# Very strange brakes



## papereater (Sep 16, 2016)

BMW 328i, 2009, only 38,000 miles. Normally brakes feel/work fine, except once in a while you apply them gently and the feel you get is the brakes will "skip' and "jerk" unevenly. With a audible scraping sound. Then they work fine again the rest of the way on that trip. 

There is no brake warning light either. I fear that even if I remove a wheel to visually inspect I may not find a thing. 

What to do?

Thanks,
paper


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## Guap0_ (Dec 2, 2017)

I bet that the jerking is the stupid anti lock thing but that doesn't account for the noise. Pull the fuse. Every winter I have to remove mine or I'll definitely have an accident.


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## mark sr (Jun 13, 2017)

When anti lock is engaging the brake pedal will 'jump' up and down.
IMO it's always a good idea to visually inspect the brake pads, rotor, etc.


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## papereater (Sep 16, 2016)

Thanks, people. Good to know. Guess I should inspect brakes asap. Oh- I should have mentioned that other warning lights come on , intermittenly, probably indicating another (yes, another) failed speed sensor. Had 2 replaced since car was new. Gees. Ive been putting it off. Not sure which wheel now has a failed sensor. 

Anyway, wonder if thats related to the problem.......Why would a bad speed sensor affect braking?? So far, the only thing I see that sensor affecting is the cruise control. Who cares about cruise around town(?).


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## Guap0_ (Dec 2, 2017)

I always look at the right front first, if I'm not sure where the problem is.


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## 47_47 (Sep 11, 2007)

Car sits a lot, brake dust may be imprinting brake pad outlines onto rotors causing grinding / scraping noise, until imprints are burnished off during braking.


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## chandler48 (Jun 5, 2017)

> Anyway, wonder if thats related to the problem


Of course it is. The speed sensor is an integral component to the ABS. If it is malfunctioning, then the ABS won't work properly and you can encounter that jerking, pedal movement, etc.


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## 47_47 (Sep 11, 2007)

chandler48 said:


> Of course it is. The speed sensor is an integral component to the ABS. If it is malfunctioning, then the ABS won't work properly and you can encounter that jerking, pedal movement, etc.


Don't know about BMW, but for domestics, any ABS fault will disable the system and you will be left with basic brakes. You will also loose traction control and ABS fault lite will come on.

Does this noise or strange pedal only occur one time after a start during the first low speed application? Again back to domestics, ABS brakes need to initialize once every car start. This occured at ~ 7mph for GM and if you applies the brakes during this initialization, the pedal would be low or bounce.


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## Guap0_ (Dec 2, 2017)

> Don't know about BMW, but for domestics, any ABS fault will disable the system and you will be left with basic brakes


I'm left with NO brakes. That's why I pulled the fuse. I've already slid through intersections at 2 MPH on snow. I wonder if the same guy who invented the shoulder harness invented ABS.


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## de-nagorg (Feb 23, 2014)

My first impression is a warped rotor.

Maybe a wheel bearing that is looser than the other side.

Checking it out is a very good idea, you do not want failed braking .



ED


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## Gregsoldtruck79 (Dec 21, 2017)

papereater said:


> BMW 328i, 2009, only 38,000 miles. Normally brakes feel/work fine, except once in a while you apply them gently and the feel you get is the brakes will "skip' and "jerk" unevenly. With a audible scraping sound. Then they work fine again the rest of the way on that trip.
> 
> There is no brake warning light either. I fear that even if I remove a wheel to visually inspect I may not find a thing.
> 
> ...


38K miles ? Did you buy the car new or know its history of brake maintenance ? It may have the original brake pads on it and time for a pad/rotor tune-up. Pads could be metal to metal on some spots. JMO


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## Brainbucket (Mar 30, 2015)

Rule of thumb. Front brakes usually wear out around 30,000 miles. Rear around 50.000 to 60.000 miles on rear wheel drive cars. This also depends on driving habits and/or hwy or city driving. If the speed sensor is bad, that could cause your issue. BMW likes OEM type pads. Just ask for OEM type pads at the parts store. Make sure you clean the rotors off with brake clean before you install pads. If you don't, it may cause squeaking and other noises. Mercedes-Benz is the same way. Learnt the hard way.:vs_cool:


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## mark sr (Jun 13, 2017)

> A Rule of thumb. Front brakes usually wear out around 30,000 miles. Rear around 50.000 to 60.000 miles on rear wheel drive cars


A lot depends on the vehicle. My 2010 jeep with 66k still has the factory pads in decent shape on the front but I had to replace the rear pads at 55k because they were completely worn out.


