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Thread: ABSi problem on R1150GS 2004 model

  1. #1
    DLEVQS
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    ABSi problem on R1150GS 2004 model

    A while ago I found the ABS lamp flashing rapidly with the warning lamp - odd times during the ride this would start. I could shut off the bike and it would go away on restart. No problems with any of the brake system were evident. Then the warning lights stayed on longer until they were flashing and lit immediately after startup. I checked all the easy stuff and found nothing.

    "Gen ON, ABS flashes at 4Hz =At least one brake circuit in residual braking function mode."

    This is definitely not the case here as I proved by road testing the brakes.

    As it was time to do it, I replaced all the brake fluid in both front and rear systems including all the ABS modulator bleed valves. After doing this the lights stayed off - for 30 miles. Then they came back on and now stay on all the time.

    There is no sign of frayed wires. The front sensor looks fine. The reservoirs are both full. The battery voltage is excellent and the alternator puts out plenty of current. I replaced the battery about 3 months ago - the old one died basically.

    I have tested the brakes repeatedly under all conditions including several times at 60 MPH. The ABS works perfectly in dirt and gravel.

    To run down the scorecard to date:
    1. Battery voltage is OK
    2. ABS sensor gap measures ok - front and back.
    3. tail light is ok - even with the Hyper Lite only 1/2 lit on 1 side it did not make any difference when I eliminated that totally.
    4. handgrip is definitely clear of the lever for front brake
    5. micro switches both seem to be working - I can hear them when the lever is pulled a small amount
    6. brake pads look to be ample thickness.
    7. fluid is above min in both reservoirs and is new fluid throughout both systems.

    Any other suggestions? Now the lights light up as soon as I turn on the ignition.

    Doug

  2. #2
    Daily Rider jurgen's Avatar
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    Check your owners manual - it has the ABS blinking codes listed. There are a number of different combinations of slow and fast blinks. Easiest problem may be a failed brake light bulb but I see you already checked that. Next is the microswitches - make sure neither hand nor foot lever is touching anything and both levers can freely return to the fully "brake off" position. Do the microswitches activate the brake light? You may hear clicks and they still are defective. Fluid levels in the outside reservoirs are only half the story. There are two more reservoirs in the ABS modulator under the tank.
    Let us know what the exact code is.
    J?rgen
    Red Rocks
    04 R1150GS adv
    04 K1200RS last of the great bricks

  3. #3
    DLEVQS
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    Continuing dillemma ...

    Quote Originally Posted by jurgen View Post
    Check your owners manual - it has the ABS blinking codes listed. There are a number of different combinations of slow and fast blinks. Easiest problem may be a failed brake light bulb but I see you already checked that. Next is the microswitches - make sure neither hand nor foot lever is touching anything and both levers can freely return to the fully "brake off" position. Do the microswitches activate the brake light? You may hear clicks and they still are defective. Fluid levels in the outside reservoirs are only half the story. There are two more reservoirs in the ABS modulator under the tank.
    Let us know what the exact code is.
    Jurgen - apologies to you and any others that follow both this and ADV rider. You responded to my query over there as well as this one here. Anyhow - here is the latest report to be sure we are all together on this epic tour of the GS brake system.

    "Gen ON, ABS flashes at 4Hz =At least one brake circuit in residual braking function mode."

    This is the flashing code I continue to get. This morning I pulled out the 2 ABS sensors and cleaned them. I checked the micro switches - again - very carefully inspecting them and oiling them and checking for debris. They both work (even without ignition on I can hear them). If they just light the brake light, then clearly they are functioning.

    I eliminated the Hyper Lites as on 1 side the unit had 1/2 the LED's lit and 1/2 dead.

    I have changed all the fluid at the ABS modulator - front and back caliper lines, all control circuits and metering circuits, new fluid and bled carefully. Manually sucked out the old fluid from every reservoir and the ABS reservoirs and then bled each bleeder nipple until new fluid came out.

    One suggestion from a fellow GS owner was to Ohm out the ABS sensors to see what the reading is. The ABS system functions with repeated tests on dirt and gravel so I can see little chance of those malfunctioning.

    I still get that pattern of lights as soon as the ignition is turned on.

    Any other thoughts?

    Thanks.

    Doug

  4. #4
    Daily Rider jurgen's Avatar
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    Doug,
    can you narrow it down to which one of the circuits is in residual mode? You should be able to tell by the way either the front or rear brake responds.
    Then you can focus on the circuit that is faulty.
    Also, did you physically disconnect each microswitch to make sure it functions?
    J?rgen
    Red Rocks
    04 R1150GS adv
    04 K1200RS last of the great bricks

  5. #5
    DLEVQS
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    Quote Originally Posted by jurgen View Post
    Doug,
    can you narrow it down to which one of the circuits is in residual mode? You should be able to tell by the way either the front or rear brake responds.
    Then you can focus on the circuit that is faulty.
    Also, did you physically disconnect each microswitch to make sure it functions?
    I don't think either one is in residual mode, Jurgen. At a 60 MPH full lever stop the bike is almost falling over dead in 30'. It is a bit nose-down at that point so I have to say it is possible the rear brake is doing less than it should but then I seldom have done a panic stop at that speed so I cannot be certain.

