Check your battery first, then all connectors. Try a hard reset: holding +ve and -ve leads together for 30sec when disconnected from the battery, this removes any stored capacitance in the system.

Others on here know more about the early K 'whizzy" brakes.

 

thanks Erik - will give the reset a shot - crossing fingers its a fix 🙏

 

Don't know if it will fix it, but this does reset things.

Battery should have at least 12.3v at rest.

Your era of K1200 is renowned for ABS failures, there is plenty of info on here if uou search for K1200 ABS or "ABSectomy" or similar keywords. Brakes work fine without ABS on these bikes btw.

 

Sadly the reset didn't work (disconnected both battery leads, connected them for 30 seconds, and left the battery leads disconnected for 24 hours) - next step is to see if i can get my hands on a wiring diagram for the connector so i can find whether one of the pins is damaged and causing the outage - so far no luck with google - will check with one of the better dealers to see if they can direct me to one

 

Wondering whether anyone has experienced anything similar and what they did to get it functioning again - some additional tidbits of info...

I did. Water ingress destroyed the PCB. BMW screwed up with the gasket for the computer on the ABS unit, and it fails, and water gets in. For those who still have a working unit, I would add this to the to-do list to keep them running.

I replaced it with a different PCB from some parts ABS, reprogrammed it in ISTA, and that worked, until water got into the motors for the pumps or something. I went through some troubleshooting process, but drew a line when I saw a guy hook a scope up to the pressure sensors. I capitulated and removed the ABS (fashioned a case for the ECU, and siliconed that shut. Make sure to use electronic compatible silicone, b/c I fried another PCB using regular silicone that leeched acetic acid onto the electronics and fried it).

I have a thread detailing this somewhere.

 

If this ABS is similar to my older bike ABSII, I shall spend more time looking at it now it's off the bike. I guess you kept the board for the speedo? I don't have EVO and if I decide to remove it completely, I might build an interface board for the speedo. I think my problem is swollen piston seals and finding substitutes in compatible rubber may be hard.

 

Ok - figured it out - another rookie mistake - I had disconnected the rear abs sensor connector from the wiring harness - disconnecting this sensor essentially eliminates all signals going thru the ABS system, the servos, the brake light. Kinda crazy setup IMHO.

now onto the next step and see whether I can complete the bleed of the ABS pump and get all the brake settings back to normal again

silver lining - learned a lot in the process - how to back probe connectors and wiring, how to follow a wiring diagram (shout out to Prosperos Garage for getting me a great set of diagrams), how to understand what the darned CAN Bus system does