Problem with rear brake / ABS

[Greybeard]

Was wondering if anyone has had a similar problem to the one I have just discovered, as a quick search I did on the forum didn't show up anything obvious.

About 4 weeks ago I took my bike out for a short ride with some mates and I noticed the red triangle warning light was on and the ABS brake failure warning sign was also rapidly flashing.

It seemed that the front brake was still OK but I had no rear brake. I normally just use the front brake lever for braking.

When I stopped, turned the ignition off and on again, the problem went away - all was normal.

BUT, over the last few weeks I've noticed that the same problem crops up at seemingly random intervals. Today it happened just as I was stopping at a cross roads and the ABS didn't apply the brakes as expected - ended up just over the line and rather close to a passing bus. Close one. Turning the ignition off and on again got things back to normal again.

It's a 2005 1200GS, nearly 12000 miles. Somewhat overdue for its annual service (due in June) as I'm planning to get the service and 12,000 mile inspection done at the same time (next month).

Anyone else had similar experiences - if so, what should I do?

By the way, I do like ABS and I'm not thinking of permanently disabling it etc. etc...

Thanks

 

[MOTOTECH]

Take it to your local dealer or independant who can read the fault memory, but I have a sneaking suspicion the ABS pump is giving up.
Brian.

 

[blackbird]

If it is the pump I hope you have extended warranty as you are looking at the best part of £1,200 the joys of non ABS

 

[luckylucian]

Have you checked the rear ABS sensor, if it has metal flakes on it, the Final Drive is on the way out. This sometimes comes with speedo problems as it uses the rear ABS sensor to measure speed

 

[nedflanders]

had the warning triangle appear on mine a few times, also the speedo stopped working at the same time. dealer found no fault codes but shortly after the battery died, replaced it and alls been well since.

 

[Michaelk]

Rear Brakes

I had an old '93 R1100RS with ABS.It was one of the first rs's with ABS and as a previous tosser has said, when my problems atarted it was due to the battery not having enough power to supply the ABS unit.

Bought a new battery, lots of starting power, no problems since.

 

[Greybeard]

Not got extended warranty so I really, really, hope it is not the pump. It would be devastating.

Thinking about it, the speedo did die the first time it happened, and a guy at work also had similar problems which went away when he charged the battery. I had a new battery while the bike was under warranty, so I'll try putting it on charge, but I've been doing quite a few miles recently so I would be surprised if it isn't fully charged already.

I'll also check for bits on the rear sensor - I did have some new tyres fitted recently by a non-BMW dealer, I wonder if something wasn't put back properly?

Thanks for the advice chaps. I'll post an update once I've done some checking.

 

[patzx12]

is there anyone near you with a GS-911? it may show up the fault.

 

[Greybeard]

Not sure about anyone with a GS-911 - looks interesting though. As its shortly going in for a service (I'm taking to the Boxer-Passion Motorrad dealer in Rennes, Britanny) I may just ask them if it keeps happening.

 

[mpdouglas]

On the R1100S that I had, there was a golden rule that you turned the key on and waited 5 seconds or so before trying to start the bike. This gave the electrics enough time to "wake up". If you started the bike immediately after turning the key, you would frequently get ABS warning lights on the dash.

 

[norfolkbikerlad]

I had a wierd one the other day, took the bike in for a service, once home the next time out I noticed the speedo didn't work and the abs light on with brake failure flashing rapidly, turned ignition off, then on and it went, next time I started no speedo etc, called into the dealer, Balderstons, explained to them and a nice chap came outside and moved my right hand guard round slightly, as it was just catching the front brake lever!!!!! Been perfect ever since, good old Balderstons.

 

[Dahoum]

Sounds similar to the problems i was having just before i had to have the wiring loom (yes all of it) replaced due to a bracket eroding through a wire cluster and shorting the abs system out.

it was well out of warranty but they replaced it labour costs only

might be worth getting this checked - it took them three visits before they found this was the fault.

 

[Greybeard]

Well it doesn't seem to be the battery. I charged it overnight and then had a brake failure warning come on during my commute to work this morning... not a good sign.

 

[GSband]

Hi, I had the same thing happening to my R12GS bought in june 2005. In heavy stop-and-go traffic in october 2007, same symptoms as you describe (rear brake doesn't function, ABS light flashing fast, problem disappears temporarily after contact off - on - check). First time in my life on any means of transportation that the brakes failed. I was pissed.

