I have a problem with the brakes on my 2001 F-250 SD, CC, SB. It has 4 wheel ABS. I have stock size LT265/75R-16 tires.

Under moderately hard to very hard braking the brake system will often hydraulically lock. The braking effectiveness is reduced to about 70%-80% of normal. The system feels as if the antilock brake system is activated without any pedal pulsing. Extreme force on the pedal does not increase braking force or produce ABS pedal pulsing. This occurs with cold or warm brakes.

Sometimes the brakes function normally under the same moderately hard to very hard braking conditions. When the brakes function well, I get very strong, effective braking without any hydraulic lock.

When the hydraulic lock condition occurs if I momentarily let off the brake pedal and press it hard again, usually the brakes function correctly.

The truck does not pull to the side when braking under either condition.

When I test the brakes on a grass field, the ABS system works quite well. The ABS hydraulically limits pedal travel just like the braking described above. It also pulses the brakes, which is what I would expect. The truck stops very well.

The ABS light has not illuminated during any of these events.

When I disconnect the ABS fuse, the truck brakes straight without any pull to the side under skid and non-skid conditions. With the ABS off, both rear wheels skid evenly under moderately hard braking on dry pavement. The rear wheels start skidding at about the same level of braking that will hydraulically lock the brake pedal when the ABS system is not disabled.

Here is what I have recently done to the brakes…

Install ART front rotors and pads.
Install new front caliper slide pins. I greased them with brake grease.
The rear caliper slide pins were re-greased. They were in good condition.
The rear brake rotors and pads are in good condition.
I bled each caliper.

The only time the ABS light is on is when the ABS fuse is out.

I suspect the ABS control unit is acting flaky for some reason. Any thoughts on how to resolve this?

 

I'm not sure what you mean by "hydraulic lock", but I can tell you that when my ABS activates on dry pavement I do not get the ABS "pulsing" feeling in the brake pedal. The pedal goes down a bit and there is a slight hum or vibration. On slick surfaces I get more or a pulsing feeling.

I've never looked to see what the ABS light was doing at that point, I was always kind of busy trying to drive the truck.

 

By hydraulic lock, I mean the brake pedal is hydraulically stopped from going down any further, even with extreme pedal force. It feels like the brake pedal has hit a hard mechanical stop, even though there is nothing physically preventing further pedal travel except the hydraulic back pressure. When the hydraulic lock occurs, the braking force will not increase with increased pedal force, even extreme pedal force.

 

When you did your brakes did you change your brake fluid also?I had that sensation also.I changed all the rotors/pads/fluid/lines.I dont have that issue anymore.Personally the rotor/pads were not all that bad.I have come to think my problem was the fluid from the start................2cents

 

The brake fluid was not changed.

The brake fluid may be causing or contributing to the problem.

 

It might be.When I did mine the fluid was dark and dirty.

 

I changed the brake fluid and the brakes still behave the same.

I am still suspecting the ABS control unit acting up. Is there any way to trouble shoot the ABS unit?

 

I had the brake system checked by an independent Ford trained mechanic.

There were no ABS codes. Even though the brake booster held a vacuum, he suggested that the brake booster may be causing the problem.

I changed the brake booster. The braking performance improved and the ABS system acted more like I expected it should.

However, the front brakes were still not braking hard enough to stop quickly in a panic stop.

I took out the front ART brake pads and replaced them with Ford brake pads. The braking performance improved noticeably. Now the brakes work well. Stock Ford pads for me from now on.

As a note, I went through multiple bedding-in runs with the ART pads/rotors per ART instructions.

Even though the ART pads did not work that well for me, the ART rotors work very well! The brakes can be used hard without any rotor problems.