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Discussion Starter #1 (Edited)
It's my own fault really. I've hardly used the bike at all this year (we had a baby, I changed jobs, twice, and we moved house). It stood for long enough to kill the battery. I finally replaced that, and now I'm getting the dreaded failure indications.

I've already topped up both reservoirs and charged the battery overnight, but the indications return by the time I get to the end of my road.

Reading the posts here seem to suggest the steady ! indicate an ABS failure, but what's the consensus? Is there anything else worth changing/checking first? And if not, what bit actually gets replaced? Is it the whole aluminium unit I've just filled up with oil?

Many thanks in advance

Nick

PS For what it's worth, the pump runs when either the brake lever or pedal is pulled/pressed, and the brakes still stop the bike as well as they ever did.
 

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Hi Nick

I had the same problem with my LT after leaving it for a lengthy time. Yes the brakes still work, but, eventually my pump gave up and it was not a pleasant experience. It gave up when I pulled the brake coming to a busy T junction. The dealers here are looking for about 2 grand to sort it. If you plump for getting it removed there is different ways to do it depending on the year of your bike so you have to get the right way to do it.
 

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Discussion Starter #3
Hi Kevin

Thanks for the reply.

I forgot to say, my bike is a European 2004 (ie post-facelift, with iABS).
I don't think I want to try and remove it, and I certainly don't want to ride with it indicating something has failed.

I'm just wondering whether it's worth trying to repair it.

Nick
 

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Hi Nick

Yes i'm Scotland. Mine is a European 2005 model. I removed mine and the brakes are just fine you just don't have ABS any more, which on mine doesn't matter as it's been triked so stability in the wet isn't a problem.

In the UK there doesn't seam to be a lot of places that are willing to repair the units as it is a lot of work. even if BMW repair it they will only give you a years guarantee on what they replace anyway.

Kev
 

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A while back someone posted there is a place in Germany that can repair iABS modules - not sure if just first gen or second gen like yours. Hopefully someone will post up the source. Good luck!
 

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Nick,

"Sometimes" that can be just a bad battery. Make sure you fully charge it with a charger and not a trickle charger. You might also want to do a load test on the battery.
HTH
 
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Discussion Starter #7
Hi John

I did wonder about that, as it did happen straight after I fitted the battery. However, I charged the battery overnight using my motorbike battery charger/maintainer (Oxford Oximiser) and it was in 'maintain' mode this afternoon when I disconnected it and tried a 2nd time, which I take to mean the battery is fully charged.

What configuration would you recommend using to do the load check, and what voltage is too low? The engine turns over with no struggling, so I reckon the battery is fine, but I'm certainly willing to run a test before heading down the road of a replacement ABS unit.

Many thanks

Nick
 

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Below 10 volts while engine is cranking is too low. Having access to Germany from the UK you should be able to find a used but good module or have yours rebuilt. Sometimes it is hard to read the voltage fast enough on a digital meter. I have an older analog around for odd situations.
Your thinking, the bike is older and do I want to put big money into it, is a good one. Always difficult, what is the cut off point.
 

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What configuration would you recommend using to do the load check, and what voltage is too low?
Usually the vendor where you purchased it from will have a tester to do a load test. Short of that with the bike not running and key in off position you should see over 13 volts. With the bike running the alternator should boost it to about 14.4 volts. If the battery is weak during starting it will drop below 10 volts and that could cause a fault.

The engine turns over with no struggling, so I reckon the battery is fine, but I'm certainly willing to run a test before heading down the road of a replacement ABS unit.

Many thanks

Nick
It is possible to start an engine with 10 to 11 volts although this bike has a lockout to prevent starting at to low a voltage.
 

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Discussion Starter #10
Hi John

Sadly, I mail-ordered the battery, so I can't get it tested by them.
I get 12.69V with everything off, 14.17V at idle, and during start, it looked like it dropped to about 10 1/4 V on the analogue gauge.

Does that sound ok?

Would a GS911 tell me exactly what is causing the fault light?
Are there any other quick checks I can make on sensors etc?

It seems I can get a 2nd hand ABS unit, untested but with 6 months warranty, for £380 here. I'd be happy to pay that, but would like to be able to isolate other components/causes first.

