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IABS issues R1200RT


mrtg

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Hi

I'm new to forum and wonder if anyone might be able to help me, I have a 2005 r1200rt with an abs issue, the original fault was the abs releasing under heavy braking (the wheels weren't locking) and the brake fault light flashing after. Since then I've totally flushed and bled the system (all 4 circuits) just test rode it, bike seems ok until you apply very heavy braking on rear circuit then fault light comes on and servo stops whining (rear circuit only) front seems fine. Bike resets when power turned off, seems ok until heavy braking re-applied to rear.

I've invested in an elm327 reader and motoscan software, however fault code given means nothing to me (wheel circuit rear code 618c) anyone any ideas, suggestions?

 

 

Thanks in advance Tony

 

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Hi

I'm new to forum and wonder if anyone might be able to help me, I have a 2005 r1200rt with an abs issue, the original fault was the abs releasing under heavy braking (the wheels weren't locking) and the brake fault light flashing after. Since then I've totally flushed and bled the system (all 4 circuits) just test rode it, bike seems ok until you apply very heavy braking on rear circuit then fault light comes on and servo stops whining (rear circuit only) front seems fine. Bike resets when power turned off, seems ok until heavy braking re-applied to rear.

I've invested in an elm327 reader and motoscan software, however fault code given means nothing to me (wheel circuit rear code 618c) anyone any ideas, suggestions?

 

 

Thanks in advance Tony

 

Afternoon Tony

 

A couple of things come to mind--

 

If you were also using the front brake hard then at times the ABS system will release some braking if the ABS system thinks the rear wheel is lifting due to uneven front/rear spin down rates. (there is a built in rear wheel anti-lift algorithm built in)

The ABS light coming on with this isn't normal though.

 

That code 618c is not a normal BMW ABS code (at least one that I have ever encountered) so it sounds like it might be specific to the software that you are using). Grabbing the stored brake code(s) with a GS-911 would probably give a more useful code (possibly anyhow).

 

In any case there are a few thing that can cause your problem--

 

The BMW I-ABS system has a somewhat long standing problem with internal pressure sensors (those sensors are-not, or in the past were-not-anyhow, available so if a sensor problem then possibly Module Masters can help out as they are working on sourcing replacements. (A GS-911 on the system might show a sensor failure).

 

Are you SURE that you have all the air out of the rear wheel circuit? If the rear wheel side circuit has any air in it then that can drive a problem after hard barking due to internal pressure vs apply piston displacement. (given the problem stated this is where I would start anyhow).

 

Another possibility is a rear wheel speed sensor acting up under hard braking due to worn final drive bearing (or spool) movement or defection, or even lots of debris on the rear wheel speed sensor . If the rear wheel speed isn't reported correctly it can drive early rear brake release & even a warning light. (might try removing & cleaning the rear wheel speed senor).

 

Also make sure that the rear wheel speed sensor pig tail isn't pulling tight under hard braking & causing an open.

 

Same with the front speed sensor pig tail- make darn sure that it isn't now (or has been in the past ) rubbing on the L/H front brake rotor.

 

You might also have someone follow you at a distance & see if your rear brake light comes on & stays on even when the problem is happening (if rear brake pedal brake switch is acting up during hard braking that can trick the ABS into a problem)

 

If you can get a GS-911 failure code or verify if that code 618c is a real BMW code then we might be able to guide you more (or possibly call Module Masters & talk to them as they have seen & dealt with a LOT more BMW 1200 I-ABS codes/problems than I have & at times they are very helpful)

 

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Hi

I'm new to forum and wonder if anyone might be able to help me, I have a 2005 r1200rt with an abs issue, the original fault was the abs releasing under heavy braking (the wheels weren't locking) and the brake fault light flashing after. Since then I've totally flushed and bled the system (all 4 circuits) just test rode it, bike seems ok until you apply very heavy braking on rear circuit then fault light comes on and servo stops whining (rear circuit only) front seems fine. Bike resets when power turned off, seems ok until heavy braking re-applied to rear.

I've invested in an elm327 reader and motoscan software, however fault code given means nothing to me (wheel circuit rear code 618c) anyone any ideas, suggestions?

 

 

Thanks in advance Tony

As I recall, there are 10 circuits to the IABS. There are 6 (or 7) circuits on the IABS unit itself, under the gas tank.

It sounds like you are trying to get the front wheel to lock up?!!? I don't think I've ever been able to do that on my '06. Of course, I haven't tried all THAT hard tho either. I can fairly easily make the rear ABS activate with just the front brake handle squeeze.

Trying to get the rear to lock up with just the rear brake is a bit of work too.

