odd ABS activation
 

I've read the brake failure thread and hope I'm not heading down the same road.... Have a 2008 FEH with about 87,000 miles. Other than the dreaded MECS replacement last year, the car has been great. But about a month or so I noticed that occasionally when I'd be nearing a stop on city streets - slowing down from about 30 mph - the anti-lock brakes would kick in for just a second before the stop was complete. Since it was winter in Minneapolis, I just figured that the roads were icy. But it's been warm for a couple of weeks (no more ice) and it continues to happen. It's occasional - might happen a couple of stops in a row during some drives and then stop; never at all on others - and it only happens when I'm stopping after driving at a relatively low speed to begin with. Just before the ABS kicks in, I sometimes notice a clunk from the front end that's almost like an out-of-kilter spring.

I'd appreciate any ideas about what this might be. Also any thoughts on whether I need to take it to the Ford dealer or can just go with a regular mechanic. Now that I'm long past the warranty, I'd like to get a handle on which things need to be done by Ford and which can be handled properly - and more cheaply - by a standard garage.

Thanks,
Liz

Re: odd ABS activation
 

At low speeds even a slight suspension shift ("sometimes notice a clunk") might result in a quick shift from regen braking to frictional only and thereby a very brief ABS activation.

What happens is that instead of the wheel continuing to roll, roadbed traction overcoming regen braking friction, the suspension is loose, slight "play" front to back, and the wheel/tire suddenly shifts backward, against the direction of motion, just ever so slightly.

Ford hybrid = Ford dealer service.

Standard garage = NO.

While I hate to send folks to the rip-off artists at most Ford service departments(***) I suspect it would be rather unusual to find a third party with the intimate knowledge it takes to troubleshoot such a unique vehicle. Plus which, Ford will have ready access to any and all TSB's recalls, etc, plus experience with any consistent failures unique to the model but do not rise to the level requiring a TSB or recall.

*** All the while fully acknowledging that many third-party, aftermarket service shops, or known to be even better at "up-selling, worse at customer rip-offs.

Re: odd ABS activation
 

Liz,

It sounds like you are experiencing the symptoms of a broken/cracked ABS tone ring. Please read this thread and see if it matches your experience.

If this is your problem, the ABS/Tone ring cost $7.83 at rockauto.com. There is more information in the thread about what is involved in replacing it but one user on this thread did it himself. I don't see any express need to involve the Dealer for this part and any competent garage should be able to replace it.

Re: odd ABS activation
 

Thanks to both of you. It sounds exactly like a cracked tone ring. Not great news, but far less bad than being on the edge of a major brake failure! As someone who considered it a major accomplishment to change the turn signal bulb by myself, I'll definitely call on a professional to do the work for this one. The thread provided some great info about potential costs. Think I'll call my dealer to get an idea of what they'll charge me - since I'll be doing the 90K service and an alignment and a few other things already, maybe I can talk them down on this one. If not, I'll talk to the reliable guy who works on our non-hybrid - an aged Taurus. (Wwest - I'll follow your advice to stay with the dealer on most things, but sounds like this one could go either way.) One more question, if you don't mind: Is this something that needs to be fixed right away, or can it wait a few weeks? It's a crazy-busy time at work, so I may delay if it won't put passengers or vehicle at risk. Thanks again - this board is the best!

Liz

Re: odd ABS activation
 

ABS (and VSC/TC) is an EXTREMELY desireable SAFETY function..but then if this only happens at low speeds......

Re: odd ABS activation
 

Sounds like a tone ring. You can epoxy it to diagnose, but it should be replaced as a long term fix.

Re: odd ABS activation
 

I had a cracked tone ring with similiar issues. Replaced the tone ring and no more issues.