    No I did not disconnect either microswitch. I can Ohm those out but then disassembling the front lever mechanism looks a bit difficult. The bottom one is a more likely culprit anyhow. That thing looks like it was engineered for failure!

    Thanks for the reply.

    Doug

  6. #6
    Daily Rider jurgen's Avatar
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    Can you try to use only the rear to see if you can get it to lock? That might tell you if the rear circuit is in residual mode. Disconnect the rear switch cable to test the switch. Problem with these switches is that they are normally open and only close as you push the pedal. That means the contacts can oxidize when moisture gets in.
    Next, find a friend who has the GS-911 diagnostic tester. That should tell you more.
    Other than that, I'm at the end of my wits now.
    Hope you get it solved. Good luck
    J?rgen
    Red Rocks
    04 R1150GS adv
    04 K1200RS last of the great bricks

  7. #7
    DLEVQS
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    Quote Originally Posted by jurgen View Post
    Can you try to use only the rear to see if you can get it to lock? That might tell you if the rear circuit is in residual mode. Disconnect the rear switch cable to test the switch. Problem with these switches is that they are normally open and only close as you push the pedal. That means the contacts can oxidize when moisture gets in.
    Next, find a friend who has the GS-911 diagnostic tester. That should tell you more.
    Other than that, I'm at the end of my wits now.
    Hope you get it solved. Good luck
    Jurgen - gaining information here, thanks to your suggestions. I found this AM that the rear brake pedal alone gives poor braking and at 20MPH I had to stomp it hard to get it to lock up the wheel. Clearly the rear circuit is the problem.

    I pulled apart the connector to the rear microswitch and it tests fine - it is NC by the way, but opens instantly when the pedal is depressed even a tiny amount.

    I then rebled all the rear modulator and rear caliper bleed valves. All show nice clean fluid emerging from the waste tube.

    However now the servo does NOT whine when I press the rear brake lever alone. It works fine with the front lever but will not fire when only the rear brake pedal is pushed.

    Any ideas?

    Doug

  8. #8
    Brett
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    Same thing happened to me twice in two years and it was two different problems. First time it was the front ABS sensor $139.00 and the next year it was the rear brake light ABS switch around $400.00 on the road in Utah. Did all the other stuff you did these are the things that solved my problem which sounds exactly like yours. Good Luck BTW mine in a 2004 Gs also and had 85,000 miles
    Last edited by Brettendress; 11-26-2010 at 06:46 PM. Reason: Addition

  9. #9
    DLEVQS
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    Quote Originally Posted by Brettendress View Post
    Same thing happened to me twice in two years and it was two different problems. First time it was the front ABS sensor $139.00 and the next year it was the rear brake light ABS switch around $400.00 on the road in Utah. Did all the other stuff you did these are the things that solved my problem which sounds exactly like yours. Good Luck BTW mine in a 2004 Gs also and had 85,000 miles
    Don't think it is either of these - front brake circuit works fine, Brett. Brake light comes on when either the lever or the brake pedal is depressed.

    It baffles me now why the servo does not come on when the rear brake pedal is depressed.

    The suggestion to buy or borrow a GS911 diagnostic tester leaves me a little skint - $300 for one of those or else search for a kind soul willing to lend one.

    At least now I know it is the rear circuit and is NOT either of the microswitches nor the fluid in the system.

    Any other ideas on why the servo is not working on the rear circuit, or how to test that further?

  10. #10
    Daily Rider jurgen's Avatar
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    Quote Originally Posted by Brettendress View Post
    Same thing happened to me twice in two years and it was two different problems. First time it was the front ABS sensor $139.00 and the next year it was the rear brake light ABS switch around $400.00 on the road in Utah. Did all the other stuff you did these are the things that solved my problem which sounds exactly like yours. Good Luck BTW mine in a 2004 Gs also and had 85,000 miles
    The 4 Hz blinking lights mean that it gets stuck during the POST. Normally the POST lasts about 2 seconds, then the 4 Hz blinking switches to the 1 Hz blinking. That's when the ABS sensors come into play. So Doug's problem is unlikely one of the ABS sensors (at least, IMHO).

    Doug, interesting find that the brake switch is NC. Learned something new - on my "96 R850R it was definitely NO, and NO switches are more vulnerable to contact corrosion.

