When I bought my "wrecked" 2010 ST1300, the ABS light wouldn't go out at all! I even took it into the dealer (still under warranty), and after replacing the front sensor and the light not going out, they told me they think it was the ABS ECU, but the only way they could find out was for me to buy a new one (at $1,100) and if that fixed the issue, they would send the broken one in to Honda and see if they would cover it. And because of the accident the bike was in, that was questionable!
A few months later, I found one on ebay from a wrecked cop bike with only 409 miles on it. I picked it up for less than 25% of a new one. And yes, it fixed my problem. That was almost a year ago and the light continues to work correctly!