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## w0j0 (Dec 29, 2017)

mark sr said:


> A lot depends on the vehicle. My 2010 jeep with 66k still has the factory pads in decent shape on the front but I had to replace the rear pads at 55k because they were completely worn out.


Yeah, my vw golf would consume rear pads at about twice the rate compared to the fronts.

But, I will concur that the OP's brake issue can likely be attributed to a malfunctioning ABS system. I rehabed a grand prix that had a similar issue. To make the car safe to drive, I disconnected the large wiring harness from the ABS controller, until I could troubleshoot the exact cause. Turned out that a wheel sensor wire had been rubbed through. I've also seen where rust or ferrous metal dust collects on the wheel sensors and a simple cleaning restores function.

Sent from my mobile look-at device


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## papereater (Sep 16, 2016)

Wow, go out to eat Mexican for lunch and get back to see sooo many replies! Thanks, people!!

I am the original owner. I treat all my cars with TLC. Gentle braking/clutch action (I own MT's). I go many miles before pads wear out. Also, shouldnt the pads have the "squeel" tabs, indicating pads getting thin?

BM's are notorious for speed sensor defects. Im overdue. Just skeptical if its related. I am waiting for BM to send me my recall notice for the cab blower motor overheat problem. But so far nothing in the mail. Will check with them tomorrow. Meanwhile, gonna jack up the car right now and look at the pads/rotor..........


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## papereater (Sep 16, 2016)

47_47 said:


> Does this noise or strange pedal only occur one time after a start during the first low speed application? Again back to domestics, ABS brakes need to initialize once every car start. This occured at ~ 7mph for GM and if you applies the brakes during this initialization, the pedal would be low or bounce.


No. Not necessarily on the 1st application. Random, it appears.


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## papereater (Sep 16, 2016)

Guap0_ said:


> I bet that the jerking is the stupid anti lock thing but that doesn't account for the noise. Pull the fuse. Every winter I have to remove mine or I'll definitely have an accident.


Need to find the fuse. Any idea? If I pull it, just pop it back in, then all will work normally?


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## papereater (Sep 16, 2016)

de-nagorg said:


> My first impression is a warped rotor.
> 
> Maybe a wheel bearing that is looser than the other side.
> 
> ...


Doubt warped rotor. On my other cars I always feel it in the foot.


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## papereater (Sep 16, 2016)

Gregsoldtruck79 said:


> 38K miles ? Did you buy the car new or know its history of brake maintenance ? It may have the original brake pads on it and time for a pad/rotor tune-up. Pads could be metal to metal on some spots. JMO


Orig owner. Doubt I need new pads- 4 wheel rotors, gentle braking, using MT to slow down car, etc........but never know- Im checking it now (within say, 5-15 minutes......)


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## papereater (Sep 16, 2016)

OK, pads are good- still have 9mm left on outside pad. Inside looks about the same. Rotor turns sooo smoothly by hand, no kinking/binding, etc. Very smooth. That fuse, behind glove box, so hard to get to. Diagram shows 6 different fuses for abs. What??? Im not gonna yank 6 fuses. Owners manual is worse- the section on fuses is just a short paragraph, indicating to go to glove box. 

Im done at this point, people. Im convinced knowing BM, who started the proprietary diagnostics idea to generate $$ (and all the rest followed) they are the only ones with the computer to diagnose this. Sheesh.


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## w0j0 (Dec 29, 2017)

Open the hood, follow brake lines from master cylinder to box with wiring harness. Pull the wiring harness. This will disable ABS

Sent from my mobile look-at device


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## Guap0_ (Dec 2, 2017)

Can you post the list of fuses? You only need to pull the fuse that makes the ABS light on your dash light. That's what I do with mine.


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## mark sr (Jun 13, 2017)

> I am waiting for BM to send me my recall notice for the cab blower motor overheat problem. But so far nothing in the mail.


With most vehicles you can type in your VIN and do a search for recalls and TSBs. My jeep had an unpublished recall on the transmission lines which I stumbled across looking for info on how to replace it myself [takes a special tool]


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## Gregsoldtruck79 (Dec 21, 2017)

Your DIY professional worry wart here, feels a need to mention something here.  

The possible scenario : Someone disables a safety feature on their car and then after doing so, unfortunately has a crash injuring others and they are found to be at fault.

There will be attorneys that will be representing the injured that will turn every stone over, to assure his/her clients' get all the money he can get for them (with his % too). 

