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Brake warning light and ! lights flashing rapidly

Lee mentions a good point, and that reminds me of another potential failure point—but one that I doubt is a factor on the bike in question. The fluid level sensors on that reservoir can go bad and read “low fluid” regardless of the actual level. Not available separately, the fix is replacing the complete reservoir.

But that fault usually throws the two brake failure lights flashing alternately at 1k and throws a “fluid low” code.

Best,
DeVern
 
Took off the front wheel and calipers. Noticed that one piston is not moving out. Tested with brake pads removed and one of the four is not moving out. Could this be the culprit?
 
My bad.
I had taken for granted the 2004 R bike had the same rear reservoir as a 2004 K1200RS/GT.

I am right there with you, my bad as well!

I guess the R system is based on the GS system, and I should have realized that when the OP posted a photo of the ABS unit clearly showing the reservoirs there. Anyway, the good news is they’ve been checked and fluid level removed as a source of the issue.

Best,
DeVern
 
Working on these systems I've found bleeding the system properly to solve most problems. Other problems have been the sensors at the lever and pedal not aligned properly. I have gotten the high pressure code before too. I bleed the secondary system a bit and all was well. Figured I had overfilled the reservoir.
 
Bleed the whole system and still received the same error code.

Using the procedures outlined here:
http://users.rcn.com/dehager/service/service_abs3.pdf

and here: (GS, but the elements are similar):
https://www.advrider.com/f/threads/flushing-bleeding-brakes-r1150gs-another-pictorial.455142/

If you’ve bled accordingly and have verified that the piston you referenced is not stuck, I’m not sure what your next step is. A correct flush and bleed on these systems along with verifying fluid levels and microswitch adjustments and operation usually clears things up…

Best,
DeVern
 
Check the level sensors at the Servo unit. I think you can use a jumper wire. Also there is a switch under the rear brake foot lever that sometime becomes mis-aligned.

How bad was the color of the fluid you pushed out?
 
Was just rebleeding the brakes and got a puff off smoke from the abs pump. Now no servo brakes on front or rear. Assuming this means the pump just died. Any suggestions of other possibilities?
 
Have it rebuilt (prob'ly won't be happening for a while), bypass it so you're back to "manual" hydraulics, or maybe refill the smoke...
Smoke.jpg
Note that this is NOT the BMW-Approved stuff.
 
All electric/electronic devices work on smoke.
If you release it the device no longer works.

What likely happened is one of the motors had a locked armature.
This blows the power Mosfet transistor on the main circuit board.
The brushes wear down on the motors as well and cock in the guide.

The unit will need to be rebuilt.
AFAIK Module Masters is not taking any at the present time.

I have fixed 3 but the problem is sourcing the replacement components. Unobtanium unless a donor unit with good components are available.
 
Was just rebleeding the brakes and got a puff off smoke from the abs pump. Now no servo brakes on front or rear. Assuming this means the pump just died. Any suggestions of other possibilities?

First, check fuses and external wiring to make sure they are not the source of the smoke.

If the pump has indeed failed you pretty much have three options. 1) A new pump from BMW, very very pricey and availability might be a question. 2) Bypass the ABS system and just run with conventional brakes. 3) Contact ModuleMasters in Idaho and inquire about having your unit rebuilt. That option may be iffy, tho, as for years they’ve been promising repair capability on that series of pumps but I’ve not personally run across anyone, or heard from anyone, who’s been able to get one rebuilt—due to lack of parts availability, according to MM.

Best,
DeVern
 
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