speedometer sensor

2007 K1200GT w/ABS. Recently the brake failure light flashes while riding. I braked hard a couple of times when I saw it and there doesn't appear to be any brake issues. The speedometer needle dropped to zero several times on my last ride. Could this be a sensor, wiring harness or connector...

I'm thinking spedo sensor is dirty or getting wonky ? I fired up my 1995 k75 for nice long ride today . Bike fired right up and ran perfectly as it always does ... But approx 1 minute after starting the bike , while it sat idling , over the course of 10 secs I saw the spedo move from 0 to 10 mph...