Ta!

Nick
 

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Hi John

Sadly, I mail-ordered the battery, so I can't get it tested by them.
I get 12.69V with everything off, 14.17V at idle, and during start, it looked like it dropped to about 10 1/4 V on the analogue gauge.

Does that sound ok?

Would a GS911 tell me exactly what is causing the fault light?
Are there any other quick checks I can make on sensors etc?

It seems I can get a 2nd hand ABS unit, untested but with 6 months warranty, for £380 here. I'd be happy to pay that, but would like to be able to isolate other components/causes first.

Ta!

Nick
Nick,
Do you see these warnings described in 1st post (steady ! with flashing ABS-Brake failure) ONLY AFTER you start moving -OR- does it shows right after ignition is turned ON (after the ABS internal self-check that may last 6 seconds).

If you see these only when after the bike is moving (how long?) then you may have a dirty wheel-sensor -OR- incorrect gap at either wheel sensors.

A GS911 readout of ABS faults would certainly give us good info about above case (wheel sensors). Otherwise, if the internal pressure sensors (inside ABS unit) are showing an error, then the ABS-unit may be on its way out.
 

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Discussion Starter #12
Hi John

Nick,
Do you see these warnings described in 1st post (steady ! with flashing ABS-Brake failure) ONLY AFTER you start moving -OR- does it shows right after ignition is turned ON (after the ABS internal self-check that may last 6 seconds).

If you see these only when after the bike is moving (how long?) then you may have a dirty wheel-sensor -OR- incorrect gap at either wheel sensors.

A GS911 readout of ABS faults would certainly give us good info about above case (wheel sensors). Otherwise, if the internal pressure sensors (inside ABS unit) are showing an error, then the ABS-unit may be on its way out.
Brilliant - that's exactly the sort of info I was hoping for.
When I start the bike, I get the normal indications (slow flash of Brake Failure, no '!'), and they stop as I ride off. Then, on one occasion 15 minutes into a ride, once on my first brake application, and once about 2 minutes into the ride, I notice the warnings, as described in the title, appear.

I'll check and clean the wheel sensors. However, the fact that the initial test passes, and the slow flashing stops, means the sensors are working at least partially, I guess?

Thanks again for the post.

Nick
 

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Hi John



Brilliant - that's exactly the sort of info I was hoping for.
When I start the bike, I get the normal indications (slow flash of Brake Failure, no '!'), and they stop as I ride off. Then, on one occasion 15 minutes into a ride, once on my first brake application, and once about 2 minutes into the ride, I notice the warnings, as described in the title, appear.

I'll check and clean the wheel sensors. However, the fact that the initial test passes, and the slow flashing stops, means the sensors are working at least partially, I guess?

Thanks again for the post.

Nick
First of all, to clarify for others reading this, everything posted earlier (and now) assumes you have the IABS with servos (models 2001-2009 with the noisy servos motors when you apply brakes).

During initial internal check phase (after ignition ON) the IABS system can detect if a wire of either wheel speed sensor is broken, HOWEVER it can only detect a weak signal (dirt on sensor -OR- incorrect gap) after riding for a distance. In some cases this fault may appear only at higher speed.

A GS911 readout of faults would confirm if fault is from either wheel speed sensors. As I have posted earlier, the 2 warnings you are seeing could also be caused by an internal fault of the ABS unit, so a GS911 error readout would clarify this ambiguity. IF YOU ARE SEEING THE FAST FLASH pattern (4 times per second) then there is a HIGH probability this an internal ABS unit pressure fault - this is not an easy fix compare to the sensor gap issue. In the USA, no one yet can overhaul these IABS units, but there is one in Germany according to 2 riders from Europe who posted here recently.

Meanwhile, if you are patient and handy, you can measure the air gap for both sensors with bike on center stand. Use a set of feeler gauge to measure distance between sensor and dented wheel - make sure to measure at least 6 places all around as the dented wheel is never perfectly flat. Do not force the feeler gauge in between - it should slide with minimal friction.

