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Brake failure signal


CVA-42

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Hi, all. I'm a daily reader but haven't posted in a while. I have a "brake failure" issue. Yesterday, I flushed the brakes on my '08 1200GS with fresh fluid. Upon starting the engine afterwards, the yellow triangle icon appeared and went out almost immediately followed by the red "brake failure" signal about five seconds later. I took the bike for a ten mile ride hoping the signal would disappear but it didn't. The brakes seemed fine. I then started and turned the engine off several times with the same result. Figuring that I might have somehow gotten air in the lines, I flushed all the brake lines again today. Same result. The battery is a little over three years old so I checked the voltage and got 13.18 volts static and 14.15 with the engine running. I know that the "brake failure" signal can be caused by many things from a bad connection to a malfunctioning sensor to a bad battery to a bad modulator but the fact that the warning appeared immediately after the brake flushing indicates something. But what? I don't have a GS-911 although, at this point, I wish I did. Any thoughts? I should add that the warning appears not just with the bike running but with just the ignition turned on. I don't like that part. Thanks for any insights...

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Hi, all. I'm a daily reader but haven't posted in a while. I have a "brake failure" issue. Yesterday, I flushed the brakes on my '08 1200GS with fresh fluid. Upon starting the engine afterwards, the yellow triangle icon appeared and went out almost immediately followed by the red "brake failure" signal about five seconds later. I took the bike for a ten mile ride hoping the signal would disappear but it didn't. The brakes seemed fine. I then started and turned the engine off several times with the same result. Figuring that I might have somehow gotten air in the lines, I flushed all the brake lines again today. Same result. The battery is a little over three years old so I checked the voltage and got 13.18 volts static and 14.15 with the engine running. I know that the "brake failure" signal can be caused by many things from a bad connection to a malfunctioning sensor to a bad battery to a bad modulator but the fact that the warning appeared immediately after the brake flushing indicates something. But what? I don't have a GS-911 although, at this point, I wish I did. Any thoughts? I should add that the warning appears not just with the bike running but with just the ignition turned on. I don't like that part. Thanks for any insights...

 

Morning CVA-42

 

More than likely you are going to need to get a GS-911, or dealer computer, on that bike to get the brake failure code or codes to know what to look at.

 

A low or bad battery should have no effect on your 2008 (I-ABS gen II) operation as that system doesn't do it's low voltage checks until the engine is started.

 

One thing that you might try is to put the bike on center stand, then with key-turned-on but engine not running spin the rear wheel with your foot, then apply the front brake lever. See if the rear brake locks up smartly as you apply the front brake lever.

 

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D.R. - - Thanks for getting back. I ran the test that you described. The rear wheel did not stop when I applied the front brake lever. It did lock up smartly when I applied the rear brake lever. Only the front wheel stops when I apply the front brake lever. Why would the rear wheel stop when the front brake lever is applied?

 

With all the back-and-forth on the internet about battery voltage and effects on hexhead and camhead ABS, I didn't know that it doesn't matter...

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D.R. - - Thanks for getting back. I ran the test that you described. The rear wheel did not stop when I applied the front brake lever. It did lock up smartly when I applied the rear brake lever. Only the front wheel stops when I apply the front brake lever. Why would the rear wheel stop when the front brake lever is applied?

 

With all the back-and-forth on the internet about battery voltage and effects on hexhead and camhead ABS, I didn't know that it doesn't matter...

 

Afternoon CVA-42

 

That battery voltage thing is usually referring to the old 1100 bike ABS-2 systems as THOSE are the battery voltage sensitive systems. Your 08 GS with the I-ABS gen ll system is also sort of voltage sensitive but it doesn't check the voltage until after engine is running so basic battery voltage doesn't have much effect as the alternator is the supplying force during the voltage check process.

 

The rear wheel is linked to the front brake for normal stopping & THAT rear stopping force is supplied by the servo motor pump inside the ABS controller. If the servo motor doesn't run then the rear wheel won't lock up with bike on center stand with key on & rear wheel spinning.

