I have a 2007 Freestar 4.2L and recently the ABS started acting up. Once every few times driving it, the ABS will activate under normal braking conditions, no slipping, etc. and then it will stop and the ABS light will come on. Then the ABS light will turn off after a while and it will be fine until a few days later. I haven't been able to check for any error codes yet, but I'm wondering if the ABS sensor could be going bad on one of the front wheels, I'm not sure if that would cause the behavior I'm seeing. Is there any reliable way to test that or diagnose the ABS? Or is there some other possible cause for something like that? Thank you!

 

A good part of the time a wheel speed sensor signal is dropping out. That can be caused by worn wheel bearing , junk between sensor and hub, and possible connection problem or sensor itself. There should be a code in the system telling you which wheel has the problem and you go from there.

 

Thanks for the tips, I had a chance to check for codes and came up with C1233-30 “FL wheel speed sensor input lost”. It sounds like that still doesn’t narrow it down much? I guess I’ll have to do some more investigation.

 

Unless a connector issue, chances are it’s a speed sensor/component issue. You might pull the sensor and check for visible debris or ring damage etc. Is your scan tool, reader only? Most decent scan tools will have functional tests to monitor/ match wheel speeds to prove out the drop out. Even a free FORScan download and a switchable ELM327 adapter makes for a very substantial diagnostic tool if a higher end unit is not a possibility...