, it randomly starts working later on. The only constant I can find in the process is that it never comes back on while I'm still driving, it's always after the truck has been off and parked for a while.
If the BOO stayed in contact making it think that the brakes were on, wouldn't my brake lights stay on also?

 

I did not read your original statement to mean the Speed Control would not engage again. I read that it would drop out, then you had to set the speed again. Sorry.

It could be the speed control module or the switches that activate it.

Some items to check related to the switches and other bits of info:


If the switch resistance is the same for when the system is working and not working then the module is most likely bad.