1150GS iABS Fault

[Boxergsa]

Hi

I didn't intend my first post to be so technical, but sometimes you can't choose: I have an '02 1150 GS Adventure with 50k miles., and integrated ABS. I have had it from new.

I have an iABS fault - intermittently - while braking lightly/moderately with front brake lever, the abs lights come on and I lose servo assistance (bit of a wake up), I release the brake, and the brakes reset themselves and operate ok again. Rear brake only, or firm/emergency stops do not provoke the fault.

My dealer put it on the diagnostic and came up with 5 fault codes:
4119, 4219, 4319, 4419; - all pump errors and intermittent
45245 - brake light defective, but the bulb is ok - both filaments.

He advised he can investigate further but it is probably the servo - £1400 for a new one - but did advise a check of fluid level in the servo. Checked and both circuits at max.

Last system fluid replacement was 2.5 years ago - so 6 months overdue.

I have a new battery.

I have now completed a fluid flush/bleed of the complete system. The problem I found when bleeding the circuits was on the rear brake control circuit 'rear metering bleed screw' I kept getting air bubbles - just from this bleed screw, not from the 'rear integral circuit' or the 'rear control circuit', so they are not from the rear reservoir - could this be a leak in the modulator and the cause of my fault?

Road tested over 40 miles and fault persists, although it does not occur as often.

Am I right to assume a servo/modulator problem, and the options are either replace it with a breaker item, or convert to normal brakes? Or should I be doing something else?


Thanks for any advice/guidance.

(I have found threads covering the conversion to normal brakes).

 

[eonisbkuk]

i had a failure of mine while going into the blackwall tunnel and filtering still had normal brakes no abs managed to find 2nd hand unit from either motorworks or motobins for about £200 and had that fitted

 

[DollyRocket]

Hi Boxer, welcome to the forum.

I have 'exactly' the same fault - or did have about 2 months ago. I spoke to the wise people of this forum and they all said change the rear bulb, which i did - and not had a problem since. Not sure whether I believe it is a genuine fix ( Being an engineer I don't believe faults like a bulb are linked to a servo).

However, I think the general fault is that the pressure in the servo is not building fast enough? This could be due to the motor - possibly carbon build up on the stator (assuming it is a brushed motor). I am waiting for mine to fail again and then I will plan on stripping it out and stripping it down to see where the fault could have come from - I have access to pressure test gear and electronics expertise so I might be able to build a test rig.

I would like to know if I rip out the servo will the braking performance be the same as the pre-servo bikes (or has the addition of the servo caused a change in the caliper which could effectively reduce braking power when hand pumped?).

 

[Boxergsa]

Hi Guys

Thanks for your replies.

I have checked out secondhand modulators and they are becoming rare, with none available at the moment - and I am led to believe that as few as 20% install fault free.

Also - due to the vintage of bikes fitted with the iABS, failures are becoming quite frequent - evidence; Motor Works have a list of parts you require to convert to normal brakes, including a wiring diagram to assist.

It is also suggested that the failure is often the diaphragm inside the modulator, between the control and braking fluid circuits, and that this can be damaged even by energetic pushing back of caliper pistons during a pad change. This could be true as I replaced the rear pads quite recently.

I have tried the replacement of the rear brake bulb - but no resolution.

I am now resigned to converting to normal brakes and am just waiting for the parts - under pressure now as I have a trip to Scotland planned, departing Friday!

All the posts I have read say the conversion to normal brakes is quite straightforward and that the resulting braking performance is good - with more feel than the iABS system. At least one post referenced brake efficiency check (a la MOT) with similar results to the iABS system.

This check is advisable so that when you inform your insurance company of the mod you can evidence with the official printout that the brakes are functioning 100%.

I'll let you know how my conversion goes.

 

[MattW]

Good luck

I'll be interested to read about your experience doing the conversion - heard about it many times but never read anything about actually doing it.

 

[Steptoe]

- heard about it many times but never read anything about actually doing it.

It's all in here - including the wiring instructions that i spent half a day sorting out.

