I've been dealing with a brake issue since I bought my first Ranger this spring. It's a 2000 4.0L 4x4. From talking to smarter people than me, I'm thinking that it's a bad proportioning valve.

Symptoms: sometimes when braking, the brakes will lock up just before a stop. It is intermittent, but usually only happens just before stopping. It's worse on wet pavement and with slightly harder but not extreme braking situations. ABS light is not on. I've mostly dealt by braking long and slow, but having to stop abruptly when stoplights change is pretty nerve racking. It feels like the rear brakes are the ones locking up, not the front, but I haven't been able to have someone check when it's acting up.

What I've done so far: checked the drums, pads and rotors myself and everything seemed fine. had a pro do an inspection, who said the drums were properly adjusted and the lines were nearly new, and they couldn't immediately see any problems. didn't suggest the proportioning valve to them because I wanted to see what they would come up with on their own, but when I followed up with them they said they didn't even check it. They said that replacing the prop valve would just be taking a stab in the dark and may not solve the problem.

I hear it's rare for a prop valve to go bad, but the symptoms I've seen online line up exactly with what I've been experiencing.

Any thoughts? am I on the right track? I've never messed with brake lines before, so I'd want a pro to replace the prop valve is that's what the problem is. how much of an ordeal is that? Is this a simple or complex fix, or even the right one?

appreciate everyone's suggestions.

 

Welcome to the forum

First look at your Master Cylinder and see if there are 1 or 2 brake lines coming out.

If 1 brake line then it will run to the proportioning valve next to Master
If 2 lines then the proportioning valve is part of the Master

It very well could be the front brakes are not getting the 70% they should be for a pickup truck(70/30 proportioning, cars are 60/40)
Rear brakes will always lock up if front brakes are not working as they should on any vehicle, just more noticeable on a pickup truck
So it may not be a rear brake issue, it may be front brakes are not working as they should.


All Ranger's had rear ABS since around 1990
There was an option for 4 wheel ABS after 1995

Your ABS light is not on but does it come on when you turn on the key, the Bulb Test?

The rear ABS doesn't have wheel sensors, just the one differential sensor, so it really can't tell if one wheel locks up, and this sensor is also shared with speedometer in 2000, I assume speedometer is working OK?
So the Rear ABS system doesn't really have a comparison between speed and rear axle rotation because it just has the one sensor for both, it will activate if there is a sudden drop in speed/rotation, but with an OPEN differential one wheel could lock up and differential would still be rotating so no ABS reaction

Thread here on some similar issues: https://www.ranger-forums.com/genera...ing-up-118928/