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BMWCCA 149159
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Discussion Starter #1 (Edited)
This thread is designed to aid in those of us that will eventually get a failure caused by the ABS Module-Modulator-Pump. You typically get the DSC-ABS-Brake light warning on the dash.

If you are someone that has no interest in doing their own work or take it to your dealer or independent this thread isn't for you.

Background
I received this warning, the first warning I have received on my E93 since I picked it up in Munich 4/2007. I read the codes and discovered this is a common failure and will continue to be a common failure reasons why posted later. I tried to locate companies in the US that would rebuild the unit. The ABS module, that is the electrical brain that the connector is attached to isn't typically the problem. The problem is the other assembly called modulator and pump. I have only one car at the moment so I could not afford the downtime to research a repair. I purchased my unit from BMW of Minn for $940 which is the cheapest new part for this repair I could find. If you see my post on another members ABS post you will see the part numbers posted there. There are two part numbers one for 2007 to late 2007's and one for late 2007's on. I installed the unit, bleed the brakes and cleared the codes. Problem solved.

Now I can research the "why" on this part, Typically these things do not fail often why are we seeing this now? Well BMW changed the design and the suppliers provided parts to their design spec. Gone is the servo system and this system we have is a new design as of late 2006. This makes this part easy (3 on a 10 scale) to replace.

I investigated as many sites as I could and talked to a number of repair houses none in the US that would touch the modulator-pump just the module.

Here is what appears to be the cause of the failure. Remember this is my simple research on the subject but I plan to back this up with my failed unit repair to see if indeed the failure is caused by what I discovered. The pump on this unit is a high torque multi-brush electrical motor driving the pump. What happens is that this electrical motor gets brushes stuck and not making contact with the slip rings thus not allowing the motor to turn at the designated speed it is designed for thus throwing a fault code.

Well can you just replace the motor and be happy. Maybe someone can source the part but it is integral to the modulator and requires disassembly to attempt the repair. I will post a couple of sites that describe the problem and a Youtube video link that shows a BMW K1200 rider doing this repair, the same one I am going to try to see if that is what our problem is too.

Here is the youtube video 14 minutres long

and here is another link
http://www.i-bmw.com/showthread.php?t=41122&page=2

Both links are motorcycle related but if you have your failed system and compare it to the ones that are in the motorcycle thread and youtube you can see they are very close.

Can it be that simple as to a set of one stuck brush not making electrical contact with the slip rings? I am guessing yes because BMW isn't using different brush holders for the same series of electrical motors. The holders are plastic and the brushes are typically carbon or copper and seem to like each other too much and stick.

I will add to this thread as I begin to disassemble my failed unit and I will try my best using the camera equipment I have to take pictures to see if this theory is correct.

It can't be a coincidence that we are seeing this expensive unit fail when they typically never failed before especially once I discovered the design was changed in 2006.

By the way the company that replaced the brushes on the K1200 BMW motorcycles is called
http://www.modulemaster.com/en/index.php

I called them and talked to their rep and she stated no they would not touch our unit. Well since I am going to do this investigation and repair attempt myself I didn't feel it worth the time to explain to her it is the same unit slightly different design, etc. But if enough member want to get theirs repaired and it is the brushes they do that for I think $155.

Standby for updates
 

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Before I even got to your theory, I had already put my chips on the brushes... Why? That's exactly what used to fail on the pumps on the Mercedes MLs when forum members did autopsies.


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All bosch made abs fail after some years... My dad's peugeot had the same issue
 

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BMWCCA 149159
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Discussion Starter #5 (Edited)
My experience with over 12 BMWs is that I never incurred an ABS failure. Also Bosch is not the supplier of the components that failed. It is Continental Teves.

fdriller9
I used that thread and added to it. It is not diagnostic in nature just R&R but used it to aid in my install.

I have cut the tabs off today that holds the motor can inplace. I will next cut or drill a hole in the can to allow the tabs that hold the can to the housing and then remove the can exposing the motor. We should know if the brushes are the problem by tomorrow or in my case it is something else...
 

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BMWCCA 149159
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Discussion Starter #6
Update with Pictures

I disassembled the unit last night and opened it up this morning, cleaned it out, tested the motor this afternoon and reassembled the unit again this afternoon.

Brushes looked good not real dirty but impossible to tell if one was sticking because removing the motor from the motor can I dropped the darn thing since the magnets hold the motor in the housing requiring a lot of force to remove it. I didn't break the tabs that most do in the pictures or videos because I cut a rectangle and didn't drill a hole in the release tab area allowing my small flat blade screw driver to hold the tab in while removing the motor (see pics for the rectangle cut in the can). This motor is seriously over engineered (big surprise right). The can itself is something you expect to see on a large electric motor.

