ABS Fault 850 GS

[Seamaster]

Hello everyone in GS land.
I have developed a fault on my 850 GS with the ABS, in that the ABS lights flash alternately and the ABS does not function. The bike has done 12K miles and the battery is kept topped up with charge using a battery optimiser and appears to be in good condition .
In the last 18 months the bike has probably only done about 500 miles.

No doubt this subject has been covered before but a search of the site did not help.

Is there anything I am missing.
Regards
Rideaday ( if only!)

 

[Tarka]

If those symptoms occur immediately after starting off...try stopping and switching off the ignition,then restarting.

Also,check the airgaps between the ABS sensors and the ABS rings are within tolerance.

Check there`s no crap between the teeth of the rings.

Check the cable from the ABS sensors for damage.

Can`t really think of anything else,unless the lack of use has led to a solenoid valve ( or suchlike gubbins in the ABS unit ) sticking........

 

[wessie]

Hello everyone in GS land.
I have developed a fault on my 850 GS with the ABS, in that the ABS lights flash alternately and the ABS does not function. The bike has done 12K miles and the battery is kept topped up with charge using a battery optimiser and appears to be in good condition .
In the last 18 months the bike has probably only done about 500 miles.

No doubt this subject has been covered before but a search of the site did not help.

My bike started this palaver after 4 years. Even though you charge the battery up with an Optimate it is probably not efficient enough to supply the demand from the starter motor and ABS system.

IIRC correctly, the ABS controller monitors the battery voltage and reports a fault if this voltage drops below 11.2V. With a tired battery this voltage drop is not uncommon and BMW should've designed a circuit to cope with a lower threshold.

You can diagnose this fault in 2 ways. The first way is to use a multimeter (analogue is best but a digital with a max/min memory will do) to monitor the battery volts when you press the starter button. If the voltage drops below 11.2V then you need a new battery.

The second way is to connect another battery in parallel with the bike battery i.e. jump start the bike from your car or whatever. If the bike starts & the ABS initialises then you can deduce that your battery is knackered.

A replacement battery from BMW is £72 ish. Alternatively you can get a more sophisticated AGM battery from a variety of suppliers. Search this forum for Hawker battery.

 

[Seamaster]

Thank you for the information I`ll have a play at it at the weekend.

 

[Steptoe]

Re-set it by earthing the centre terminal in the abs diagnostic plug under the seat - it's got a blue protective cover.

Run a wire from the centre plug to the battery earth ( the better the earth, the easier the reset ), turn on the ignition, hold down the abs button on your dash for approx 20 seconds, keep the button held down while youturn off the ignition - that should clear it. If your earth isn't very good, you may need to do it a couple of times -
Also make sure the abs button on the dash works, they corrode behind the connections breakoff, or the switch seizes inside, If it doesn't work, you can't reset the abs .

 

[hops]

Have a look

at this thread , especially the link from pragmatix. Your ABS may need to be reset if the battery is not the culprit.

 

[Seamaster]

850 GS ABS

I have reset the ABS as per all your instructions, just need to road test.
Thank you very much you are all very nice people .

After 5 attempts of the earthing trick I decided the rear sensor was dirty so removed it and cleaned it up with a bastard file, banged it back in with a lump hammer then tried the earthing trick again and everything seams to work.

 

[Seamaster]

850 ABS not working

So much for my flipancy, drove 20 feet down the road and the two ABS lights started to flash alternatly and no amount of resetting will stop them.
The rear ABS ring is not shiny like the front but the teeth appear to be crisp and clear of particals of dirt.

 

[Alex]

I had the same problem a couple of years ago. The main ABS relay was about to die so it was not providing consistent voltage. This would confuse the electronics and throw out error codes which made no sense. The relay I could only find in my local BMW dealer, but upon replacement everything went back to normal. Maybe that's the case with your bike as well?