Brought bike to dealer, bike was diagnosed with failure '6234' which means problems with the brake pressure module. Only one solution : replacement.
Although bike was out of warranty, dealer replaced module with new one, me not having to pay the let's say 1000£... And, funny, the mechanic told me this might happen again, and that there must be a reason why BMW stopped using assisted brakes on the new ones.

Now what may interest you : this is not uncommon on the BMW bikes with assisted brakes, I know of similar stories. And BMW does not like the publicity about the brakes not functioning. Trustworthiness of BMW, resale value of the bikes etc etc. I guess that's why a bunch of customers get their brake module replaced for free. Of course, your dealer has to be 'sympathetic' to your problem, and it helps being a 'good' customer. A great way to bind customers to the BMW service, I'd say...

I sold the bike immediately after the free repair; no way I'm driving a machine whose brakes fail... I'm now driving a december 2007 model; it doesn't have these assisted brakes.

 

[Greybeard]

Quandry. Take bike to local (no longer bike) dealer that still has a qualified bike technician, and who I got the bike from - or, wait until I get the bike serviced as planned at the Rennes Motorrad dealer? The local BMW dealer just sells cars now, so not sure if they have much interested in keeping bike riders sweet, though to be fair they have done stuff they didn't have to before for me on previous bikes.

Pros of getting it looked at locally -
1) they may feel some obligation to get it fixed even if out of warranty (maybe?) based on previous behaviour
2) I will feel safer if I get it fixed sooner rather than later...
3) It may just be something knocked out of alignment when the tyre got changed (I need to check the dates to see if the problem only manifested itself afterwards).

Cons -
1) they may whine on that I didn't get it serviced on time.


Pros of waiting and getting it sorted at the Rennes Motorrad dealer
1) they have probably seen it before (maybe?)
2) more chance they have the part(s)?
3) it may be cheaper to get fixed in France

Cons -
1) they didn't sell me the bike so have no skin in the game
2) I may die.


I think I may have made the wrong decision about not taking extended warranty times two years - oh well, never mind. Think I'll make the local phone call tomorrow to see what they say.

 

[JFC]

exact same thing happend to me, down to pads and disc worn so barke pistons out so far, hydraulic oil in abs thingy low it thinks problem and shuts down back brake.

other stuff happened - speedo to zero, and servo on all the time

ignition on/off and problem would go away for a bit

replaced disc and pads and all ok

 

[Greybeard]

Thanks for al the feedback. The bike is booked in on Wednesday at the local dealer to see what they say...

 

[Pukmeister]

Exact same thing happend to me, down to pads and disc worn so brake pistons out too far, hydraulic oil level in abs modulator low, it thinks a problem and shuts down back brake.

other stuff happened - speedo to zero, and servo on all the time

ignition on/off and problem would go away for a bit

replaced disc and pads and all ok

Thanks for the update JFC, suddenly it all makes sense. A low hydraulic fluid level in the pump/modulator internal reservoir (not the handlebar one) would cause pump cavitation and a loss of hydraulic pressure. I can't believe so many R1200 model ABS modulators are actually 'failing', it's probably just a lack of dealer experience.

I tried bleeding a mates 1150GSA wheel cylinder (with servo ABS) a few years ago and we wondered why the handlebar reservoir stayed full, eventually we ended up at the dealers getting it flushed and bled from the pump unit when the ABS pump did as you describe.

I think I may change that worn rear disk after hearing your story.......

 

[RogerJ]

Problem With Rear BrakeABS

Ditto on the harness replacement cure for intermitten failure, and, even for full red solid non flickering ABS warning light. Once you have eliminated a bad battery cell and proper cranking voltages being maintained, then check via GS911 or GT1. Follow the routes under ABS in both. If there is undersupply of voltage to the ABS pump the GS911 will give you two fault codes. The GT1 will show you on a bar graph the voltages and give you the same number codes. If power is not arriving well at the ABS pump connector you should investigate a loom problem having ruled out voltages and continuity coming from the ignition switch to the pump and from the battery to the pump. The wiring looms are delicate beasts. I am informed there is even fibre optic inside. Mine is on its way in for loom and pump replacement. Once the loom is not good there is nothing to do that I know to bring it back.

 

[Greybeard]

... hydraulic oil in abs thingy low it thinks problem and shuts down back brake.

I'll mention this to the dealer tomorrow although I had the rear brake pads replaced last year so I think all is OK in that respect.

As far as the GS911 comments, I don't know anyone that has one of these gizmos so I'll have to rely on the dealer to check out the electrics.