ABS is disabling itself

[aa0ut]

Application: 1997 Mystique Zetec Automatic w/o TC

When the ABS is called upon to do it's thing, the ABS light comes on and stays on until the next off/on ignition cycle. According to my user manual, this indicates a fault in the system, which responds by disabling itself.

This has occurred several times when applying the brakes on gravel. The right rear wheel seems to be prone to lock up first. I have not tried to force all four wheels into lockup at once.

Another observation is this: after starting the engine, the ABS light comes on momentarily, then extinguishes, according to plan. However, I do not feel or hear the pump do it's self test at 5 mph. I'm not sure if it is not occurring, or if I simply am unable to detect it.

My pocket scanner reveals no DTCs, but it is a cheap scanner and I believe it detects powertrain codes only.

Are there things that typically go wrong on these systems that I can investigate myself before I have it professionally diagnosed?

Regards... Mike

 

[todras]

Only a dealer can check ABS codes.

 

[starjammir]

Only a dealer can check ABS codes.

Not 100% true, my dads new code reader will read ABS codes, they are a little more money, around 180 bucks, but you can buy them.

 

[aa0ut]

Thanks for the replies guys.

Neither option you suggested fits my budget at this time, so I'll just sit on it for now.

Mike

 

[conbon]

I noticed I used to have ABS, but then the ABS light started coming on whenever I wasn't braking in a smooth, straight line (ie around turns, any uneven surface, hard braking, etc) and stays on until i turn the car off. A couple weeks back i came over a steep hill and there was a car stopped in front of me, instead of jsut changing lanes i got on the brakes (thinking i would stop in time), as i started to get closer i was pushing down on the pedal more and more until the last 5 feet when i stomped on it and to my suprise....slid into the car in front of me. I'm pretty sure my ABS sensor has shot craps on me, because i had ABS, light started acting funny, now i don't have ABS.....might be what happened to you.

 

[Rara]

Application: 1997 Mystique Zetec Automatic w/o TC

When the ABS is called upon to do it's thing, the ABS light comes on and stays on until the next off/on ignition cycle. According to my user manual, this indicates a fault in the system, which responds by disabling itself.

This has occurred several times when applying the brakes on gravel. The right rear wheel seems to be prone to lock up first. I have not tried to force all four wheels into lockup at once.

Another observation is this: after starting the engine, the ABS light comes on momentarily, then extinguishes, according to plan. However, I do not feel or hear the pump do it's self test at 5 mph. I'm not sure if it is not occurring, or if I simply am unable to detect it.

My pocket scanner reveals no DTCs, but it is a cheap scanner and I believe it detects powertrain codes only.

Are there things that typically go wrong on these systems that I can investigate myself before I have it professionally diagnosed?

Regards... Mike

Hi Mike.
Gravel and other deformable surfaces (snow is another common one) are the hardest for ABS programmers to manage, but thankfully, the fastest way to stop on those surfaces is by good old-fashioned locked up tires sliding. Thankfully, ABS calibrators have gotten much better in the last 10 years at detecting deformable surfaces. (Split mu is another really difficult situation to handle too, but out of this discussion )

If your faults are only occuring on gravel, I wouldn't be too terribly worried about it. But I would get the ABS codes pulled just to be sure. They will probably show up as random, or even specifically right rear wheel speed sensor faults. Fwiw, right rear is the most lightly loaded corner of the car under normal circumstances, so it doesn't surprise me at all that is the first to lock up.

In regards to the self test. I owned my CSVT for 9 years, and I can't specifcally recall any time where I noticed or felt the ABS doing its self-test.

And Todd and Bill are correct about the readers, you will need something a bit more sophisticated and Ford specific than your pocket scanner to get the ABS codes.

I noticed I used to have ABS, but then the ABS light started coming on whenever I wasn't braking in a smooth, straight line (ie around turns, any uneven surface, hard braking, etc) and stays on until i turn the car off. A couple weeks back i came over a steep hill and there was a car stopped in front of me, instead of jsut changing lanes i got on the brakes (thinking i would stop in time), as i started to get closer i was pushing down on the pedal more and more until the last 5 feet when i stomped on it and to my suprise....slid into the car in front of me. I'm pretty sure my ABS sensor has shot craps on me, because i had ABS, light started acting funny, now i don't have ABS.....might be what happened to you.

If you're story is accurately described, you would have still hit the car even if ABS had been functioning normally. If you only slid the last few feet, ABS would not have saved you. It still must work within the laws of physics.