 

There is no good way to know what is wrong with your brake system without having a failure code (my first guess would be a stuck brush inside the servo motor), but this is only a guess from afar based on past history with the system.

 

You might try the key-on rear wheel spin test again but use something hard but friendly to rap on the ABS controller pump motor while doing the test (if this by chance gets the system working again then suspect a stuck ABS servo motor brush). It is repairable at home but a very difficult repair & takes a fair amount of mechanical knowledge to accomplish.

 

You really need to find a way to get the ABS failure code(s) if possible as THAT will be the best guide as where to start looking for your problem.

 

As mentioned above sometimes rapping on the ABS servo motor can get it operating again (if a sticking brush is the problem).

 

Or, sometimes riding down a very rough or washboard road while lightly using the front brake lever can get the brush to free up slightly (again, IF a stuck brush is the problem).

 

 

 

 

 

 

 

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D.R. - - I didn't know about the rear brake servo assist on '08 models. So, yeah, I see the connection now in the test you prescribed. Doing a search on this site, I found a more detailed explanation on the subject that you put forth on 8/29/18. So, at present, it seems that I have non-ABS braking power in the rear and ABS braking power in the front. Correct? Can the bike be ridden safely as long as I am aware of the issue until I get a proper diagnosis? Also - - how do I get to the servo motor to try the tapping trick that you described?

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D.R. - - I didn't know about the rear brake servo assist on '08 models. So, yeah, I see the connection now in the test you prescribed. Doing a search on this site, I found a more detailed explanation on the subject that you put forth on 8/29/18. So, at present, it seems that I have non-ABS braking power in the rear and ABS braking power in the front. Correct? Can the bike be ridden safely as long as I am aware of the issue until I get a proper diagnosis? Also - - how do I get to the servo motor to try the tapping trick that you described?

 

Afternoon CVA-42

 

Not exactly, the ABS is the anti-lock part only. With the warning light on you probably don't have ABS (Anti-Lock) available but you also don't currently have linked braking available either.

 

You should be able to safely ride that bike but keep in mind that you won't have either ABS (Anti-Lock) or have front/rear linking available from the front lever. (to get rear braking you HAVE to use the rear brake pedal.

 

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D.R. - - How do I access the servo motor to try the rapping trick??

 

Evening CVA-42

 

It's not easy as the ABS controller is up under the fuel tank.

 

You m-i-g-h-t be able to look up under the fuel tank with a good strong light & see enough of the motor to get wooden dowel or broomstick up in there to rap on the motor. If not you will have to raise the fuel tank.

 

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  • 3 weeks later...

Well, I finally did get the bike to the dealer. They just called me and left a message that the "ABS pump is bad". I'm assuming this is the pressure modulator pump, part no. 1 34 51 7 715 109. They are proposing to replace the unit with no further investigation. Their quote for the part is just over $2,100 and labor around $200. They haven't determined if it's a motor brush hanging up or anything like that and, as I expected, they want to simply order the part, plug it in, and run my credit card. I get that and I understand why they do it that way but it is frustrating to someone like me who grew up in an era when many things actually got repaired when it was possible to do so instead of simply replaced. So - - what's my next move? Tell them to go ahead? Or collect the bike, take the modulator out myself, and send it to Module Masters? I am a pretty fair shadetree mechanic with a well equipped shop and I do most of my own maintenance and repairs on my bikes and cars unless I think it's something over my head.

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Well, I finally did get the bike to the dealer. They just called me and left a message that the "ABS pump is bad". I'm assuming this is the pressure modulator pump, part no. 1 34 51 7 715 109. They are proposing to replace the unit with no further investigation. Their quote for the part is just over $2,100 and labor around $200. They haven't determined if it's a motor brush hanging up or anything like that and, as I expected, they want to simply order the part, plug it in, and run my credit card. I get that and I understand why they do it that way but it is frustrating to someone like me who grew up in an era when many things actually got repaired when it was possible to do so instead of simply replaced. So - - what's my next move? Tell them to go ahead? Or collect the bike, take the modulator out myself, and send it to Module Masters? I am a pretty fair shadetree mechanic with a well equipped shop and I do most of my own maintenance and repairs on my bikes and cars unless I think it's something over my head.

