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#996347 - 09/07/17 11:49 PM Brake Failure Light - ABS - '05 RT - w/ Servos  
Joined: Apr 2008
Posts: 350
rglassma Offline
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rglassma  Offline
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Joined: Apr 2008
Posts: 350
Hello All,

I have some interesting information that I would like to pass on to the board regarding my experience with the dreaded alternating brake failure lights.

I have had a reoccurring issue with the brake failure lights alternating at the 1 HZ interval for the past several months. I had tried various things to resolve the problem. All the while the brake fluid reservoir that are readily accessible were totally full, and a computer diagnostics indicated that the brake fluid was low. The following are the things that I had done (up until yesterday) and the outcomes:

1) Replaced Front Brake Pads - The brake self-test passed for several thousand miles of use until several days ago. Though the brakes seemed to work properly, the 1HZ alternating brake lights returned.

2) Checked both reservoirs again, they seemed fine. But added a little fluid anyway.

3) Checked the switch underneath the rear brake pedal to determine if it operated normally. It did.

4) Traced the ABS sensor wire down and identified that the cables were not too tight, corroded, or stressed in any way.

5) Examined all pads, calipers, rotors, and brake movement to insure proper activity. All looked fine.

Honestly, I was stumped.. I knew that if I took my bike in to BMW, it was going to cost me a fortune regardless. So, I opted to take the high road:

1) Research Articles, primers, videos on how to disassemble the bike and expose the ABS control unit and go from there.

2) Between myself, my nephew helper, and my great buddy Wayne, we disassembled the bike, removed the fuel tank (not as bad as I thought), and started to inspect the fill reservoirs for the front and rear brakes. We found the problem !!! The front circuit on the abs unit was empty !!! No fluid at all.

We filled the reservoir up with a sipping straw slowly. We also examined the cables leading to the front brakes and found that there was grit on the area above the front wheel where the cable has a transfer screw on each side to a second cable that leads to the front caliper. One of the bolts was loose. So I tightened up the bolt. This may have accounted for some of the loss of fluid.

I then contacted the BMW dealer that did the last flush on the bike (which of course I paid full price for) and was advised how else a leak could have occurred. He also admitted that he may not have filled the reservoir up enough, during the last flush. That also could have contributed to the problem as well. I was further advised that if the bike had fallen over, brake fluid could have drained out of the drain vent.

So, there you have it. Upon filling the fluid, we turned the ignition on and the alternating warning failed to appear. So we then, reinstalled the fuel tank, started the bike (allowing it to go through the self test as much as possible). Only the single brake warning came on (normal of course). Once the bike was back together, I took it for a test drive. No Warnings at all.

Another buddy Greg, brought over his GS911, ran the tests, cleared the warnings, and the GS911 showed no other warnings.

Hopefully the problem is solved.

For those that have a similar problem, please be advised that the following links and information proved to be extremely beneficial at enabling my team to resolve the problem with no ABS brake experience:


https://www.youtube.com/watch?v=TpI05pWUp-Y

https://www.youtube.com/watch?v=Etex4BpLSKM

http://www.ukgser.com/technical/nick/Brake%20bleeding%20%28All%20BMW%20EVO%20systems,%20%2704-%2707%29.pdf - This doc has most of what you need if not all.

Without the information above I would be at the mercy of the dealer.

I wish to thank this forum and all contributing members for your help.

This place is an incredible resource !!!



Bob Glassman

Last edited by rglassma; 09/07/17 11:54 PM.
#996391 - 09/08/17 05:34 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: rglassma]  
Joined: May 2014
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NickInSac Offline
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NickInSac  Offline
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Joined: May 2014
Posts: 225
Northern Ca, Sacramento
This little guy makes all the difference for me.

http://www.beemerboneyard.com/abs3funnel.html

I've done four brake fluid flushes on my '06.

Good job finding your problem and solving it!


2006 R1200RT in Sacramento CA
#996421 - 09/09/17 02:26 AM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: rglassma]  
Joined: Apr 2008
Posts: 350
rglassma Offline
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rglassma  Offline
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Posts: 350
Thanks. Yeah, I am sure when it is necessary for another flush, that funnel will become a part of my arsenal .. We have a couple of years to worry about that for now.

