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Thread: 2002 R1150RT brake failure

  1. #1
    Registered User thompsonr's Avatar
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    2002 R1150RT brake failure

    I have a 2002 R1150RT with 68K linked brakes servo assisted . Last week I had a brake failure light appear and loss of my power assisted brakes. Brake failure light flashing fast 4Hz and general warning light on. I bought a new battery as I knew mine was getting weak. Failure light came on again in just a few miles.

    I have read every thing I could here and elsewhere on the web and decided the next thing to do would be to bleed the system. With system bleed today including the servo unit it looked for a while like we might have fixed the problem then the failure light again.

    Now when the light come on fast 4Hz brake failure light and general warning light. When I pull the front brake lever it does not activate the servo when I push the brake pedal it activates the servo which stays on (run the servo) even when released.

    This is intermittent shutting the key off resets the system and brakes function normal with front brake lever activating servo and rear pedal activating servo. then after some time and multiple uses the failure light will come back on.

    Need some guidance here whats this sound like and what should I try next.

    Hope I have explained this so it understandable

    thanks Rick .
    R and R

  2. #2
    MOA #24991 Pauls1150's Avatar
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    The slow (4 Hz) flash plus the Gen(erator) light indicate "at least one brake circuit in Residual braking mode".

    First check might be the front brake switch - When you apply the front brake, does the stoplight in the tail light up? If not, that could point to a bad switch there or bad wiring, or worst case, a computer problem, since the switch goes directly to pins 39 & 40 of the computer connector.

    If the stoplight does come on when squeezing the front, that should bless the wiring & the input side of the computer; next step might be to do a "master reset" of the computer by pulling Fuses #1 (ABS) and #5 (Motronic) for a few minutes (so internal capacitors can discharge), reinstalling them, & try again.

    Note also that a weak bulb, or worn or corroded contacts in the socket, will also have the computer telling you "something" is amiss, so check that socket & give it a new bulb anyway. But that wouldn't ("shouldn't") cause a loss of the ABS.

    Also make sure that the "new" battery really is Fully charged - like at least full day or two on the trickle charger. The ABS is sensitive to low voltage, and you have no idea how long it was sitting on the dealer's shelf before you bought it.

  3. #3
    Registered User thompsonr's Avatar
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    Thanks

    When in failure mode the brake light comes on when the front brake is applied. I haven't changed the bulb but did clean the contact of the bulb and checked for corrosion in the socket. I will replace bulb.

    The battery checks at 12.80 volts with key off drops to lower 12s when key is on lower 13s running. there is no drop of amperage when in the fail mode.

    Will try the master reset. I will assume the bike needs to be running? does it need to be in the fail mode or can this be done any time?

    Thanks for the reply.

    Rick
    R and R

  4. #4
    MOA #24991 Pauls1150's Avatar
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    The reset can be done anytime; key off.

    (Corrected!)

    And you may need to do the "slow throttle twist" afterward (key on but engine not running) to re-teach the computer the TPS voltages.

  5. #5
    Happily Bent dieselyoda's Avatar
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    Quote Originally Posted by Pauls1150 View Post
    Note also that a weak bulb, or worn or corroded contacts in the socket, will also have the computer telling you "something" is amiss, so check that socket & give it a new bulb anyway. But that wouldn't ("shouldn't") cause a loss of the ABS.
    Pauls1150 is absolutely right. A bad bulb "shouldn't" cause an ABS fault but in my experience, a bad bulb will cause an ABS fault. It's the very first thing I change, then I reset the ABS and in almost every situation I have had with my friends' bikes, Beemers or others, the problem was solved.

    I can't explain it with a sound response that makes sense.

    My Chev truck had the ABS light come on when my girlfriend took it this morning. My center brake bulb was burnt out. I changed it, ABS working again. After reading the posts here, I scanned it and got a wheel sensor fault in history. Cleared the fault, took it for a drive, fault gone.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  6. #6
    Registered User thompsonr's Avatar
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    Thanks picked up a new bulb today but as I said this is now intermittent making things worse. the failure light hasn't been on since yesterday .Had planned to ride today as temps are great but we have a 30+ mph west wind. Not a good day for riding.

    The power assisted brakes are awesome when they work but in fail mode they are scary bad about half of what average braking power of a non assisted bike. Worst of all I don't know what I am going to get the next time I hit the brakes.

    Thanks Rick
    R and R

  7. #7
    MOA #24991 Pauls1150's Avatar
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    Scary is an understatement... Be prepared to downshift quickly!

    They've improved the system since then, but yeah, "residual braking" is a diplomatic euphemism!

