Intermittent ABS Fault

Watty100

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2007 bike........ when out and about more often than not the ABS red light comes on and stays on. Switch off ignition and back on again, it re-sets and all is well until it comes on again. Riding at speed, high revs, bumpy roads all seem to provoke the fault, a gentle ride through town to/from work and its fine.

GS911 (Thanks Roger of this parish) tells me that its an "ABS pump fault, interrupted power supply to ABS pump, fault no longer present".

All of which points to a loose/corroded/cracked wire or connector.

SO tonight I've got to the ABS unit, which has 2 red positive wires, one brown earth wire and several other wires. The 2 positives and the earth wire all show up as good with a test probe inserted :rolleyes: and no amount of pushing/pulling of the loom can provoke as much as a flicker in the probes LED.

Has anyone encountered this fault and if so whats the fix?
 
Sounds similar to mine and many others. the fault is normally the brushes in the ABS pump motor sticking in their holders. You can either spend a fortune on a new ABS unit from BMW or take the old motor off the ABS unit and clean and open up the brush holders. I did this and it worked for a while. the long term fix for me was to replace the brush assembly on the motor with one from a ford fiesta. Have a search around there are many posts on this and other sites showing how its done.
 
Motoscot - well respected independent motycycle engineer specialises in these and similar ABS fixes and guarantees the fix. About £330 iirc. He's on here too I think. Near Luton/ Bedford. Several threads about it but phone/email/PM him and he'll give u options. He does loads of them.


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Now Fixed

Thanks for the advice, and for anyone browsing the thread looking how to fix their bike, heres my take on the subject: :rob

First and foremost, if you get the brake failure light coming on, get the fault codes read by a dealer/friendly GS911 owner. This fault cropped up shortly after replacing the brake discs when conventional wisdom would have pointed me in the direction of the wheel sensors.

You will need to remove your ABS unit, remove the faulty pump from it, repair or replace it, re-fit and ride!
I chose to fit a used pump from a Fiesta.

The Ford Fiesta part number you need is CV21-2C405-AE. There are vids on YouTube of how to do this so I'm not going into detail of what to do (This one is a simple photo montage https://www.youtube.com/watch?v=zFNkluQ_cbM

What I will add is that before you start, drain the brake fluid, it will save a lot of mess. Just open the bleed nipples on all 3 calipers, remove the reservoir filler caps and pump out the fluid until the reservoirs are empty then leave it to drain a bit longer.

When I put it back together, the front brakes bled quite easily and I soon had pressure at the lever. The rear was a bit more involved, I had to loosen the "fluid out" banjo bolt on the ABS module and bleed from there to get all the air out so fluid would then flow to the caliper.

Test rode the bike yesterday morning and all was well. Fixed for a £40 used pump and a bottle of brake fluid.:thumb
 
My concern with using the whole pump motor from the fiesta is that the eccentricity on the shaft is greater in the fiesta than it is in the BMW. I have no idea what (if any) issues this might cause. Thats why I decided to take just the brush holder assembly from the fiesta and re-use the BMW spindle and windings. Its a little more work and you will need to buy a new bearing (about £2.50).

Either way, its way cheaper than getting a new ABS assembly from BMW!
 
Oh, I should add... that if you are patient and have small enough hands you can remove the motor from the ABS unit without removing the abs unit from the bike and so don't need to drain any fluid.
 
How did you resecure the repaired motor to the ABS pump housing ?.
 
there was enough spare metal to peen over a little but i didn't feel that was secure, and was fiddly with the limited access so I also used West Epoxy and put a small bead all round the joint. Has been fine for many miles now.
 
there was enough spare metal to peen over a little but i didn't feel that was secure, and was fiddly with the limited access so I also used West Epoxy and put a small bead all round the joint. Has been fine for many miles now.

+1 what I did as well.
 


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