Hi all. First time post after a lot of shadowy reading. New to me k1200gt yesterday threw a cruveball. 6 hour ride with no issues, but about 10 metres from home the abs warning triangle was solid and brake failure fast flashing. Manual says one or both circuits not receiving brake assist which was true, the back brake was cactus, front still fine.
Turned off bike then ignition on without starting and the abs did its little check, all as usual. But about 10 more seconds and the lights start blinking again and the servo motor can be heard making erratic whizzing without brakes applied. Checked the microswitches on the levers and they weren't faulty/stuck open.
Anyway, put the bike away with a trickle charger and in the morning, no issues. Rode around a bit still nothing. Battery test at a shop said all good, but charging was only 13.4V even at high rpm. Should be high 13s correct?.
So! Bad abs unit? Or abs just playing up because of low voltage? If so, hopefully not an alternator change.
Thanks all for reading. Loving the new 1200 but I miss my 1100lt every day.
A good / strong Battery is critical to all BMW models having iABS modulator (ABS with whizzy servo motors). The Battery is NOT the most common issue, but it becomes difficult to troubleshoot (at a distance) if this part of the system is not perfect. The Modulator pulls a lot of AMPS when both internal motors run (front + rear automatically applied when front lever is pressed), thus at idle when the Alternator cannot furnish its max output, the battery is the buffer / supplier. Of course over 2000 RPM, the Alternator can keep up (840 watts capacity).
Normally, for K1200RS/GT with "brick-engine" the charging voltage read at battery pole should be "roughly" 13.4 to 14 volts at idle - a bit more at 2000 RPM (more like 13.6 min to 14.5 max). Do not forget that a "hobby" Voltmeter can easily have a 4% error so make sure to check with another one to confirm. DID YOU CHECK for any loose or dirty connection at battery POLES ? This can affect reading / supply.
Most problems of these iABS modulator are caused by lack of usage (bike parked for 1 year or more) combined by lack of flushing / replacing the DOT4 as recommended by schedule. Storage temperature / conditions when parked will also add to the equation... I see many K1200RS and K1200GT being sold for very low amount on the market - unfortunatly many have been parked much too often and did not get the brake maintenance they should have (max of 2 years between flush using the complex procedure as per BMW shop manual).
I AM ASSUMING you HAVE ALSO CHECKED fluid level in BOTH SECTIONS of the small reservoir located on right side (just below radiator expansion tank). Note that brake fluid level goes down with brake pads wear.
HOWEVER, given your symptoms above, there is a much higher probability you will get one of these internal fault codes - in such case it is often the end for your ABS modulator:
1) code 17419: Rear ABS motor defective
2) code 17433: Pressure in rear wheel cylinder too low
In your case, to confirm type of fault, I would suggest you find someone with a GS-911 to read which ABS fault codes you have. Your BMW dealer can also read these codes for $$.
If the news are not good (as I suspect), then contact Module-Master in Idaho. Although their web page still says
"This rebuild is currently UNDER DEVELOPMENT..." recently a friend was told they had just started repairing these iABS modulators, BUT apparently they are backlogged for a long time on these repairs.