Hi - Have just bought myself another K75 ( Last one written off by white van man) but on investigating to find out why there were no ABS lamps lit, found the small blue ABS Relay in the bottom of the Relay box and the ABS Brain disconnected. Replaced those bits, then ign on, ABS and fault light flashing in unison. Got up past initialitation speed but no change. Connect up analogue meter to 3 pin connector and it reported Code 7 - Brain dead. Have sourced a working ABS Brain - what checks on the rest of the system should I make and instructions, before connecting the replacement ?

Not had anything to do with ABS before - any help much appeciated

Thanks in advance

Did you try to do a reset on the old brain and there should be no problem with just pluging the new one in. If you want the truth about it Tosi Tabuka is the guru of these ABSs.
http://bmwk10075abs1fix.web.fc2.com/

Hi George, welcome aboard.

Everything you need is on Tosi's site but its a bit compressed.

Several of us have just been through this so don't hesitate to request any clarifications.

Hi George I can highly recommend Tosi's website for the advice that it gives. The only point I would like to emphasis is when you clear the fault code down for best results use a analogue meter set to I (Amps/Current)

Tosi had to repair my ABS brain for me and today I fitted it back to the bike and dropped the relays back in and she works a treat. Just in time for the weather I think!

Hi all - thanks very much for your replies so far. Am about to start the checking proceedure from Tosi but am unclear about Ammeter use to reset the Brain, Twincarb - I have been using the resistance scale on an analogue meter to check the centre pin of the 3 pin plug. Iis this incorrect or is there some other onnection I have to find? Thanks in advance.

Hi George,

Yeah your right to use the middle pin on the 3 pin connector with the + lead and the - to a good ground point.

To read the fault code connect the meter in Volts DC. on an analogue meter you will see the fault code read out...

Switch the ignition on
You need to wait for a long pause of a high reading approx 10V.
Each time the meter then dips is a count.
When its dipped between 1 and 8 times that is the fault code.
At the end of the fault code it will show a long high reading approx 10V again it will then re-show the fault code.

To clear the fault code

With the ignition off.
Put the meter to Current shown as I or mA again connect the + lead to the middle pin and the - to a good earth.

Switch the ignition on while holding down the ABS reset button for 10 secs you will see the needle on the meter moving when the fault is reset you will see a dip.

You may need to do the reset several times before your clear of fault codes.

Out of interest what is the fault code your showing?

Hi a bit like me at the moment with ABS - Code 7 !!

First thing to check with a code 7 is to make sure the battery is fully charged, I didn't know the history of mine so replaced it as well to be on the safe side.

When you switch the ignition on can you hear the rear modulator buzz slightly approx 6-10 seconds from switching it on? and can you also hear the ABS relays clicking in for about a second?

I was left with a code 7 (sounds like a secret mission to me) i tried to clear it for ages in the end I got in contact with Tosi Tabuki and sent my brain off to him. He returned it in good time. my bike was still in bits so still didn't have a chance to test it until yesterday. All working perfectly now!

So I can personally recommend the service he provides. I suggest he will strongly suggest you fully charge your battery and try again.

I cannot recommend Tosi too highly he not only fixes the fault but as a precaution changes a few leaky transistors which when our units were built were the state of the art but the art has moved on from then and with age they are prone to faults so as a precaution he changes them, very quick turnaround too.

An amazing guy he bought a bike with a faulty ABS many years ago and opened up the ABS and immediately thought "I can fix this" because many years previously he used to design similar embedded circuitry. After a huge amount of time every weekend working out the full circuit diagram and all the coding in the system he set to work and fixed it. Since then he has become the go to guy for fixing these devices, what he charges is more than reasonable and he gives a warranty on his work. If you have a very strong constitution and a handy defibrillator and a trained ambulance officer go and look up the price from BMW for a new one

The ABS has saved my bacon and I would not be without it, every time I ride my bike I think of Tosi and his work helping keep me safe.
Regards,
K-BIKE

Without wishing to get into 'too many cooks' mode, just a quick two penneth...

These units, like our bikes, are mostly 20 to 25 years old and starting to fail on a regular basis. A purchased second-hand unit will be just as old and also likely to fail. New units do not fit the economics of running an old bike.

The advantage of Tosi's repairs is that he will fit new parts, not only to replace failed components but also the components which are likely to fail. He also soak tests on an individual basis. The ABS controllers which come back from Tosi are probably better than 'new' ones which will have been sitting on the shelf for lord knows how many years.

One last point, if you've got a faulty ABS system, disconnect the controller. Multiple faults can damage components.

GerryP makes a very important point the "new" one would likely have been made a long time ago and would be tending toward all of the age related failures due to components like capacitors drying out etc. Also a good reminder if the ABS is faulty, disconnect it until fixed by Tosi.
Regards,
K-BIKE