The parts cost about £70, so don't go buying any ridiculas priced conversion kits.

 

[Fanum]

( Being an engineer I don't believe faults like a bulb are linked to a servo).

a little knowledge can be a dangerous thing

try taking out a bulb on an i ABS equipped 1150gsa and see what happens

PS it's because checking the bulb is part of the 'start up ' routine for the abs system...no bulb, check-list incomplete, no abs.

EDIT......even if both filaments are demonstrably ok (continuity meter) it's still worth changing the bulb as a first course of action- I've had damaged bulbs where I can only assume the filament wouldn't pass enough current to set the abs yet the bulb was fine across both terminals to earth- swapping the bulb solved the problem immediately.

 

[Boxergsa]

Hello again

Well, what a week its turning into. Motor Works did not have the 3 way hydraulic distribution unit to plumb the front brakes and local BM dealer closed on a monday. SBW said they would order it in and post it to me to arrive Wednesday. Called Tue and they had the part (hooray) but did not have time to post it! So I set out with intermittent brakes - St Ives Cambs to Hertford, nice ride, rush hour in Hertford, collected part and went on to a club meet at a pub in Somersby nth of Oakham. All went really well, I did not use the front/linked brakes at all - really worked on my forward planning. Arrive Somersby, stop bike, try to restart to move it - engine turns - does not start. After loads of exploration, give up - it's clear it's the fuel pump, and I assume electrics - wrong! End up calling RAC, resigned to recovery - RAC man does excellent diagnosis (thanks Wassim from Derby) and diagnoses sticking fuel pump - strip it out of tank, hit it with a spanner, and its off again - 11.30 at night. good job I did not assume recovery and have a few pints!

So today I ordered a new fuel pump from Moto Bins (cheapest source without using a car alternative since I need to be in Scotland on Friday), and set about ABS conversion.

Thanks to everyone on their posts on how to do this. I took my time since I am not the worlds most natural mechanic. Rear brake replumb easy, front brake would be easy if bolt had not seized then sheered in frame near headstock, but sorted in the end. Remarkably little air out of front calipers when bleeding but all seems ok.

Routing new switches takes time, I sorted the wiring as per Steptoe (easy, many thanks), even soldering to make decent connections, then (not sure if its the right thing to do) used the connectors from the old switches on the new switches to connect them to the loom, and it all works first time with no blown fuses. Had to remove bulb from instruments saying brake failure (go on, tell me there's an easy work around for this) and hey presto, time for test ride.

Brakes feel great - good feel and just as powerful as iABS system. Thumbs up on all counts. Back home checked everything and found slight fluid weep - tightened ever so slightly more (don't want to strip anything), and will test again tomorrow.

I intend to weigh the ABS bits I removed (I know it's supposed to be about 5 kilo's), and will think about abs sensors, sensor rings etc once back from Scotland. Nice space under tank now - would be nice to move battery so that it could be used to stash waterproofs or whatever, but it doesn't look straightforward - it's going to frustrate me knowing the space is there and not being able to use it - oh well, just have to be happy with the weight saving.

I spent about 7 hours (very steady pace) and £90 - £43 for the new switches, £29 for the distribution unit for th front brakes, £5 on brake fluid, £? (can't remember and its late) on bleed nipple, then postage. haven't counted petrol to Hetford or the cost of a new fuel filter - hey ho, still lots cheaper than paying someone else to do it, or replacing the modulator!

Thanks again for all the advice guys - here's hoping the fuel pump does arrive tomorrow, and then I'll be off to bonny Scotland - forecast for Friday is rain, but then it is Scotland!

 

[sockpuppet]

Had to remove bulb from instruments saying brake failure (go on, tell me there's an easy work around for this) and hey presto, time for test ride.

AFAIK you can just remove the ABS relay in the fuse box.

 

[Boxergsa]

- remove the relay - that rings a bell, must have read it somewhere before - I'll leave it in now, may need it as a spare.

Fuel pump arrived and fitted - running sweetly again - and just finishing packing for the Scotland trip, life is looking up.