Question about 1998 BMW R 1100 RT (ABS)

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I have a 99 R1100RT and the ABS lights keep flashing or once in awhile just stay on and don't flash. It's my understanding they should go out when working right. I have replaced one prox and check the rear prox and it was ok. I have checked and rechecked the air gap, and bled the brakes both with pressure and vacuum with no success.

Posted by Anonymous on

  • Anonymous Oct 10, 2010

    Thanks I will see if I can find the how to on the LED setup then find a flash code to know what it is telling me. Thanks again. Tom



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Amrit sahni

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ABS - Anti-Lock Braking System And EBD -Electronic Brake-force Distribution In Plain English Posted by: Rohit Khurana March 1, 2010 in Automobile Technology
AdvertisementCarBlogIndia Technology Articles , today I will talk of one of the most talked about safety feature called the ABS And EBD. Again I will try to keep the language simple and human understandable (which non-engineers can also make some sense of), pun intended.
What Is ABS ? Anti-Lock braking System system or ABS is a safety system which prevents the wheels on a moving vehicle from locking up(or cease while rotating) while braking. ABS offers improved vehicle control over dry and especially slippery surfaces by reducing the braking distance but it can also increase the braking distance in case of loose surfaces like snow, gravel etc. Ever since the invention of ABS, it has been evolving and the recent systems not only prevent wheel locking but also electronically control the front-to-rear brake bias, which we know as Electronic brake force system, Traction control system, Emergency brake assist or Electronic stability control.
Working Of ABS
When brakes are applied under heavy loads, the braking pressure becomes high resulting in heavy braking or in other words locking up of wheels. The ABS overcomes this by monitoring the wheel speed and releases pressure on each wheel brake lines in the form of rapid pulses switching between different brake lines. which prevent locking-up.

Preventing lock-up under heavy braking helps the driver in maintaining control over the vehicle. In modern ABS an individual brake line is provided for each of the four wheel enabling different braking pressures for different road surfaces of the wheels.
What Is EBD ? Electronic brake- force distribution system also called as Electronic brake-force limitation is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's brakes, based on road conditions, speed, loading, etc.
EBD system is always coupled with anti-lock brake-force system. The most important function of EBD is to maintain vehicular control with variation in braking pressure applied to each wheel in order to maximize stopping power. Generally most of the weight of all vehicles is carried by the front end so the EBD ensures less braking pressure at the rear end to avoid skidding. But in some EBD's the distribution of braking pressure at the rear end is more initially when the brakes are applied before the effects of weight transfer comes into play.
Working of EBD system An EBD is a subsystem of the abs and its function is to control the effective adhesion utilization by the rear wheels. this definition has been given by SAE in its technical paper no. #920646.
The Antilock brake force system releases pressure in different brake lines at the time of heavy braking to prevent locking-up. The action comes in the form of releasing pressure from the braking circuit when it detects extreme and rapid deceleration in any of the four wheels in order to make sure that the driver maintains control over the steering during panic or emergency braking. For example if the wheels of a vehicle are on snow as well as asphalt then in case of emergency braking the ABS will monitor the speeds and eventually the EBD system will release less pressure for wheels on snow and more pressure for wheels on asphalt to prevent wheel lock-up

I have a 99 R1100RT and the ABS lights keep - 99-r1100rt-abs-lights-keep-jserdy1edku5qfscwskpevsm-4-0.jpg

Posted on Jun 24, 2015



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Check for a weak battery. The older ABS systems on BMW motorcycles are very sensitive to battery voltage on startup. Example: If battery is weak, engine is slow to crank over and ABS unit will see low voltage. Run bike for 10-20 minutes (riding, not idling!!) and then turn off ignition (key) Restart bike and if ABS lights go out after pull away test, battery is weak/defective of needs to be charged.

ABS sensor air gap will not have any effect, and nor will quality of brake fluid.

Also, when bleeding brakes, BMW says not to use vacuum systems to pull fluid through system. Apparently, it can damage ABS modulator located under gas tank on your bike.

Posted on Oct 08, 2010

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  • Anonymous Oct 09, 2010

    Brand new battery in May and problem didn't go away.

  • Anonymous Oct 09, 2010

    Ok, battery is usually the culprit.

    Have you tried to read the codes in the ABS controller? The 99 R1100RT should have a small three pin diagnostic connector under the seat. There are several write ups on the internet on how to make a test LED and read out the trouble codes. I would suggest that be the next step.

  • rxmich Jun 17, 2011

    A weak battery will cause this fault. The ABS system requires decent amperage to function. You can usually tell if this is the problem because the lights flash that it is not engaged when after start-up and roll. After 5 minutes of recharging the battery, if you stop then restart and roll the lights go off. I have gone to a stronger battery than the BMW battery to solve this problem. Mine is a 22 AMP hour battery rather than the BMW 20 AMP hour. Not only that but the battery only costs $45.00.

    If the light is staying on all the time and the battery has been replaced then pull both sensors near each brake caliper. These guys DO NOT normally go bad BUT...make sure you clean the heads with a bit of alcohol and a cloth to remove dirt or metallic particles picked up off the road. A bit of metal stuck to the magnet will dramatically change the magnetic field and no usable signal will occur. Re-install and you are ready to ride.

    Bob K

  • Anonymous Jun 17, 2011

    Took to a BMW tec who was busy but took the time to hook to his PC via the connector under the seat and there was no comunication. So I guess there could be a wire issue or as he put it or a bad cpu for the brake system.



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