OK, guys, we are all contributing to confusion here. Please specify what model year you are writing about
, as this affects the problems and the troubleshooting. Early-model K12LT's will not have their ABS lights flashing due to low fluid - unless it is so low that the modulator is running empty.
The 1999-2001 LT's
(as is George's bike) feature the non-integrated ABS
system. It does not sense brake fluid level and will not throw a fault if the fluid is low in the reservoirs - unless you run out of fluid in the ABS modulator, I presume. The faults in non-integrated ABS are most likely due to self-check of the controller (signaled as controller failure) - very often caused by low battery voltage on start-up. If you are really unlucky, that is may be set as a persistent fault; there are some techniques in the archive here that purport to allow you to clear that fault yourself but these did not work for me. The dealer's computer will clear it (as, supposedly, will new version of GS-911) - even though they will try to tell you that you need a new controller. BTDT.
If you look at the electrical wiring diagram for the bike, you will see that the non-integrated ABS consists of:
- warning light relay and warning lights
- front and rear wheel sped sensors
- modulator module (confusingly called on schematics "ABS-Relay")
Nothing else. That gives you an idea of what can cause the fault. If there are no actual component failures
, the likely causes of faults are power-up controller self-check (including voltage), missing wheel rotation signal or a bad self-check at the modulator (that could be related to contaminated fluid - I do not know).
Now: sometime at 2001/2002 model year break, the integrated ABS
was introduced. It features four hydraulic circuits instead of two and additional fluid reservoirs. It is a very, very different animal to maintain and troubleshoot - but, in terms of electrical components, there is this addition:
- brake fluid level switches
Needless to say, that is the first thing to check. Also my experience with a very similar system on the GS is that integrated ABS is much more resistant to low voltage levels.
Still, with both of these systems, the basic troubleshooting includes:
- low voltage at start-up? I.e., battery nor recovering quickly after cranking?
- contamination or wrong clearance at the wheel sensors?
- contaminated fluid? Needs purging/flushing?
I do not believe that there is much more a casual mechanic can check beyond that. Next step would involve determining the actual fault code and, if needed, replacement/rebuild of the controller or the modulator - quite more of an adventure.