How to know if Anti-Lock Brakes are Bad

[Jay White]

I have a 2001 ST, 2wd. Occasionally, when I do a hard brake (not panic), the ST slows quick, then locks up for a split second, then brakes again. Is this a sign of possible problems with my anti-lock brakes or some other brake problem? Don't want to throw away good money but want to fix this. It didn't do this when I first had the ST but only in the last few years. The truck has 135K on the odometer. Any help is appreciated. Thanks.

 

[Richard L]

That is how anti-lock brakes are supposed to work. When you brake, the wheel sensors determine if one of more wheels are not turning (locked up) then it releases the brake pressure on that wheel. The faster you are going, the more rapid the braking pulses are and can sound and feel like a jackhammer pounding on the brake pedal.



You did not say which wheel is locking up or at what speed you did the test, but It may be possible that you have a sticking caliper, small leak, or a rear drum brake out of adjustment and that is causing one wheel to lock up prematurely.



You need to check the brakes before you dive into the Anti-Lock brakes.



...Rich

 

[Yardsale]

Occasionally, when I do a hard brake ...

Do you mean that when you brake hard occasionally and it locks each time or that it sometimes locks when you brake hard? Subtle difference, but if you can determine under what conditions this occurs and it is repeatable, it may indicate the problem.

... the ST slows quick, then locks up for a split second, then brakes again.

Which wheel, or wheels, lock-up?



Have you checked to see of there is a brake fluid leak, or grease on the rotor or drum?

 

[Vic Sorlie]

How many brake fluid changes have you done during your ownership? If none or very few then I'd suspect you've got internal corrosion issues. I'd replace both front calipers, rotors and pads. On rear drums probably rear brake cylinders and check shoes and drums. Need a complete brake fluid flush.

 

[Yardsale]

That could cost hundreds of dollars and not fix the problem. Throwing parts at a problem can work, but I reserve that technique as a last resort.



Diagnose, then repair.

 

[swshawaii]

Ditto Yardsale. Thought an ABS malfunction would trip the warning light. Contaminated fluid can cause many issues, at the very least do a complete flush.

Anti-lock brake system (ABS) Momentarily illuminates when the ignition is turned to the ON position to indicate a system check. If the light remains on, continues to flash or fails to illuminate, have the system serviced immediately. With the ABS light on, the anti-lock brake system is disabled and normal braking is still effective unless the brake warning light also remains illuminated with the parking brake released.

 

[Vic Sorlie]

Lots of YouTube videos out there. I like Eric The Car Guy and Scotty Kilmer. Also found the one below from Auto Eclinic.