By the way the motor operates in an essentric manner so it looks like it is wobbling when you power it up. It makes sense as there are no gears or key ways on the motor shaft.

I used small dabs of epoxy to hold the motor to the modulator. I could have repinned the motor as was done by the supplier but if removal is needed it is very easy to cut the epoxy off.

Epoxy is drying now and I will need to cover the small cuts made when cutting the rectangles out. Most likely just black electrical tape will be sufficient to provide a water proof seal or I could use epoxy but not silicon which is known to KILL brushes. These brushes appear to be copper which is a quality brush material...
 

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BMWCCA 149159
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Discussion Starter #7
Can I state it was the brushes that caused my DSC-ABS-Brake lights or not? No I can't because I dropped the darn thing which could well have jarred the brushes back into position. I highly suspect that is what my problem was because it was not the module. The only way I can tell for sure is to do another one and NOT drop it. I cleaned the brush areas with CRC electrical contact cleaner and it was not as bad as I expected. The brushes at 59K miles hardly look worn too.
Reviewing the video the Youtuber's brushes didn't look that bad either but were stuck. I noticed after spraying with CRC and moving the brushes they appeared to be in much closer contact on the slip ring.

If this doesn't solve the problem that leaves the modulator as the issue which I might attack next once I do more research. Since there are 8 individual pistons and cylinders I would expect one of them to be stuck. If none appear stuck then it was the motor.

I will post pictures of the epoxy holding the motor where the tabs were and the cuts in the can itself which is much less damaging then drilling a hole as it saves the motor tabs from breaking...
 

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It might be wise to exercise the ABS regularly as the motor only turns when the unit is pulsing the brake pressure. At least that's how it works on my BMW motorcycle. ABS faults are typical of a low battery voltage as the computer continuously checks for sufficient power to operate the ABS motor. If the motor works and battery is good then faults at the wheel sensors are possible. I once triggered a fault by rolling backwards while hitting the starter on the bike. It's a very sensitive system.

I change brake fluid every two years to fight corrosion that can ruin an ABS controller. The issue here is that some controller circuits do not get flushed when bleeding at the wheels. The controller has additional bleed screws. My bike has an older version so bleeding the pump is not necessary. Still it would be a good idea to force ABS to work occasionally. Winter snow in a parking lot would be ideal.

Just some comments of indeed the car ABS unit is modelled after the ABS used in BMW motorcycles.
 

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BMWCCA 149159
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Discussion Starter #9
Unfortunately in 2006 BMW changed their design and removed the bleed screws so you CANNOT bleed the ABS modulator stand alone.
This isn't a battery issue
This isn't a module issue
It is either the motor which is the most likely issue or a stuck piston in the modulator.
Also my brakes are bled annually so it isn't bad brake fluid at all and the new design allows brake fluid to flow through the modulator flushing the pistons in the modulator.
You cannot bleed the brakes if it didn't do that since the output of the dual master cylinder goes directly to the modulator and from there it goes to each individual wheel cylinder.
I have not exercised the ABS but I plan to do that on a gravel road to be sure it is pulsing correctly.
I too thought of a modulator piston being stuck because of brake fluid contamination. That could still be possible and the only way to know for sure is to tear into the modulator and see if it is functioning correctly. That is the only component that has not been checked.
I have buttoned up the entire system and stored it away until I can locate instructions on how to check the modulator out...
 

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Unfortunately in 2006 BMW changed their design and removed the bleed screws so you CANNOT bleed the ABS modulator stand alone.
This isn't a battery issue
This isn't a module issue
It is either the motor which is the most likely issue or a stuck piston in the modulator.
Also my brakes are bled annually so it isn't bad brake fluid at all and the new design allows brake fluid to flow through the modulator flushing the pistons in the modulator.
You cannot bleed the brakes if it didn't do that since the output of the dual master cylinder goes directly to the modulator and from there it goes to each individual wheel cylinder.
I have not exercised the ABS but I plan to do that on a gravel road to be sure it is pulsing correctly.
I too thought of a modulator piston being stuck because of brake fluid contamination. That could still be possible and the only way to know for sure is to tear into the modulator and see if it is functioning correctly. That is the only component that has not been checked.
I have buttoned up the entire system and stored it away until I can locate instructions on how to check the modulator out...
There is a bleed procedure for the ABS/DSC Hydro pump via BMW diagnostic software. I normally activate this procedure through INPA to bleed brakes.

