1994 ranger cruise control issue

[gnorton52]

I have a 1994 ranger 4.0L with factory cruise control. Recently started disengaging when driving over a bumpy road. Anyone else have that issue? And what did you do to fix it?
Thanks

 

[RonD]

Welcome to the forum

Does the cruise deactivate like you pressed brake pedal, and then you just hit the SET control again
Or does cruise turn OFF
Or does it just slow down and then speed up again

Could be loose clutch pedal or brake pedal switch, the brake pedal switch has TWO switches inside, one for brake light only, and the other is a "sensor"
Its sends 12v when pedal is up, and 0v when pedal is down the wire from this sensor passes thru the clutch pedal switch to the Cruise module
So if cruise module sees 0v(brake pedal down) it deactivates, or if it loses 12v(clutch pedal down) it deactivates
Generally its brake pedal if this is the problem, but could be either

And then there is the clockspring under steering wheel and the buttons, any loose connection may cause cruise to deactivate

There is also a Vacuum release valve in the cab where the brake push rod goes into the Booster, it releases the vacuum holding throttle open if brake pedal is depressed, a mechanical backup to electric shut off, this should just slow you down not deactivate the cruise, and you may hear that if radio was off, as an air hiss noise

But it does read like a loose something if it only happens when you hit a bump, unplug the wires on cruise module(on engine bay actuator) check for corrosion and plug back in
Do the same on brake switch and clutch switch

 

[RobbieD]

Or just don't drive on any bumpy roads.

Seriously, RonD covered it all. The only thing I can add, if none of the above check out, look at your pedals for excessive slop. The plastic bushings, when worn or simply gone, can cause your pedals to bounce enough to throw one of the cruise related switches.

 

[RonD]

+1 ^^^^

Try putting your foot under the brake pedal and holding it up when bumps are expected, see if it still disengages
Same for clutch pedal if brake pedal tests is OK