Brake Failure Light

[celticus]

Are there any new thoughts on this? Once this weekend at a rally the brake failure light was blinking and I stopped the bike and restarted and all was cool and rode for a day and a half then this morning the light came on solid non blinking. The brakes work fine and the brake light bulb is good.
This morning I DID start out by going down a very steep gravel driveway.
I have charged the battery and restarted the bike but the light is still there.

Mark

[gibbo111]

Try putting a new light globe in

[celticus]

Is a light globe like a light bulb?

Mark

[AlecMyrddyn]

Double check the bulb. The computer can sense when one filament is out, and can make the bulb look like it's working okay when in reality it has a burnt out filament.

-Alec

[celticus]

I hit the brakes while the bulb was out of the red lense and both filaments are working.

Mark

[mogu83]

i think it explains in the owners manual what happens when one of the filaments in the tail light goes out. The bike fakes it to look like the bulb still works. It's been covered on this list a bunch of times.

Best course of action for you (IMHO) is to spend $2 for a new bulb (globe) and see if that cures your problem.

[hjsbmw]

If it's not the bulb I'd check error codes and, unless you have a terminal abs fault, flush the brakes.

[Lost Rider]

You can try cleaning the ABS sensor on the front wheel, in the past when I got the dash BRAKE light that solved the problem. Usually that was after riding many miles on gravel/dirt though. It's happened a few times to me.

The fact that you reset the system and the light went away at first would lead me to believe it has something to do with the ABS. I don't think it has anything to do with your tail brake lamp, and I don't believe there's any sensor in the system where changing the brake fluid would help either.
I could be wrong but I believe that BRAKE failure warning light is just talking about the ABS system not any lamps, so somewhere you have a loose cable, dirty or bad sensor, or a problem with the ABS system itself.

I'm not a BMW mechanic, but I did stay at a Holiday Inn last night.
That's my best internet diagnostics based on my limited knowledge but experience with the 12R ABS system, when it comes to brakes and ABS if the light does't go away after checking the easy things I mentioned I would seek professional help, since with no ABS your linked braking is also not working correctly, and that's not cool. Probably why on a GS when the ABS fails it just has an ABS light, you still have normal braking without ABS, where as on the R with linked brakes when the ABS/linked brakes fails it's considered a BRAKE FAILURE....

[celticus]

Thanks Joe I'll give it a try. I WAS on gravel roads for a number of miles this weekend.

Mark

[Lost Rider]

Right on, there's also a plug under the seat and under the tank to check too coming from the sensors to check if a simple cleaning of the sensor doesn't fix it. Easy to follow the sensor wire to track them down and give them a squirt of electrical contact cleaner.

Would these gravel roads happen to have be with washboards? I experienced my ABS failing just from being on miles of washboards too, after getting off the washboards and a cycling of the ignition the system the warning went away without cleaning anything.

This would be one of those times:

[hjsbmw]

I don't believe there's any sensor in the system where changing the brake fluid would help either...

The ABS unit tracks internal pressures in the front and rear circuit, which can be 'implausible' when there are too many contaminants in the brake fluid. There are related fault codes which eventually trigger the brake failure light. Just keep that in mind if trying the other suggestions doesn't get rid of the warning.

[Lost Rider]

Interesting, I didn't know that, obviously. Thanks for sharing. So you're saying it won't register pressure in the sensors if it's too dirty?
My rear brake fluid is long overdue for a change and is black.... I wonder how dirty it has to be, if that's the case?

[hjsbmw]

Interesting, I didn't know that, obviously. Thanks for sharing. So you're saying it won't register pressure in the sensors if it's too dirty?
My rear brake fluid is long overdue for a change and is black.... I wonder how dirty it has to be, if that's the case?

I don't know if it's dirt or water that causes problems, but I imagine either could lead to it. It will register a pressure that does not make sense to it, not no pressure. The fault says something like 'implausible pressure in front/rear circuit', in case you have a gs-911. I can only speculate that either dirt clogs something or the water lowers the boiling point and with it the pressure. I had the light come on once and that fault was stored. I flushed the system, and it didn't reappear. That was several thousand miles ago. The fluid at the time was brownish.

[celticus]

It has been several thousand miles since I flushed the brakes.

Mark

[deilenberger]

It has been several thousand miles since I flushed the brakes.

Mark

I wouldn't worry about miles - it's time based. The fluid doesn't wear out, it gets full of moisture.. and that's strictly a time based thing (and probably where you live.. Pacific NorthWet would probably be quicker then Arizona or Nevada.)

BMW spec's every 24 months - starting with the date the bike was manufacturered (not the date it went "in-service"..) and looking at my fluid when I do it, I think that's a fairly safe interval.

[celticus]

Guys, I flushed the brake fluid today (love those speed bleeders, thanks Don ) and it did not fix the brake failure light problem.
Turns out it’s not just the light, my ABS is really NOT working. I found out in the gravel that doubles as my driveway.
I changed the rear brake light bulb. Also just for the heck of it I disconnected the battery to see if I could reset something but to no avail.
Thinking back I HAVE let my 3.5 year old battery go WAY dead (6 or 8 volts ) several times. It still starts the bike without any hint of hesitation but I have heard that a somewhat weak battery can cause ABS problems.
I have a good meter does anyone have a suggestion for a starting /load test?
Brake light bulb changed.
Brake fluid flushed.
Both brakes work fine. Non ABS
Any suggestion appreciated.
I guess I should also ask about battery recommendations.

Mark

[Bob Ain't Stoppin']

Mark, If your meter has a peak hold feature, you can check the max current draw on startup. This gives an idea of the condition of the starter system. The abs will set a fault if the voltage dips too low on start up. With the 1100 series it was 9. something volts. Not sure about today's number on this. But you should be trying another battery or perhaps jumper cables to insure full voltage start to see if that eliminates the fault. I'm assuming here that your fault comes up right at start up. If it comes on later, then you have something else going on.

[hjsbmw]

I have also heard that a weak battery can cause the ABS to not initialize properly. However, it seems your best bet would be to get a fault code readout.

[celticus]

I checked the voltage at the battery and the results were.
Key off 12.55 v
Minimum voltage during starting 10.5 (this is as best as I can tell) my Fluke meter does min and max voltages but I couldn’t figure it out.
Voltage while running 14.22
Mark

[Bob Ain't Stoppin']

Mark, Looks like your charging system and battery are in good shape. This as long as the startup felt strong during the test. It's that minimum voltage that can get you, so it would be good to learn how to use the meter for that reading.

Now you need to read the faults. Anyone near you have that 911 code reader?