    One more relevant "battery check" -
    On the centerstand (preferably with a friend to hold it) and the engine at about 2500 rpm (so the alternator is supplying), put a DVM on the battery (or other convenient points) and clamp hard on the brakes - see what the voltage drop is then. I don't know what's typical, but the ABS and the "power booster" pull some serious current too.

  8. #8
    Registered User thompsonr's Avatar
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    Thanks

    I will try that .Thanks Paul

    Rick
    R and R

  9. #9
    Pepperfool GSAddict's Avatar
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    Question: Are your brake lines the old rubber type or are they SS braid over Teflon?
    '
    Ufda happens..........

    It's all about the details.

  10. #10
    Registered User thompsonr's Avatar
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    lines

    They appear to be the rubber type. I think stock ones that came with the bike.

    R
    R and R

  11. #11
    Pepperfool GSAddict's Avatar
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    Quote Originally Posted by THOMPSONR View Post
    They appear to be the rubber type. I think stock ones that came with the bike.

    R
    Many documented failures with the rubber lines.
    They deteriorate inside and particles block ports and fluid from returning from the calipers.
    This can and has caused ABS failure codes.
    In one case I remember 2 ABS units were replaced before it was determined that there was a blockage in the rear rubber brake line.
    I would suggest you replace with Spiegler SS Teflon brake lines. This should be done in any event as the other way the rubber lines fail is they will bulge/rupture with no warning upon brake application.
    Flush and bleed thoroughly with fresh DOT4.
    This issue is not just limited to 1100/1150s, lots of F650's and K's of that vintage have the same issues.
    '
    Ufda happens..........

    It's all about the details.

  12. #12
    Registered User thompsonr's Avatar
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    Thanks GS I'll look into replacing the lines. Makes sense lots of pressure behind that servo. Definitely an upgrade.

    R
    R and R

  13. #13
    Happily Bent dieselyoda's Avatar
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    I don't mean to be a smartass, really, honestly.

    Quote Originally Posted by GSAddict View Post
    Many documented failures with the rubber lines.
    They deteriorate inside and particles block ports and fluid from returning from the calipers.
    This can and has caused ABS failure codes.
    In one case I remember 2 ABS units were replaced before it was determined that there was a blockage in the rear rubber brake line.
    I would suggest you replace with Spiegler SS Teflon brake lines. This should be done in any event as the other way the rubber lines fail is they will bulge/rupture with no warning upon brake application.
    Flush and bleed thoroughly with fresh DOT4.
    This issue is not just limited to 1100/1150s, lots of F650's and K's of that vintage have the same issues.
    Tons of comments here about bleeding routinely, Teflon brake lines, procedures. I haven't read a comment on these forums unique to Beemers.

    How on earth do you replace ONE ABS unit unless you know EXACTLY why you are spending that kind of money?

    I had a boss once that asked me how sure I was about any given problem. One time, I had an engine that kept blowing up the fuel pump drive. On that engine, it had a jack shaft for the pump drive. $1200.00 for the shaft and about $1200.00 in labor to replace. He asked me how sure I was and I replied 99%. He told me, "Go ahead, if you're wrong and it's the 1%, it comes out of your paycheck because I can't ask the customer to pay for your gambling."

    5 hours of my own time, we called it community service, drive gear end bearing was done. $10.00 in parts, 20 minutes of labor and my Christmas bonus that year was half my salary. We kept our customers.

    I'm going to keep repeating this over and over. Start simple, fix what you know, if that doesn't work, start from the beginning again. Sometimes it really sucks. I got stories just from today!
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  14. #14
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    I just replaced my lines. It was pretty easy. Lots of steps, but none of them were hard or uncooperative. Nothing stuck, nothing tried to round off or strip, bleeding was very easy. The line from the handlebar master cylinder, i used many short pumps, until I quit getting bubbles out the MC, the new line was full and I got only a few bubbles from the ABS bleeders. I put on new front shoes at the same time, I took the calipers off the front for a good cleaning, so I turned them upside down for a very good drain. Bleeding with the pump in there and the beemerboneyard ministan tool is the easiest thing ever.

    Rod

  15. #15
    Registered User thompsonr's Avatar
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    Thanks for the comments. Diesel I appreciate all the advise I have gotten from fellow riders here. And although the advice I have received isnt BMW specific their suggestions might fix my problem and I might be able to do it myself and not spend my Christmas bonus at my local dealer ( a public service employee I have never received a Bonus). Honestly besides the Servo is there any thing any different than any other Mc.

    My hope is this is something besides the servo. I am not a mechanic so anything I try will be simple. I know enough to not get in over my head. I dont want to take it to BMW and have them say yea we changed the tail light bulb that was your problem $$$.

    Paul's suggestion of resetting the computer never though of that.

    Diesel I appreciate your suggestions and all the help I have gotten here.

    Thanks All

    Rick
    R and R

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