Feels like ABS is always active, even at very low speed with gentle braking.

[JoeS]

Fiesta ST 2007. When braking, even very lightly, it feels from the brake pedal like the ABS is operating all the time. Is this a common issue with the ST, and what is the fix please?

 

[TyphoonFiST]

Is there an ABS light on currently on the dash/ instrument cluster?

 

[crumpy]

This sounds like brake judder. I am not an expert but you might want to look for high spots on the rotors or pad marks that indicate uneven wear. You could have the caliper pins sliding unevenly causing pads to wear uneven against the rotor. Sometimes torquing the lug nuts unevenly can cause this issue as that's what I had on my car. Replaced the pads & rotors and the problem was gone. It is quite difficult to check condition of breaks with the wheels still on, sometimes I find the inner pads wear much more than the outer pads. Also careful when swapping out the pads as there is a difference between an inner pad and the outer pad.
Another thing to look out for is uneven tyre wear. Our break pedal is quite communicative so I wouldn't be surprised if the tyre is corded or something..

 

[TyphoonFiST]

Wheel bearing could be at fault or the Abs sensor dirty or tone ring of the wheel bearing has any could be dirty also not allowing the vehicle to fully see the signal.

 

[JoeS]

Is there an ABS light on currently on the dash/ instrument cluster?

No, there is no ABS light glowing.

 

[JoeS]

Wheel bearing could be at fault or the Abs sensor dirty or tone ring of the wheel bearing has any could be dirty also not allowing the vehicle to fully see the signal.

Can dirt make a difference to sensors, I thought they worked magnetically not optically?

 

[JoeS]

This sounds like brake judder. I am not an expert but you might want to look for high spots on the rotors or pad marks that indicate uneven wear. You could have the caliper pins sliding unevenly causing pads to wear uneven against the rotor. Sometimes torquing the lug nuts unevenly can cause this issue as that's what I had on my car. Replaced the pads & rotors and the problem was gone. It is quite difficult to check condition of breaks with the wheels still on, sometimes I find the inner pads wear much more than the outer pads. Also careful when swapping out the pads as there is a difference between an inner pad and the outer pad.
Another thing to look out for is uneven tyre wear. Our break pedal is quite communicative so I wouldn't be surprised if the tyre is corded or something..

There is certainly a significant judder. Is it more likely to be a problem on the front wheels or the back wheels?

 

[crumpy]

There is certainly a significant judder. Is it more likely to be a problem on the front wheels or the back wheels?

It was the fronts for me, specifically front left that happened two times. I now have 10k miles on a new set and it has gone away. The car just feels very easy when rolling along the highways. For me the issue did not present itself under braking alone. I had vibrations at 60-70 mph without any brake applied. This to me meant either rotor warp, a wheel out of balance or pads or rotors with high spots. From then on I decided I would torque my wheels myself and not let some tyre shop use airguns on my lug nuts. Worked out pretty well so far. Sometimes rust when parked can cause high spots on the rotors. You might try a bedding process to renew the pad and rotor surface before pulling them out to see if they need replacing (please do this in a safe environment, not near anyone else). Also when I replaced my rotors and pads I spent time bedding in the rotors and my rotor wear is much reduced. You might want to look this up. It was such a learning curve for me, I hope you get to the bottom of this.