ABS pump/module failure
 

Is it common the have ABSpum/module failure in early 2003 R 1100 S Boxercup edition bikes? How much to replace the part?

Think of it as a chance to both improve braking & eliminate 15 lbs. of weight up high. Remove that crap & enjoy great brakes. There's an abundance of posts on removing it from the newer models which unfortunately is a bit more complicated because the speedo runs off the ABS.

+1 for the ABS ectomy. Replace the rubber brake lines with SS braided and you’ll have better brake feel and never worry about the stupid ABS again. Modern ABS is wonderful, much safer and better than humans can stop you but the ABS in these bikes sucks and can cost more than the bike is worth to fix. Substitute a Lithium Ion battery for the lead weight and your bike will be ~ 23 pounds lighter up top.

Yep, done all 3 & it makes a huge difference in stopping feel with steel braided lines & turn in with all that weight up high gone. My odyssey battery was 16 lbs. vs. under 2 for the Deltran lithium battery. More like 29 lbs. gone. in my case.

Don't know which unit you have but it's about $1,000 in US dollars .

https://rhelectronics.de/repair/units/motorcycle/abs-motorcycle-am/?lang=en