Sure seems like BMW maximized the design of these bikes so that it takes more time to work on them...

#997182 - 09/18/17 11:49 AM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: rglassma]  
Joined: Jul 2005
Posts: 48
Dave Glen Offline
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Dave Glen  Offline
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Posts: 48
St Arnaud, Vic, Australia
G'day all,
I have had a similar but different problem with my bike the last time I went for a ride, its a 2005 R1200RT 210,000 klms. Brake fluid changes every 2 years.

The red triangle warning and fast flashing 'brake failure' lights came on however this time it was different to other times this has happened where it was due to low battery voltage.

This time the speedo continued working, the front servo worked, brake lights worked but no auto rear brakes and no rear brake servo noise.

I have checked everything as per rglassma post including removing the fuel tank and checking the fluid levels.

I can only assume that the rear servo is knackered and am wondering if anyone on the forum has repaired one or do I change the bike to non-abs. I have checked on a number of forums youtube etc and have only found one comprehensive pull down and what looks like fitting of pump seals, but it is in french so a fair bit is not understood by me.

Anyway any ideas to where to go to now would be greatly appreciated.I don't fancy paying BMW Australia $3600 approx for a new one.

Regards
Dave Glen
St Arnaud, Australia

#997186 - 09/18/17 12:24 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: Dave Glen]  
Joined: Jun 2010
Posts: 13,198
dirtrider Offline
The Oracle
dirtrider  Offline
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Posts: 13,198
Ohio
Originally Posted By: Dave Glen
G'day all,
I have had a similar but different problem with my bike the last time I went for a ride, its a 2005 R1200RT 210,000 klms. Brake fluid changes every 2 years.

The red triangle warning and fast flashing 'brake failure' lights came on however this time it was different to other times this has happened where it was due to low battery voltage.

This time the speedo continued working, the front servo worked, brake lights worked but no auto rear brakes and no rear brake servo noise.

I have checked everything as per rglassma post including removing the fuel tank and checking the fluid levels.

I can only assume that the rear servo is knackered and am wondering if anyone on the forum has repaired one or do I change the bike to non-abs. I have checked on a number of forums youtube etc and have only found one comprehensive pull down and what looks like fitting of pump seals, but it is in french so a fair bit is not understood by me.

Anyway any ideas to where to go to now would be greatly appreciated.I don't fancy paying BMW Australia $3600 approx for a new one.

Regards
Dave Glen
St Arnaud, Australia



Morning Dave

You can't effectively repair it if you don't know what is wrong with it.

My suggestion is to get a GS-911 or dealer computer on that bike to grab the brake failure code(s).

Once you know WHAT part of the brake system has failed we can help you formulate a plan on how to identify & properly repair it.

You can remove the servo/ABS part of the braking system but you will have to retain the electronics part of the ABS controller (needed for speedometer & wheel speed input). That will require making a water tight sealed cover for the ABS electronics)


D.R. ___
Sent from my rotory dial wall phone!
#997257 - 09/18/17 11:38 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: dirtrider]  
Joined: Jul 2005
Posts: 48
Dave Glen Offline
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Dave Glen  Offline
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Joined: Jul 2005
Posts: 48
St Arnaud, Vic, Australia
Thanks DR, as always your advice is spot on the money.

I forgot to say that during the ride we stopped for a drink and when I started the bike all was ok until about 10 klms down the road I slowed for a potential U turn driver and the warning light started flashing.

I live in a small town 250 klms from the nearest BMW dealer, I had thought of getting a GS-911 and thought the only other BMW rider in town might have been interested in sharing the cost. He thought it was a good idea that we have one but only if he could borrow mine, so that hasn't happened.

I have disconnected the battery and will leave the bike for several hours to see if a reset might happen.

If that doesn't work I will strip it down and check the servo motors brushes and wiring and the pumps and replace seals (mostly O rings) and the motor/pump seal.

I checked out the frenchman's videos in full last night and this unit is like all mechanical devices in that it appears complex but it is just an assembly of individual components non of which are complex. So mechanically unless I can't buy a particular part which may be unavailable it should be able to be repaired, then there is the question of the electronics.

