ABS warning light

Greetings. My bike is a 2002 r1150rs. I took out my bike for the first time this year, and got the ABS fault code of steady warning on the general fault light and steady flashing of the ABS light. My battery is 3 years old and is kept on a charger during sit time. I have searched and really haven't found much information about my particular bike. First of all, I'm confused about which ABS system I have. I went for a short ride with the lights flashing and the brakes seemed to work fine. I didn't check the ABS function, but the servos were working fine. I had the brake system flushed at the dealer 2 years ago. I checked the brake fluid levels and both were fine. Any ideas?
TIA, Mark

You said you checked the brake fluid level and BOTH were fine. There are four places to check the brake fluid level. The two master cylinders and two at the servo.

no i didn't dig into that yet. I'll start on that tomorrow

The below is from my 2004 RT owners manual. Yours should be the same.

It sounds like at least one of the ABS circuits is inoperable, but the servo assist is still functioning. I don't believe brake fluid level should give the warning lights indicated. I'm pretty sure they both would be flashing if that were the issue. I'd start with the sensors, looking at wiring, cleanliness and the gap before thinking of pulling the tank. Once the problem is solved, the fault should be stored, but the lights should reset on each startup and rolling ABS initialization. Low voltage or a sticking switch might also be able to cause the issue, but I haven't read exactly which light sequence they would generate.
From http://www.largiader.com/abs/absfault.html:
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iABS fault codes

These should be listed on a sticker supplied with the bike or a table in the Rider's Manual.

Gen OFF, ABS ON = Only residual braking in both circuits.
Gen OFF, ABS flashes at 1Hz = ABS not available. Pull-away test not completed.
Gen OFF, ABS flashes at 4Hz = Only residual braking function available in both circuits. Self-diagnosis not completed.
Gen ON, ABS off = Tail light/brake light defective.
Gen ON, ABS flashes at 1 Hz = At least one brake circuit without ABS.
Gen ON, ABS flashes at 4Hz =At least one brake circuit in residual braking function mode.
Gen AND ABS flashing alternately at 1Hz = Fluid level in Integral ABS too low.
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In dealing with this, it would be a good time to switch to braided stainless brake lines and bleed the clutch as well.

If you have a sticking brake switch you will get the fault for Self-diagnosis not complete which is General Light Off and ABS light flashing 4hz.

Thanks for the tips guys. I'm going to start by pulling the wheel sensors and check the connections making sure they aren't corroded. I do have servo assist on back and front.

Well, I found what I'm sure is the problem. While checking the sensors at the wheel, I found that the wire had been severed somehow. I'm very happy with my discovery! Thanks again for the help.
Mark

ABS/Servpro assist brake failure

Hi this is my first time posting. I am a fairly new rider, just bought a 2004 R1150 RT 1 year ago 17,000 K.

Just to give you a little background just in case some of this may be related.

When I first bought the bike it became quickly apparent the battery was crap. I had BMW replace it with their stock battery as well as check the bike out, everything seemed to be fine no problems.
I decided to add some LED lighting to the brake and tail lights as well as front and rear turn signal’s. I replaced the incandescent bulbs with LED bulbs.

At first everything worked fine, but then as I was taking a road trip the general warning light came on solid. Not long after that was followed with the brake failure
Light flashing fast, I guess I’m learning that was probably at 4 Hz.
I immediately noticed that the brakes were not functioning properly, the ABS/servo assist shut down leaving me with manual front and rear brakes that were very sluggish by the way.

It was suggested to go back to the incandescent bulbs because the lower voltage LEDs may have been confusing the computer/circuit board and in tern giving me all sorts of electrical warning lights and problems.
I got rid of the LEDs replaced them with incandescents.
It seemed to help the warning lights stop flashing and the ABS brakes were working normally.
That lasted for a day or two.
I eventually got the bike to a BMW specialist Who put everything back to normal with the proper bulbs cleared the codes in the system and I was good to go.
The RT was fine for I’d say 2 to 4 weeks and then I started getting the warning light triangle brake warning flashing again with the servo assist not functioning of course.

At this point pretty much getting into the winter had the bike stored for three months or so.
Just started using it again with the same problem.

My friend suggested I replace the BMW battery with an Odyssey pc680. We were hoping the higher grade battery may help to solve some of these electrical problems with the extra voltage and higher performance.

No such luck…
Still getting same problem intermittently. (some days the bike works perfectly with no warning lights, no brake problems)

I do have to mention prior to replacing the battery, we did have the RT connected to the GS 911 diagnostic, It did come back with code saying “front brake switch”
Not sure what that part is and if that may be the problem or not.

I also noticed that when the warning light is flashing and I lose servo assist. When I squeeze the front brake the rear brake tail light does not function or engage. (The brake light did work when I stepped on the break pedal)
when the brake failure light is not flashing with no warning lights the brake lights work fine.

There is been some talk of rebuilding or replacing the ABS pump, but that is very expensive that would seem to be the last resort if all else fails. Any help or suggestions would be greatly appreciated.

Thanks, Greg