Defective ABS?

[Darkwind]

I bought my 2011 M2 in February and all is fine and dandy, loads of fun to drive even if it does get buffeted about on the highways. For the most part we drive it on mountain roads.

Couple of months ago the brakes began acting up. Sometimes they activate as soon as the pedal is applied, other times I'm standing on the pedal to slow down or stop. It doesn't matter the road conditions, the distance, or the weather. More recently we hear grinding when braking, whether it's a hard brake or a gentle brake.

I took it to a local shop and they found nothing wrong, plus on the test drive noticed nothing unusual. That's not surprising as the problem is intermittent.

Drove down the mountain and dropped it off at the dealership (Ford) for them to look at as its under a Certified Pre-Owned Vehicle warranty; they looked at the pads, calipers, rotors, lines, found nothing wrong, but suggested I take it to their sister store which happens to be a Mazda dealership.

Well, it got really cold for awhile, so I'm leaving loads of slow-down room anyway, what with the snow and ice and all. Twice the brakes failed to work at all, thank goodness for the e-brake. Fortunately we ended up in a parking lot and they worked just fine getting to a more legit place. Second time, at 10 mph or less, they wouldn't work leaving the driveway and I ended up in a field. Worked fine when we pulled the car out and called the tow truck/roadside service.

The Mazda dealership took apart the brakes and did a full inspection, in addition to 2 test drives. One in the parking lot. They found nothing wrong. Both the master mechanic and the manager went over them. He said when the abs pump turns on it does make a grinding noise, and the brake pedal fighting back/pulsing is normal. Twenty miles later the brakes failed 4 times, heading through switchbacks and construction zones no less.

I did read elsewhere on this site that it's not unusual for the brakes to need floored when the abs activates, but this is all random! I love driving my little car, but not if it's going to kill me!

 

[DrWebster]

When the brakes "fail" to work, does the pedal just go to the floor but the car doesn't slow down at all? Or does the car slow down a bit and you hear a clicking noise from the front end? The ABS on the 2 is known to be a bit aggressive when it comes to kicking in, and when it does it can feel like the car isn't slowing down as quickly as you think it should. The ABS is also the quietest I've ever heard in a car; when the ABS in my Mazda 3 kicked in, it felt and sounded like a jackhammer.

It's possible to disable the ABS by pulling a fuse; I don't remember which specific one it is or where it's located (whether it's in the cabin or under the hood), but if you do a search on here about it I know there's a thread where it was discussed. Maybe you could try leaving that fuse pulled for a while and see if you prefer the brakes then.

 

[Mazda233]

Very difficult to diagnose over internet but I would suggest checking for a bad front wheel bearing. Several things will occur if the wheel bearing is loose. 1- noise 2- ABS sensor distance varies or the sensor is damaged 3- wobbling front rotor kicks the pads back and the master cylinder does not have enough volume to push the pads out in a single pedal stroke but after repeated strokes brakes return to normal until kicked back again.

 

[upthemiddle]

Looks like M233 beat me to it but I too would also suggest looking at the wheel bearings. Don't have any experience with Mazda's yet but when I was at a Honda dealership, I saw this problem a few times on 6th generation Accords where worn bearings would cause the rotors to push the pads back into the caliper and it would take several pumps to get the pads to where they should be for normal brake function. Just like when new pads are installed and you need to pump the pedal at first to get rid of the excess distance between the pad and rotor.

 

[Darkwind]

When the brakes "fail" to work, does the pedal just go to the floor but the car doesn't slow down at all? Or does the car slow down a bit and you hear a clicking noise from the front end? The ABS on the 2 is known to be a bit aggressive when it comes to kicking in, and when it does it can feel like the car isn't slowing down as quickly as you think it should. The ABS is also the quietest I've ever heard in a car; when the ABS in my Mazda 3 kicked in, it felt and sounded like a jackhammer.

It's possible to disable the ABS by pulling a fuse; I don't remember which specific one it is or where it's located (whether it's in the cabin or under the hood), but if you do a search on here about it I know there's a thread where it was discussed. Maybe you could try leaving that fuse pulled for a while and see if you prefer the brakes then.

So far I like this idea the best. To answer your question, everything's a 'sometimes'. Since I drive like a granny I have no problem with braking early, when there's a choice.Although when the brakes work like I'm used to, slowing/stopping happens too early. Curvacious mountain canyon roads don't often give a good view of what's ahead... and sudden stops often become necessary, which is when the abs likes to kick in, I guess, and slowing down isn't happening fast enough. You know, like driving down the highway and traffic suddenly goes from 75 to 0 in 2.5 seconds?

In all honestly, I was hoping there was a way to disable the abs... I'll check the owners manual as it should have the fuses all labeled.

Very difficult to diagnose over internet but I would suggest checking for a bad front wheel bearing. Several things will occur if the wheel bearing is loose. 1- noise 2- ABS sensor distance varies or the sensor is damaged 3- wobbling front rotor kicks the pads back and the master cylinder does not have enough volume to push the pads out in a single pedal stroke but after repeated strokes brakes return to normal until kicked back again.

Looks like M233 beat me to it but I too would also suggest looking at the wheel bearings. Don't have any experience with Mazda's yet but when I was at a Honda dealership, I saw this problem a few times on 6th generation Accords where worn bearings would cause the rotors to push the pads back into the caliper and it would take several pumps to get the pads to where they should be for normal brake function. Just like when new pads are installed and you need to pump the pedal at first to get rid of the excess distance between the pad and rotor.

I've tried pumping the brakes when I notice the pressure needs to be greater and greater before braking occurs. Sometimes it works... don't we just love intermittent problems? Bearings came to mind to me too, but I would have thought 3 garages would have checked that. The bearings the dealership checked had to so with 'steering steering linkages/wheel end play/bearings' and all that checked out fine.

 

[Darkwind]

DrWebster, I can't locate the abs fuse in my owner's manual fuse-box labels. I'm searching the forums, but no luck so far.

 

[cosh68]

Fuse as diagrams....





Shaun....

 

[DrWebster]

Here's the thread I was talking about for pulling the ABS fuse. I had to Google for it because the search here sucks.

http://www.mazdas247.com/forum/showthread.php?123823942-Disabling-ABS-Experiments

 

[Darkwind]

Thank you so much; I'm going to give it a try today, if these winds ever settle down.

 

[Darkwind]

Unfortunately that made the brakes worse. Unpredictable brakes are just too dangerous and we're taking that adorable little car back tomorrow to see if we can make a swap. Thanks so much for your help!