If I pull it down I will take photos so hopefully someone else on the forum won't be going into this situation blind,

Regards

Dave

#997258 - 09/18/17 11:43 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: Dave Glen]  
Joined: Jun 2010
Posts: 13,198
dirtrider Offline
The Oracle
dirtrider  Offline
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Joined: Jun 2010
Posts: 13,198
Ohio
Originally Posted By: Dave Glen
Thanks DR, as always your advice is spot on the money.

I forgot to say that during the ride we stopped for a drink and when I started the bike all was ok until about 10 klms down the road I slowed for a potential U turn driver and the warning light started flashing.

I live in a small town 250 klms from the nearest BMW dealer, I had thought of getting a GS-911 and thought the only other BMW rider in town might have been interested in sharing the cost. He thought it was a good idea that we have one but only if he could borrow mine, so that hasn't happened.

I have disconnected the battery and will leave the bike for several hours to see if a reset might happen.

If that doesn't work I will strip it down and check the servo motors brushes and wiring and the pumps and replace seals (mostly O rings) and the motor/pump seal.

I checked out the frenchman's videos in full last night and this unit is like all mechanical devices in that it appears complex but it is just an assembly of individual components non of which are complex. So mechanically unless I can't buy a particular part which may be unavailable it should be able to be repaired, then there is the question of the electronics.

If I pull it down I will take photos so hopefully someone else on the forum won't be going into this situation blind,



Evening Dave

Unfortunately the thing that you can't easily test or replace (not available) is the internal servo control pressure sensor.

That pressure sensor is one of the usual causes of a servo failure to operate.


D.R. ___
Sent from my rotory dial wall phone!
#997266 - 09/19/17 01:59 AM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: dirtrider]  
Joined: Jul 2005
Posts: 48
Dave Glen Offline
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Dave Glen  Offline
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Posts: 48
St Arnaud, Vic, Australia
Once again, thanks DR,

I have made inquiries re having the unit repaired and the service tech basically said the same thing. I wonder if I take it out and swap over the pressure sensors would that prove that it was RS.

The ABS repair place doesn't repair particular these units.

I would like to take it to the dealer but it is a nightmare trip on a bike, firstly kangaroos then a dealer that doesn't give a rats arse and only takes bikes for service on any day on a first in first served basis so even though you are booked you might not be attended to until late in the day then more kangaroos coming home. The next nearest dealer is 450 klms away and they are good blokes but it also means staying the night as well as kangaroos each way.

I think I may ask around my local Ulysses Club branch (225 klms away) to see if any of the Beemer riders have a GS-911

Regards
Dave

#997577 - 09/23/17 02:41 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: rglassma]  
Joined: Apr 2008
Posts: 350
rglassma Offline
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rglassma  Offline
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Joined: Apr 2008
Posts: 350
Buying a GS-911, if you have the money to do so, is a great investment if you are going to keep your bike, or are planning on owning a BMW. It is like turning on a light bulb in a dark room. Remember though, the older units do not work with the LC model. So, if you buy a used one, and then you change bikes to a new model, don't be caught unaware.

#997607 - 09/23/17 11:33 PM Re: Brake Failure Light - ABS - '05 RT - w/ Servos [Re: rglassma]  
Joined: Jul 2005
Posts: 48
Dave Glen Offline
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Dave Glen  Offline
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Joined: Jul 2005
Posts: 48
St Arnaud, Vic, Australia
G,day all,
An update to the ABS module failure.
I wasn't able to borrow a GS-911 and going to the dealer was out of the question, so I decided to pull the unit out and see if the only fixable part was causing the problem.
I dismantled the unit and found that it was spotlessly clean inside, both servo motors and pumps were ok which meant that 1 or all pressure sensors were buggered. There are no replacement parts available so I have done the ABSectomy.
The brakes are working fine and I have blanked out the dashboard warning lights.
I can write out instructions on how to do the whole job if anyone is interested.
Thanks for everybodys replies, I would love to have a GS-911 but they are $700 Au here, thats the price of a code 0 headsail for my little boat I know what would get more use.

Regards
Dave Glen

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