ABS / Speedometer Problem

[mtgill]

Hello all. Been a lurker for a while, now I've got a question for the forum. Over the last few rides on my 2004 R1100S, I've been having ABS brake system failures. The events do appear to be truly random; they can occur occasionally on start up, but are also occurring part way through my ride, or sometimes not at all. Upon braking, I get a 4Hz flash on the ABS warning light and the general warning light. In most cases (city riding), I can clear the error at the next set of lights with key off, then key on. On my last three long rides (out in the country), the problem has cleared on its own. I initially assumed this was some kind of internal self correction, because I'd never actually witnessed the error clear itself; riding along and hear the brake servos stop making noise, or look at the display and see that the lights weren't flashing. On a few rides over the weekend, I was able to see the error clear... cruising at 60-70mph, the speedometer dropped to 0mph, the ABS warning light stopped flashing, then the general warning light went out. At the same time, the speedometer came back up to the correct speed. The corrections don't appear to be tied to a loose connection (the roads were very smooth, so no bumps hit to make the connection good/bad), but I wouldn't bet my $ that it's also not the problem. Looking at the wiring diagram indicates a significant number of electrical gadgets that could be the problem...any hints for key components to look at? Bike has 13,000 miles and original battery.

[sgoodwin]

Check your battery connections, fuses & the state of the battery. Sounds like replacement time may be near.

[jpramondon]

Hi there,

I don't know if you solved your problem already, but I've worked on the ABS / speedometer problems a bit to solve mines.
On the I-ABS system, the main unit (that heavy metal box under your tank) gets a signal from the sensor located on your rear wheel. Not only this signal is used to check if the weel is still spining so that the ABS can act by lowering the brake fluid pressure, but it's also computed to be sent back to the speedometer. So the rear wheel sensor is actually the speed sensor.

You should check your rear ABS sensor, or if your ABS unit is properly plugged (the huge black plug), or if your ABS wire harness is not damaged somewhere.

Hope this helps.

Cheers,

Jerome

[mtgill]

Thanks jpramondon and sgoodwin... will check the items you've suggested.