    Have you traced the signal from the rear brake switch all the way to the ABS unit? That would be my next step, making sure the brake switch signal arrives at the ABS unit. If you can figure out how to bridge the pins, that would be my next test. According to my diagram the switch wires are yellow with black stripes and yellow with green stripes.

    Also, have you function tested and verified both ABS relay and ABS control relays?
    J?rgen
    Red Rocks
    04 R1150GS adv
    04 K1200RS last of the great bricks

  11. #11
    DLEVQS
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    Quote Originally Posted by jurgen View Post
    The 4 Hz blinking lights mean that it gets stuck during the POST. Normally the POST lasts about 2 seconds, then the 4 Hz blinking switches to the 1 Hz blinking. That's when the ABS sensors come into play. So Doug's problem is unlikely one of the ABS sensors (at least, IMHO).

    Doug, interesting find that the brake switch is NC. Learned something new - on my "96 R850R it was definitely NO, and NO switches are more vulnerable to contact corrosion.

    Have you traced the signal from the rear brake switch all the way to the ABS unit? That would be my next step, making sure the brake switch signal arrives at the ABS unit. If you can figure out how to bridge the pins, that would be my next test. According to my diagram the switch wires are yellow with black stripes and yellow with green stripes.

    Also, have you function tested and verified both ABS relay and ABS control relays?
    Jurgen - I am following you. You are talking about the ABS relay in the fuse box and the control relay that sits beside the ABS modulator, correct?

    It could well be that now the rear brake switch signal is not arriving where it needs to get. I will poke around in there next. If there is a connector then I can Ohm out the pins to find the switch from the rear brake pedal for sure. Good suggestion. Thanks.

  12. #12
    DLEVQS
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    Unhappy GS911 readout - fault codes

    I borrowed a GS911 diagnostic device and got the following readout today:

    Faultcodes found
    17914 Faulty power supply to warning lamp relay
    the fault is not present now
    17438 Pressure in rear wheel circuit too high
    the fault is currently present

    Can anybody help me decipher this to figure out what to do next?

    This bike has 20K miles on it. I sure hope the modulator has not crapped out - stuck valve or some such!

    Jurgen, anybody - thoughts?

  13. #13
    Daily Rider jurgen's Avatar
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    Sorry Doug,
    I don't know any solution here. At least, you have isolated the problem. Do you have access to a BMW shop that might have a troubleshooting guide? Also, if you can clear that fault code, does it show up again during the POST or only when you push the brake pedal?
    J?rgen
    Red Rocks
    04 R1150GS adv
    04 K1200RS last of the great bricks

  14. #14
    DLEVQS
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    BMW dealer is a desperate last measure here - long ways away and not responsive by reputation.

    I cleared the fault codes and retested the bike and got the same readout instantly upon starting the ignition. The ABS self-test never runs at all, Jurgen.

    Could this be a breakdown inside the modulator?

    Thanks for getting back to me, Jurgen.
    Last edited by DougVieques; 12-19-2010 at 10:43 AM.

  15. #15
    DLEVQS
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    From the Wisdom section of ADVrider:
    4.13 Other ABS problems

    1200GS
    The Honorable rideLD has, based on years of following GSpot, compiled the following list; his experience is that almost all failures are one of these six.

    6 things to cause ABS failure.

    1- Lever or pedal failing to travel fully back to the correct position. This is usually caused by the hand guard preventing the front brake lever from fully extending or a pebble or twig preventing the brake pedal from returning to its up most position. An easy way to tell that this is your problem is if your brake light is always be on. Notice, however, that it is possible to pull the lever sufficent for the ABS system to detect it, but not enough for the light to come on. This can be a confusing situation.

    2- Sensors. If either of your brake sensors fail the brake light will stay on. Severed wires, dirty sensors or melted sensors can cause this failure. If your speedo works then your rear sensor is definitely OK. Make sure your front sensor is clean and wire is not severed.

    3- Fluid levels. Tip overs can cause fluid to leak out of the ABS pump under the gas tank. Pull off the gas tank and top off each of the circuits. This will fix a fluid level related failure.

    4 - Microswitch problems. There is a little tiny switch under the front brake lever and next to the rear brake pedal. You should hear an audible click when you activate either. This switch can fail although it is rare. If your problem is not 1,2 or 3 then this is probably your problem. If the switch is bad your brake light will not activate from the bad switch.

    5- Low battery voltage. This is a the common cause of ABS failure on the 11xx versions of ABS. Usually the ABS will start working normally when the alternator gets the charge back up to normal. The ABS versions on the R1200GS are not as senstive to low voltage issues and voltage related failures are very rare.

    6- Bad pump unit. Very rare. In fact I have not heard of one failing on the R1200GS yet. There have been a few replaced but these were diagnoses errors and real problem was one of the four items above.

    I have eliminated numbers 1-5. What is left? Now, this is applicable to the R1200GS but mine is probably not much different. Am I reading this wrong?

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