Seems to me if it was a rear ABS sensor on the wheel, you would get an error on the dash after "rolling take off" test (I think that's what it's called).

Follow DR's advice above. He is the most knowledgeable for sure.

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  • 3 weeks later...

Hi there

 

Have worked through responses, have bled rear circuits both control and wheel until I'm certain no air is present, checked gaps and clearances, cables etc can't find anything untoward. Took bike for another test ride, deliberately didn't try to activate abs, after 30 mins of riding stopped at T junction holding bike on rear brake, as I pulled away noticed 4hz flashing brake failure light and red warning triangle on. I've contacted motoscan about the fault code that's appeared again (rear brake circuit 618c) there response was they have no further information and to contact BMW, loads of help, would suggest others maybe think twice about this software as the support so far has left me cold.

Anyway upshot is I'm thinking of removing the iABS, happy with how this is done, direct link brakes and remove ecu from abs and reconnect electrics, my question is what's the latest and best way of stopping brake failure light and red warning triangle illuminating, my bikes an RT with canbus, so if anyone's aware of a better method than masking the indication would appreciate it.

 

Thanks Tony

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Hi there

 

I've contacted motoscan about the fault code that's appeared again (rear brake circuit 618c) there response was they have no further information and to contact BMW, loads of help, would suggest others maybe think twice about this software as the support so far has left me cold.

 

Tony - I'm sorry you're having issues! A GS911 is the scan tool you need for BMW Bikes. Motoscan, etc just aren't equipped for the BMW specific info. Maybe someone around you has one? You might check with your local riders club?

 

Best of luck!

 

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  • 4 weeks later...

Managed to get my hands on a gs911, it reported the following fault

24972: pressure in rear wheel circuit to high

I've flushed and bled the bike twice now but still getting the above fault after about 20 mins of riding even when using the rear brake normally, I'm thinking now of removing the abs and putting the bike back to standard brakes

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Managed to get my hands on a gs911, it reported the following fault

24972: pressure in rear wheel circuit to high

I've flushed and bled the bike twice now but still getting the above fault after about 20 mins of riding even when using the rear brake normally, I'm thinking now of removing the abs and putting the bike back to standard brakes

 

Morning Mrtg

 

First, verify that the rear brake master cylinder isn't trapping pressure after a few applies (ie make sure that the rear pedal adjustment hasn't been messed with & that the piston in the rear master cylinder is in fact FULLY returning all the way out).

 

You might even try riding the bike without using the rear brake AT ALL. If problem still occurs then the problem is most likely an internal pressure sensor.

 

Removing the ABS system is an option you will just have to account for the speedometer operation & that pesky dash light.

 

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  • 3 months later...

Decided to take the plunge and remove the system following lots of guidance available online, purchased necessary parts from motorworks (in the uk), re-used some parts of the original iABS metal work to make a good job of sealing the electrics and also providing an original mounting bolt and mount. High density foam sorted warning lights, so still have the amber warning triangle available for low fuel etc. Bike fine to ride and passed MOT with no issues, brakes still very good and I feel safer knowing that they’re there when I need them. Informed insurance company and they had no issues with mod.

To anyone else with same issue, it’s a big job but certainly not impossible and sooooo much safer.

Regards
Tony

PS borrowed a 911 and the fault code shown up earlier by non 911 unit, equated to a rear circuit failure in the iABS unit

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Morning Tony

 

Thanks for the  update,  glad you have it working. -- The I-ABS removal on the 1200RT (is) a real pain (if done correctly)  but does yield good feeling smooth modulating brakes.

 

Can you provide a little more info on how you handled the dash light problem?

 

 

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Hi, I stripped down the dash and using some black high density foam and glue, I blanked off the brake failure led indicator, the warning triangle has two leds one yellow and one red, you blank off the bottom one I think (red) this means your left with the amber warning triangle for low fuel warning etc.

 

hope that helps anyone else with same issue

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22 minutes ago, mrtg said:

Hi, I stripped down the dash and using some black high density foam and glue, I blanked off the brake failure led indicator, the warning triangle has two leds one yellow and one red, you blank off the bottom one I think (red) this means your left with the amber warning triangle for low fuel warning etc.

 

hope that helps anyone else with same issue

 

Afternoon Tony

 

Thanks, I though that might have been what you did but was hoping that you might have found a unique  way to mask them electronically. So far your present way seems to be the normal practice of masking the lights. 

 

Losing the red brake warning light is no big deal but the red general warning light would be nice to retain as it indicates an impending immediate stop-riding event like loss of oil pressure, or loss of battery charging.  

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