Then to their defense, if the driver at fault makes the claim their brakes failed, the attorney's accident investigation team will find a unplugged ABS harness on the wrecked vehicle. 

Which may mean the court could hear the words from the attorney, " intentional act of negligence on the drivers behalf that caused the accident " . Not good for the defendant and good for the plaintiff(s) . 

All JMO though...


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## w0j0 (Dec 29, 2017)

Gregsoldtruck79 said:


> Your DIY professional worry wart here, feels a need to mention something here.
> 
> The possible scenario : Someone disables a safety feature on their car and then after doing so, unfortunately has a crash injuring others and they are found to be at fault.
> 
> ...


I hear ya. In the case of the grand prix I worked on, though, not having ABS (and knowing it) was a lot safer than the ABS activating itself whenever it felt like. Sounds like that may be the case for the OP, too. Not suggesting it as a long term fix.
Used to be that no vehicles had ABS and at least one of mine currently does not (97 jeep wrangler, no ABS from the factory). Just need to know what to expect from your vehicle when you provide input to it.

Sent from my mobile look-at device


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## mark sr (Jun 13, 2017)

> Just need to know what to expect from your vehicle when you provide input to it.


While I've resigned myself to the fact that today's car's have ABS, I instinctively let go of the brake pedal and hit them again when a tire locks up. The pedal jumping up/down while ABS is working feels strange to me.


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## papereater (Sep 16, 2016)

Good tips. Thanks. will get to these ideas asap. Work week now.......


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## de-nagorg (Feb 23, 2014)

Make it sooner, if failure occurs, and you cannot stop, the consequences are drastic.


ED


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## Dave Sal (Dec 20, 2012)

papereater said:


> Wow, go out to eat Mexican for lunch and get back to see sooo many replies! Thanks, people!!
> 
> I am the original owner. I treat all my cars with TLC. Gentle braking/clutch action (I own MT's). I go many miles before pads wear out. Also, shouldnt the pads have the "squeel" tabs, indicating pads getting thin?
> 
> BM's are notorious for speed sensor defects. Im overdue. Just skeptical if its related. I am waiting for BM to send me my recall notice for the cab blower motor overheat problem. But so far nothing in the mail. Will check with them tomorrow. Meanwhile, gonna jack up the car right now and look at the pads/rotor..........


BMW's have a wear sensor in two of the calipers. One in front and the other in the rear. When the pads wear down to the point where they need replacing the wear sensor gets worn away which triggers a warning light on the dash. When you replace the pads you also replace the wear sensor.


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## papereater (Sep 16, 2016)

Dave Sal said:


> BMW's have a wear sensor in two of the calipers. One in front and the other in the rear. When the pads wear down to the point where they need replacing the wear sensor gets worn away which triggers a warning light on the dash. When you replace the pads you also replace the wear sensor.


But remember- I posted above that I still have 9mm left on pads.


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## papereater (Sep 16, 2016)

Guap0_ said:


> Can you post the list of fuses? You only need to pull the fuse that makes the ABS light on your dash light. That's what I do with mine.


Yes, and they are: 04, 12,26, 67,82,90. Burried behind the "glove" box. Why do we still call it glove box, when those days are gone. 

So what do I do to all these fuses?


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## Dave Sal (Dec 20, 2012)

Maybe your sensor wire is damaged.


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## Guap0_ (Dec 2, 2017)

You listed the numbers, what about the names? For example, brake, stop, etc...


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## Gregsoldtruck79 (Dec 21, 2017)

All LOT of reading material about the BMW ABS issue. Here............


https://www.bimmerforums.com/forum/showthread.php?742586-DIY-Complete-ASC-delete-with-no-ABS-light-fault!


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## papereater (Sep 16, 2016)

Guap0_ said:


> You listed the numbers, what about the names? For example, brake, stop, etc...


No, theyre all for abs (and a triangle with a circle inside), believe it or not, according to that chart. What is one to think? Just the same, I cant get in there unless with some special fuse extractor tool, with a 12-18" extension "tongs".


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## Guap0_ (Dec 2, 2017)

Aren't the names on the cover? The ABS fuse in my van says brake. The brake light fuse says stop. Why don't you want to post the names?


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## papereater (Sep 16, 2016)

Gregsoldtruck79 said:


> All LOT of reading material about the BMW ABS issue. Here............
> 
> 
> https://www.bimmerforums.com/forum/showthread.php?742586-DIY-Complete-ASC-delete-with-no-ABS-light-fault!


Right, but, wondering if it applies cuz mine is a 2009 and that thread is from 2005. Not sure, still, if I am ready to mess with resistors........


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