Doug,
My 1150RT ABS did exactly the same thing. Eveything seemed to be working except the rear system. Finally fixed by it by disconnecting and re-seating the connector to the rear brake pedal microswitch. I thought initially the switch was bad, but it turned out to just be the connector needed taking apart and re-seating. Nearly drove me nuts trying to find the problem. Has worked fine since.
Al - Ogden, Utah
Boxer bikes, dogs, and letterboxing.
2004 1150GS, 2009 1200RT
2006 Boxer dog (Paisley)
I did that already - in the process of checking out the microswitch, but I checked it again- internal inspection looks fine and the connector M/F bodies fit together very snugly with no play. Your experience suggests to me that I dig a little deeper into the wiring. That ABS relay on my bike is an incredible piece of work and makes it nearly or actually impossible to check the wires below the relay where they connect, but possibly there is a fault between the connector and the ABS relay that I can locate.Originally Posted by awagnon
Yes, this is about driving me nuts!
If I recall, the switch is a normally closed connection. I tried jumping the wires at the connector to simulate a closed switch and the ABS faullt went away. That's what made me think the switch was bad, but the switch tested OK with a meter. Put it back together and it worked. Or, if it's a normally open switch, unplugging the connector should resolve the fault if the switch is bad.
Al - Ogden, Utah
Boxer bikes, dogs, and letterboxing.
2004 1150GS, 2009 1200RT
2006 Boxer dog (Paisley)
Al, on mine the microswitch is NC and I will try that - jumping the pins at the connector. Yes, with an Ohm meter the switch tested fine at the connector. I had to use straight pins to get a reading but the brake pedal opened and closed the switch just fine.
I will try your method and see what develops. Thanks.
Update - rechecked the rear brake microswitch connector. Jumping the pins on the side that comes from the ABS relay did not change the flashing lights. Leaving the connector body open and turning on the ignition - the front brake lever would not fire up the servo. Interesting that the rear brake switch has to be in the circuit. Long ago the self-test quit working so I am puzzled that it goes part way through its thing.
Based on a thread I found at ADV rider, I took the bike out and stomped the **** out of the rear brake pedal a bunch of times. I could get the rear wheel to lock up by practically standing on the pedal. It did not do anything for the flashing lights however. The problem reported over at ADVrider sounded identical to mine and the guy took it to the dealer who could get the stuck valve in the ABS freed up with their computer but after that he exercised the rear brake circuit a whole bunch to keep the valve working.
I am totally cornfused and befuddled now. Anybody care to jump in with suggestions or ideas for further troubleshooting?
Dealer advice/diagnosis/repair is almost totally out of the question. He is in San Juan Puerto Rico and I live on a little island a day's travel away from there. They also have a shakey reputation and I could bring the bike back with more problems than it has now.
All and any ideas welcome!
It looks like your iABS modulator is finished. Been there, done that.
...waiting for a reply from beemershop on the analysis they may have for this.
Assuming you are correct, and the price tag for a new modulator beyond my modest retirement budget, what is your thought about an ABSectomy? I have read diverse opinions on it, and invite any thoughts on such a solution.
Thanks for the reply... frustrating as it is. 20K miles and a major component craps out!
Doug,
did you ever get this resolved? I'm curious. Just read about a similar issue on ADVrider:
http://www.advrider.com/forums/showthread.php?t=652797
J??rgen
Spokane, Golden
04 R1150GS adv
04 K1200RS last of the great bricks
Jurgen... and others. Sorry for the dead silence here - issue is still unresolved. I borrowed a GS911 tester and it tells me "Faultcode fouind 17438: Pressure in rear wheel circuit too high" and clearing the fault and restarting the bike gives the same result time after time.
Ted Porter at beemer shop did not want to tackle this via email or phone. I have another independent mechanic to contact, but otherwise it is SOL over here in little Vieques, Puerto Rico I fear.
Any words of wisdom out there? or otherwise encouragement or even discouragement?
ABS modulator about to be replaced with used one
ABS modulator replacement 2004 BMW R1150GS
To finalize this thread I have been through all the possible problems that have plagued this bike for 3 months now - 20,000 miles and the >rear brake circuit< has failed. A GS911 fault code readout says the pressure is too high in the rear wheel circuit. I found a used modulator for $600 with is about $1800 less than the best price for a new one. I gulped hard and asked them to ship it today.
Can anybody help me with installation tips? The lines look straightforwards enough (maybe I am too optimistic there) and of course all will need to be bled after changing the unit out. The great mystery portion of this looks to be the relay wiring. All the connections appear to be on the underside of the ABS modulator.
Any and all advice welcome. Meantime for anyone who owns a GS - if that ABS idiot light starts blinking rapidly along with the warning light, just hope that somebody puts you in their will cause the pain is going to be great!
Its a simple and straight forward job to replace the modulator. Having swapped mine about 4 times, I can now do it in 1/2 hour. When mine failed, I was unable to obtain a working used unit. I had 2 shipped to me, but both were defective, and both had different symtoms, but ultimately failed the post test and had flashing ABS failure lights. I ultimately had to purchase a new unit from BMW, which at the time cost $2400 US. Hopefully you will have better luck then I did! The hardest and most time consuming part of the replacement procedure is bleeding the unit, and since you have already done that on the existing unit, you will have no problems. It is a bit messy when you remove all the brake lines from the old unit, but there is not much you can do about that. Good luck!
Thanks, Bob - exactly what I was hoping to hear. The salvage yard sending me the replacement unit assures me 'it is a working unit' but I suspect that is their standard reply to customers. They offer a 30 day return guarantee and I got that from the main man.
I plan today to blow out the brake lines on the rear wheel circuit using compressed air in a last ditch attempt to clear any blockage and see if that corrects the problem. If not then it is ditch the ugly black box and put in the new one.
Doug,
If the "new" used unit is fully functional you may not want to pursue this, but if it is not you might consider contacting the poster on ADVRIDER.com named Steptoe. He seems to be a very knowledgeable independent BMW mechanic who resides in England and who has been able to fix some of these units. He hasn't divulged the process as he makes a living at fixing BMWs. You could get a quote from him on what he might charge to look at your unit and, if repairable, fix it.
Dave
2004 R 1150 GS
Thanks, Dave - excellent suggestion. The used units seem to be very scarce in the US at least. I had a response from a European/Russian parts source but nothing came of it. You gotta love the internet. I will post the results from the compressed air and then the swapout if it happens. Appreciate any and all remedies that might surface here.
Took a compressed air line and blew out all the rear brake lines - modulator to caliper and meter/control circuits to rear reservoir. Refilled everything and bled thoroughly - same problem remains. The servo does not fire up when the rear brake pedal is pressed. The modulator does not interact with the rear caliper at all (absent the servo I suppose it won't). Anyhow it was either fix it this way or spend $600 for a used modulator. Next step is to swap that out and see what develops from there. A lot of learning curve to one of these bikes
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