 

Afternoon CVA-42

 

I would call Module Masters & explain your present condition then ask them if they will make the repairs & if so then how much.

 

Removing the ABS module (pump) is not complicated but a bit frustrating (nothing that most home mechanics can't handle though). Then after repair bleeding the system is no big deal.

 

 

 

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D.R. - - Thanks for getting back. I did call Module Masters after taking a look at their website. They confirmed that they would/could handle the job and even verified the part number with me. Said it should run about $250 including a five-year warranty. They did ask if I had the fault codes (which I don't) but I said I would see if I could get that info from the dealer. I then called the dealer and spoke to the Service Mgr. who I've known for a long time and have a good relationship with. He asked me what I wanted to do and I told him I couldn't see spending $2,300 when there might be a cheaper alternative. Then he (with no prompting from me) brought up Module Masters; said that they have sent several modulator units to them with good results; offered to call them about the job and give them the fault codes; and then offered to send the unit there himself. He even brought up the fact that their warranty would beat anything from BMW on a new unit. The Service Mgr. asked me to give him a follow-up phone call tomorrow after he has had a chance to talk to M.M. I think I'll just take an airhead ride over there in the afternoon. I know it will cost me somewhat more but at this point I plan to just let them handle the whole thing, in light of the fact that they've always treated me well and have even done me a few favors in the past gratis.

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  • 2 weeks later...
  • 2 months later...
On 10/1/2018 at 4:48 AM, dirtrider said:

 

 

One thing that you might try is to put the bike on center stand, then with key-turned-on but engine not running spin the rear wheel with your foot, then apply the front brake lever. See if the rear brake locks up smartly as you apply the front brake lever.

 

 

I’m researching the dreaded “brake failure” light, as I have the same problem on my 08 RT.  I thought I’d give this a try, and my rear wheel stopped instantly when I pulled the front brake lever...   once.  Now it won’t stop the rear wheel.  Seems like this is a really common (expensive) problem.

 

Curt

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6 hours ago, Curt Adams said:

 

I’m researching the dreaded “brake failure” light, as I have the same problem on my 08 RT.  I thought I’d give this a try, and my rear wheel stopped instantly when I pulled the front brake lever...   once.  Now it won’t stop the rear wheel.  Seems like this is a really common (expensive) problem.

 

Curt

 

Morning Curt

 

It could end up being  expensive, depends on the exact problem but your test sort of shows a possible stuck (or sticking) motor brush).

 

To know more you really should find a GS-911 (or dealers computer) then  read the stored brake failure code(s).

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Thanks, DR.  As I don’t have a GS911, it looks like I’ll need to make an appointment with the local dealer 😥 and get the codes.  I’ll let you know what I learn.  Somehow I feel a cashectomy coming on.

 

Curt

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  • 5 weeks later...

I just had my abs module rebuilt by MM.  2008 1200RT.  $250 and 5 days to send it back.  I wasn’t sure about doing the removal/install/bleed process, so I had the local dealer do it.  Sure beat their initial quote of $1800 + labor.  900 mile ride later, and the brake failure light is still out.  Happy customer!

 

Curt

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26 minutes ago, Curt Adams said:

I just had my abs module rebuilt by MM.  2008 1200RT.  $250 and 5 days to send it back.  I wasn’t sure about doing the removal/install/bleed process, so I had the local dealer do it.  Sure beat their initial quote of $1800 + labor.  900 mile ride later, and the brake failure light is still out.  Happy customer!

 

Curt

 

 

Morning Curt

 

Thanks for the follow up report. Did they say what they did? I presume your failure was due to a sticking brush???

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Yeah, somewhere I read that if you rap the motor with a dowel and a hammer, the light might go out.  It did on mine for about 50 miles, then came back on.  Called MM, and they said that’s classic brush sticking issue.  Sent it to them and she’s  fixed and on the road again.

Curt

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