Not sure if this the same as what your're referring to.
 

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I don't have INPA, but how often do you guys recommend that we do the ABS bleed? I am happy with the firmness of my pedal feel after DIY bleed at the wheels, and will do that often enough so that my brakes shouldn't corrode. But I guess bleeding ABS won't help avoid fun2drive's issue, correct? Thanks, sorry for the semi-tangential question. Thanks for the thread, fun2drive.
 

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If the brake fluid reservoir never goes dry, there really is no need to bleed to the ABS/DCS pump.

Traditional brake fluid flush methods will be fine.
 

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I know that it is too late now but if the brushes are sticking I would have first applied 12 VDC and tapped the motor housing with a plastic hammer to see if the motor restarts. It's a simple technique from the old days when starter motor solenoids and carb floats got stuck. Usually a few taps with a hammer got you on your way again and it pinpointed the problem.

Why not try applying voltage now to see if the motor spins? You may even discover a seized pistol if the motor draws current but won't rotate.

I had a similar problem with a first generation mechanical injection system called Spica that was used on my Alfa Spyder. The injection system was copied from a diesel design and one piston seized up. The only solution was another injection module from the wrecker. It wasn't repairable.

Just a few more observations from the past that might help you unravel the cause of your ABS failure.

FYI, some of the motorcycle guys on their forum have simply bypassed the ABS module when it fails. The cost to replace it is too high for an older bike. I don't like this approach as ABS on a motorcycle is critical to staying upright but with a 15 year old bike, I too might just take the ABS unit out of the system.
 

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5DF0 and 5DF1 error codes E90 325d

Just wanted to share my experience in hopefully solving my DSC/ABS problem. Had the intermittent set of ABS lights which were really aggravating. After reading some other forum member's entries I came to the conclusion this could be caused by a couple of potential 'problems'.
  1. stuck brushes
  2. lack of ABS activation
I have given the metal part of the DSC module a whack with a hammer (not too heavy handed though) to hopefully release a stuck brush. I have then set off on a gravelly surface and slammed the brakes on causing the ABS to activate. As soon as I did the latter the lights on the dash went out immediately. Then just had to plug my Autel MS702 in to clear the fault codes. Will be monitoring things over the next few days but am feeling hopeful :beerchug:
Will update in a few days.
 

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Just wanted to share my experience in hopefully solving my DSC/ABS problem. Had the intermittent set of ABS lights which were really aggravating. After reading some other forum member's entries I came to the conclusion this could be caused by a couple of potential 'problems'.
  1. stuck brushes
  2. lack of ABS activation
I have given the metal part of the DSC module a whack with a hammer (not too heavy handed though) to hopefully release a stuck brush. I have then set off on a gravelly surface and slammed the brakes on causing the ABS to activate. As soon as I did the latter the lights on the dash went out immediately. Then just had to plug my Autel MS702 in to clear the fault codes. Will be monitoring things over the next few days but am feeling hopeful :beerchug:
Will update in a few days.
Hi, how is your car working after you did that? I have the same issue. Thank you
 

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E90 ABS lights

So far so good. When I think about it logically it makes sense that it is most likely sticking brushes. If the brushes stick in their guides then they may not complete the circuit that is checked by the on board computer. This is when the fault presents itself. If I was going to keep the car for any length of time I might have considered removing the abs module and check/modify/grease the brush guides but I'll be swapping my car later this year. If you do decide to try the method I used be careful not to hit any brake pipes :) Good luck and bear in mind you may have to get the fault codes cleared because they will still be stored in the on board computer.

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Now I can research the "why" on this part
You haven't asked: Why not?

This is no Japanese econo box requiring reliable service to compete. What you got there is a jewel of German Engineering.

The look....the feel....trouble free service dilutes the experience. See, the level of maintenance is a design goal, engendering pride; status to the owner affording the toll.

You are such a person, dear Bimmerfester.

.
 

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Thank you, sir. I am relieved that there is not (yet) another thing I have to worry about. :D
this statement is not correct, brake fluid is Hydroscopic, which means it absorbs moisture from the air, If you live in a humid climate, it will suck moisture from the air, and over time it will be enough to saturate the brake fluid, Where does the water go? its heavier than the brake fluid so it seeks the lowest level and will work its way down to the brake calipers. if the calipers are are cast iron it will rust them. the other issue is once enough water gets in the system, and you are working hard on the brakes, the moisture will boil and cause air in the lines, and then guess what you have no brakes,

BMW recommends 2 year interval for brake bleeding, and I suggest doing it, you might go 3 years but I wouldn't take a chance
 
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