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Brake Failure Warning Light staying on


RichardSpag

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Hi Guys/Gals,

 

My 2011 RT has just started an odd problem which I'm wondering could be related to the original battery (106k miles old): Turning the ignition key, the usual cycling of lights occurs with the brake failure remaining flashing. Starting the bike brings on the yellow triangle for a moment and the brake warning stays flashing. Moving off cancels the brake light and brake operation is normal. The brake light can come on and stay solid after a mile or sometimes after 300 miles. The brakes dont seem to change in their operation and the reservoir level is constant. Stopping the bike and turning off the ignition and restarting immediately will make the brake light warning return after a short distance. Stopping the bike for longer (i.e. refueling) can result in another 200 miles before it comes on during riding (usually when the brakes are not being applied).

I wondered if the electrical demand (seat, handlebars and jacket operating) was causing a power dip of some sort? All of the bike journeys are motorway miles (100 miles per day) - so I dont think that charging is a problem (it has a new alternator belt) - so I wondered if it could be either a) battery age related or b) moisture/dirt getting somewhere it shouldn't! I have a GS911 -but my laptop that I use to run it is poorly at the moment!

 

Thanks in advance for any collective wisdom on the matter!

 

Cheers

 

Richard

Edited by RichardSpag
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Hi Guys/Gals,

 

My 2011 RT has just started an odd problem which I'm wondering could be related to the original battery (106k miles old): Turning the ignition key, the usual cycling of lights occurs with the brake failure remaining flashing. Starting the bike brings on the yellow triangle for a moment and the brake warning stays flashing. Moving off cancels the brake light and brake operation is normal. The brake light can come on and stay solid after a mile or sometimes after 300 miles. The brakes dont seem to change in their operation and the reservoir level is constant. Stopping the bike and turning off the ignition and restarting immediately will make the brake light warning return after a short distance. Stopping the bike for longer (i.e. refueling) can result in another 200 miles before it comes on during riding (usually when the brakes are not being applied).

I wondered if the electrical demand (seat, handlebars and jacket operating) was causing a power dip of some sort? All of the bike journeys are motorway miles (100 miles per day) - so I dont think that charging is a problem (it has a new alternator belt) - so I wondered if it could be either a) battery age related or b) moisture/dirt getting somewhere it shouldn't! I have a GS911 -but my laptop that I use to run it is poorly at the moment!

 

Thanks in advance for any collective wisdom on the matter!

 

Cheers

 

Richard

 

Morning Richard

 

It could be a lower system voltage causing the problem but it should self correct once you start riding & the system voltage comes back up.

 

Without stored brake failure codes it is about impossible to give a firm answer-- but your problem sort of points to a wheel speed sensor issue, or a cable going to a wheel sensor having an issue (like front L/H brake rotor rubbing the speed sensor cable).

 

It could also be a servo-motor brush sticking issue (servo-motor runs when you use the front brake lever as it also operates the rear brake from the front lever).

 

For normal riding you probably won't notice a brake performance issue (especially if you also use the rear brake pedal) but with the warning light on you will not have ABS available & probably not have front to rear linked braking.

 

Added: You might also check front & rear wheels for loose wheel bearing allowing the wheel to move around causing a speed sensor pick-up error.

 

 

 

Edited by dirtrider
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Dirtrider,

 

Your suggestion regarding the front sensor might be on the money. The wires to this wore through a couple of years back and I spliced it back together again. Perhaps the splice has started to fail and I have moisture/corrosion getting in there (its been very wet here in the UK!).

 

Ill get my GS911 on to it at the weekend and report back!

 

Cheers

 

Richard

 

 

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It transpired that it was the good old wire chaffed against front disc jape! The phrase about fool me once shame on you,fool me twice.....! :) (this is the second time this has happened to me).

 

Cheers

 

Richard

Edited by RichardSpag
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  • 1 month later...

About the comment above regarding the loss of front-rear brake linking, is that something the Camhead's electronics modulate? My '05 FJR had linked ABS brakes and that was accomplished hydraulically. I believe it was a metered tap off one pair of the front caliper pistons (it's been a while so I'm only dimly aware of how that was set up).

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About the comment above regarding the loss of front-rear brake linking, is that something the Camhead's electronics modulate? My '05 FJR had linked ABS brakes and that was accomplished hydraulically. I believe it was a metered tap off one pair of the front caliper pistons (it's been a while so I'm only dimly aware of how that was set up).

 

Morning Pappy35

 

Yes, it is controlled electronically then implemented hydraulically. (it can't use a direct hydraulic link as it only has one brake line going to each caliper & that line feeds all caliper pistons).

 

The front brake hydraulic input into the ABS controller turns on the rear servo pump motor then the ABS electronics control the rear barking pressure based on front braking input. (rear brake is servo powered when linked & when in ABS mode but not servo powered when using "just" the rear pedal) --the rear brake is not servo powered from rear brake pedal.

 

The rear brake pedal/cylinder is a stand alone that only operates the rear brake (no linking to the front).

 

There is also a learning algorithm in the ABS controller that continually balances front/rear braking. (kind of an electronic proportioning valve)

 

The BMW I-ABS gen2 system is sort of a strange system (or logical system depending on how you view it).

 

 

 

 

 

 

 

 

 

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