I own a K1100LT with ABS1 v2.5. Last year I had to reset it three times. This year when I put the bike back on the road the ABS would no longer reset.

Perceived wisdom seemed to be to put tape over the flashing lights and ride it until you can afford to get it repaired. Which I did.

About three months ago on my way to a friend in Somerset the bike cut dead. No warnings and of course, in the middle of nowhere. This turned out to be a flat battery. I phoned my friend, he bought out a charged battery and I finished the journey (just).

Poking around in his garage I found the flat battery had been caused by a dead regulator on the alternator, hence no idiot light warning. I charged my battery and forgot about the problem for the weekend.

I went home on the coach, purchased a s/h 50A alternator on fleabite and returned the next weekend to fit it. Rode the bike home - end of story, or so I thought.

At the start of this month I decided to try to fix the ABS controller (I was periphally involved in the design of this sort of thing in my youth). With all due precautions I opened the case, took one look and put it back together again.

There is only one person who has any expertise on these units so I got in touch with Tosi Tabuki in Japan and he agreed to try to fix it. Off it went and very quickly Tosi had analysed the faults and fixed all five of them. The quantity of faults was unusual, he said, normally there would only be one. So it is possible I may have damaged the unit further by continuing to ride with it.

While the soak test was happening he said, "I would like to have your attention on the condition of your K11 because your ECU has defective at the circuit related to error 1,2 and 6 at the same time. this condition possibly lead to a lot of current draw because ABS relay and modulator are active simultaneously and will continue to do so as long as the ignition is on and battery can hold the current. that could cause the wiring from battery to ABS relay to modulator were toasted and the modulators were damaged. I recommend you to check those wiring before you install repaired ECU on the K."

One of the things I had noticed when I broke down in Somerset was that the rear ABS modulator was quite warm. So in retrospect it looks as though the simultaneous 1,2,6 ABS error fault may have cooked the regulator on the old 32 amp alternator causing the battery to flatten and stranding me.

It also leaves me a good deal of component and wiring checks to do before I refit the ABS controller.

So in conclusion my advice would be to remove the ABS controller if it fails. This stops the idiot lights flashing and allows the bulb warning device to operate properly. It may also avoid a long walk.

I also heartily recommend Tosi Tabuki's service fixing these things, he's quick, his prices are reasonable and he emails progress updates regularly.

His website is http://bmwk10075abs1fix.web.fc2.com/index.html

Well done on the diagnosis and keep at it you will get through Tosi is a great guy who provides a great service fixing these ABS units and for a very reasonable price compared to buying an unknown quality S/H unit or pricing a new one

Could not recommend him more strongly he fixed ABS really quickly and it is now perfect.
Regards,
K-BIKE

Thanks K-Bike.

Just to finish up the story. After a two nasty shocks from the government and the mail company which added 40UKP to the bill I received the ABS controller back and fitted it.

The self diagnostics told me that indeed the rear ABS modulator was toast. So I hit Fleabay again for a second-hand replacement, fitted it and wonders, it all worked!

Was it worth it?

My personal experience of ABS is that it triggers when I'm not expecting it. Ie. when I've overestimated the available grip. The alternative being an interesting slide and a trip home to change my undies.

In addition I suffer under the ancient engineer's curse, 'If its fitted, its bloody well going to work.'

GerryP wrote:Thanks K-Bike.

Just to finish up the story. After a two nasty shocks from the government and the mail company which added 40UKP to the bill I received the ABS controller back and fitted it.

The self diagnostics told me that indeed the rear ABS modulator was toast. So I hit Fleabay again for a second-hand replacement, fitted it and wonders, it all worked!

Was it worth it?

My personal experience of ABS is that it triggers when I'm not expecting it. Ie. when I've overestimated the available grip. The alternative being an interesting slide and a trip home to change my undies.

In addition I suffer under the ancient engineer's curse, 'If its fitted, its bloody well going to work.'

Great thread Gerry, and good advice on disconnecting the brain, thanks. I had the same obsession with my ABS. If I'd bought a bike without ABS I'd have no inclination to fit it and I certainly did not actively seek one with ABS. But as it was there it HAD to work and at this stage in teh season I'm quite happy to have it. How did you get on bleeding the system after replacing the modulator?

BTW like your artwork
Cheers
Dave

Thanks Dave, glad you liked the pictures.

Bleeding the modulator/rear caliper wasn't too difficult.

I found the proverbial pickle jar with a steel lid and punched three holes in the lid with the BMW philips screwdriver. Hit up Halfords for some dot 4 and a couple of meters of nylon washer tubing which I cut to length and poked through two of the holes. This stops the tubing popping out of the jar all the time. Loosened the bleed nipples with a ring spanner and pushed the tubing over the bleed nipples.

I used a luggage strap to secure the reservoir where I could get at it.

Then its just a case of; push - open - pause - close - release - pause for the next half hour or so. I like to apply pressure to the fluid by pressing on the brake lever in question and then opening the bleed nipple as quickly as possible. The theory is that this helps to jolt the bubbles free. A few taps with the spanner does no harm either.

I worked on the Modulater first and most of the air came out of it. Then on to the caliper and repeat for each a couple of times until no bubbles were visible. Actually none came out of the caliper 'cos I hadn't drained the system.

I suppose it took about an hour and a quarter pint of dot 4 to do that part of the job.

There is no point going for a rock-solid pedal feel, the rear brakes on these bikes are deliberately soft in feel so they will not be so easily locked up.