Brake pedal locking up.

[ff2024]

1999 Ranger 4.0L 4x4 Vin X

Ok, when coming to a slow stop, downhill stop or a turning stop (especially the turning stop), the brake pedal locks up and gets too hard to push and the brakes don't engage, I just keep rolling. Then it will release and basically do it again. This happens 98% of the time. I checked the calipers (I can push them in with ease) and the pads and rotors are new and are smooth as could be. Now I'm lost because I don't know what to check next. Possibly the Master Cylinder? Please help. I have totally had it with nothing seems to stay working on this truck and I baby the hell out of it. Did I get a lemon or is it just Ford engineering?

 

[MAKG]

I suppose it could be the master cylinder, but the first place I'd look is the power brake booster. Any chance this problem is accompanied by a hissing noise in the cab? Also check engine vacuum. Does the engine bog during turns (it's a sign of a problematic PS pump)?

Hydraulic problems make the pedal soft, not hard. If it's the master cylinder, it's binding.

 

[ff2024]

There is a small hissing noise in the cab when it locks up. I do have the check engine light with the code for a vacuum leak but i know that it's the hole in my gas tank filler tube. So possibly the Power Brake Booster?

 

[ff2024]

No the engine doesn't bog at all during turns.

 

[michowski]

Sounds like the power brake booster. That uses vacuum to make it easy for someone to push the pedal down with ease. I would first open the hood and check that hose that goes to the booster. Make sure it doesnt have a hole in it or something of that sort.

 

[MAKG]

If you get hissing with the brakes on, your power brake booster is bad whether or not it is the problem at hand. It's not just a line fallen off. I think it *is* the problem at hand.

FYI, that's not a lockup. A lockup means you put the brakes on and can't get the off again. This is just hard pedal.

 

[ff2024]

Now here is what I encountered yesterday. I have absolutely no problem SLOWING DOWN, the pedal only gets hard when I try to come to a complete stop. The pedal only seems to get hard when I try to stop? Now if the Power Brake Booster were bad, how would that affect me slowing down?

Thanks...you guys are the best!

 

[Mutant Pony]

If the booster is bad the brakes will still work fine, you just have to push a lot harder.

 

[pimtool]

Do 99 rangers have front ABS? When the wheel speed sensor/wheel bearing goes, doesnt it feel like the pedal is pushing back when you are trying to stop at slow speeds? 3-5 mph

 

[Wicked_Sludge]

heres what it sounds like to me:

your brake booster is bad, causing a vacuum leak. the booster is still functioning well enough to boost your brakes under most conditions. while braking to a stop, the engine is bogging due to the vacuum leak, which causes it to loose vacuum, thus no longer supplying the booster and making your brake pedal hard.

of coarse all this goes out the door if your RPM's arent dropping when the problem occurs.

either way, if its hissing, you have a bad booster.

and a code for a vacuum leak and a code for evaporative emission leak (such as your fuel tank filler tube) are two different animals.

 

[ff2024]

Ok 2 days ago I pulled the 10A fuse for the ABS and haven't had any problems since. It brakes perfect. I'm guessing it's possibly the ABS speed sensor since that fuse controlled the speedometer as well. Does this sound correct? Or is it the whole ABS unit?

Thanks

 

[MAKG]

If your brakes are hissing, your booster is bad.

Guessing at ABS diagnosis is equivalent to throwing $100 bills in the campfire.

 

[ff2024]

Ok replaced the Power Brake Booster...still have the same problem. Now this all started when I put slotted rotors on the front. Would this in any way affect the ABS speed sensors to cause my problem? Just a thought.

Thanks

 

[Sasquatch_Ryda]

Did you knock a tone ring off? Or maybe hit the speed sensor?

 

[pimtool]

Have a shop put a scan tool on it and they can tell you if one of your speed sensors are reading incorrectly. It will only take a short test drive to find out.