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Help!!!! ABS Fault warning light


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Well I was so proud of myself having finished a full tune up on the 04RT. Did all of the fluids,filters including the gas filter, alternator belt, Ohlin rebuild, valve check and TBS.


Then I did the brakes......yes I followed all of the prescribed procedures (thanks Jamie, Leslie and others). I did the wheel circuits and control circuits front and rear and didn't encounter any problems other than sucking air into the front wheel circuit when the funnel ran dry while my attention was focused elsewhere. I ran a ton of Dot 4 thru the circuit and got all the bubbles out. When I did the control circuits I disconnected the ABS electrical connector so I could easily access the 6 bleed screws. I splashed a little Dot 4 on the pins when pulling off the tubing from the bleed screw but I went to great pains to clean up the connector and pins..... So cutting to the chase, when I put it all back together and took her out for a spin the triangle ! warning light came on and stayed on.

The brakes work perfectly fine.


I tried turning the engine off and on while riding down the road but that did not reset the apparent fault and the light stayed on.


At this point I'd gassed up and had a full tank of gas so I took the bike on a 250 mile spin up the coast to see what might happen and to burn off the gas so I could remove the tank more easily and start over.


I re-did the entire wheel and control circuit bleed process this afternoon and rechecked and re-cleaned the ABS connector. Made sure all the reservoir levels were topped off in the ABS module and the hand and foot brake reservoirs.


Took her out for a spin and CRAP! Warning light still on.

I've read that the 04RT ABS module will automatically reset itself so it isn't necessary to do a fault reset like on some models. I don't know if this is correct or not.


I'm out of ideas, the bike runs great and the brakes are like new now. There is nothing wrong with the brakes!!! Except that blasted light is staring at me and won't stop.

I tried putting a piece of black tape over the light and that worked for a while... I knew it was still there and glaring at me under that tape! These are the actions of a desperate man!


HELP Please! :dopeslap:



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Do not worry so much :)


I bleed the same brakes on a r1150 rockster and got the same thing. So, just like you, I re-bleed them again. The results was the same. Most importantly, the issue was intermittent. Once, the owner of the bike reported that he had almost no brakes, like the servo was not working and you know what kind of brakes you have in that case.


The issue was the battery. As soon as we got another battery, it all started to work OK.



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If the triangle (GENERAL WARNING LIGHT) is on and the ABS warning light is off that means brake light failure. Page 71 of Rider's manual.
Or tail-light failure. The ABS controller operated both lamps, so it can use the non-failed light as a sunstitute for the failed one.



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Morning Barry


A mentioned above the General warning light being ON but the ABS light being OFF usually means the rear tail light circuit has an issue.


As a rule that means a burnt out tail light bulb. Both the tail light & brake light are controlled by the ABS controller. So IF the ABS controller sees a resistance change in the tail light circuit it brings the brake light on at partial brightness to act as the tail light then illuminates the dash general warning light.


First thing is -- check your brake/taillight bulbs. Actually remove the bulb & visually check the filament. Just because you have a tail light showing isn't enough.


Next-- if the tail/brake light bulb is OK then look inside that ABS controller connector you removed & re-installed. It's possible you bent or pushed one of the terminal pins back out of place so now it isn't making good contact.


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Or tail-light failure. The ABS controller operated both lamps, so it can use the non-failed light as a sunstitute for the failed one.




Only the brake light bulb will substitute for the tail light bulb. If the brake light bulb blows, you don't have a brake light at all. You will get a warning on the dash.

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Hmmmm... I didn't realize the ABS controller was smart enough to substitute brake light for tail light when there was a failure of the tail light. I had already checked to see that I had brake lights so now I'll actually inspect the bulbs and see if that could be the problem.


It does seem peculiar that the fault would occur coincidentally with the ABS service. Why would that cause a bulb failure? Anyway I'll be checking the bulbs later today and hope that is the problem. Thanks guys.

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Afternoon Barry


From the BMW operational overview on the 1150 I-ABS system--


" BMW Integral ABS also offers some other new safety functions. One example is the constant monitoring of the tail and brake lights, as well as the telltale automatically informing the rider of any defects. Should the tail light fail to operate, in turn, its function will be taken over by the brake light dimmed to a lower level. An additional telltale in the cockpit also warns the driver should brake fluid in one of the two brake circuits drop below a critical point."


Added: If you can't find a bad rear bulb filament maybe try using a 12v test light to see if you have power to the tail light socket. If not then suspect a problem in the connector at the ABS controller (like a bent or displaced terminal pin).

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"Happy is the man who finds wisdom" (Proverbs 3:13)


It was a burned out tail light that was causing the fault light just as you guys predicted. I replaced all 4 rear light assembly bulbs (they were 10 years old so I got my $$ worth)


Now I feel kind of embarrassed but I'll get over it and maybe someone else will learn from my laziness/stupidity.

I mean it is all right there in the owners manual even the part about the brake light taking over when the tail light burns out. I just was too lazy to read it that thoroughly and ended up going to a lot of unnecessary work and agitation. So live and learn!


Thanks so much to all of you for getting me on the right track to resolving this ABS fault issue. It was a $2 fix and that is a lot cheaper than going into my local dealer for a diagnosis and repair. You are the best!

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