As documented in BMW shop manual and CLYMER, acceptable values for air gap are: 0.2 to 1.5mm (0.008 to 0.06 inch)
My experience is that it is much better to be in the middle of this range to avoid a weak signal caused by some dirt on sensors or dented wheel, so I always try to aim for: 0.4 to 1mm (0.015 to 0.04 inch). Now would be a good time to clean any dirt on sensors and dented wheel(s).
 

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Discussion Starter #15
Hi all

Thanks for the replies so far.

I shelled out for a GS-911, and it reports fault code 17438 Pressure in rear wheel circuit too high.

Anyone got any ideas about this? It sounds even more like a fault within the ABS unit now, but I might try flushing some new fluid in first (I'm ashamed to say I've never changed the fluid, and I've owned the bike a few years now. :frown: )

Nick
 

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Hi all

Thanks for the replies so far.

I shelled out for a GS-911, and it reports fault code 17438 Pressure in rear wheel circuit too high.

Anyone got any ideas about this? It sounds even more like a fault within the ABS unit now, but I might try flushing some new fluid in first (I'm ashamed to say I've never changed the fluid, and I've owned the bike a few years now. :frown: )

Nick
Hi Nick

I had exactly the same codes when I checked mine. I tried changing the fluid on mine and it did nothing. I cleaned out the two filters that are in the unit with no success either. When I eventually took my unit out and apart I found that water had got into my unit somehow and there was rust inside it. I tried cleaning the rust out and re-assembling the unit but it still came up with to much pressure. Hopefully this has not happened to your unit.
 

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Hi all

Thanks for the replies so far.

I shelled out for a GS-911, and it reports fault code 17438 Pressure in rear wheel circuit too high.

Anyone got any ideas about this? It sounds even more like a fault within the ABS unit now, but I might try flushing some new fluid in first (I'm ashamed to say I've never changed the fluid, and I've owned the bike a few years now. :frown: )

Nick
As I had suggested in an earlier post, the flashing sequence you had could very well be an internal pressure error. So at this point I would try the followings before we assume the ABS unit needs repair (not an easy task to find a shop to repair these IABS unit with servos).

Two jobs to try, from easy to more complex / difficult:

1) Reduce the REAR brake pedal adjustment in case you have constant pressure from the rod between the master-cylinder and the pedal. The procedure and adjustment gap are described in BMW repair manual and CLYMER manual.

Make sure ignition is OFF while you work on this. On next start / ride, always wait 8 seconds after ignition ON before you start the engine (ABS internal self check is completed)


2) Do a full bleed procedure of all circuits. If you have never done this on these IABS models, I would suggest you get some help the 1st time. If the ABS unit has not flushed / bleed every year (wheel circuits at the minimum) as suggested in maintenance schedule, you may have internal corrosion.

Anecdotal evidence from last 13 years on all BMW forums seems to suggest that IABS models that are not being ridden a lot AND not being bleed as per maintenance schedule, have more failures.
 

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That one (fault code 17438 Pressure in rear wheel circuit too high) is sort of fixable according to a guy in S.A. He posted that if you remove the dome looking thing on the ABS unit that is in the rear circuit ( the one in front of the shorter reservoir) and manipulate the little piston on the inside of it sometimes this will eliminate that fault. The Domed thing is a relief valve. Tough part is getting a wrench on it.
 

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That one (fault code 17438 Pressure in rear wheel circuit too high) is sort of fixable according to a guy in S.A. He posted that if you remove the dome looking thing on the ABS unit that is in the rear circuit ( the one in front of the shorter reservoir) and manipulate the little piston on the inside of it sometimes this will eliminate that fault. The Domed thing is a relief valve. Tough part is getting a wrench on it.
John,
Thank you for jumping in...

I was looking for an earlier post of yours where you had suggested the same fix with picture - went for supper and forgot to continue my search.
I also recall seeing this tip on the GS911 forums a while ago.
 

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John,
Thank you for jumping in...

I was looking for an earlier post of yours where you had suggested the same fix with picture - went for supper and forgot to continue my search.
I also recall seeing this tip on the GS911 forums a while ago.
Hi Nick

That is where the corrosion was on my system. It was both valves that were contaminated with rust. I couldn't get the pistons to free of enough to work properly, that's why I eventually removed the system altogether.

Kev
 
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