My statement was wrong so I deleted it.
But this I'm sure of because I took it from my owners manual.
“On ABS equipped models, the amber ABS indicator lamp begins to flash at key ON to indicate that the system is operational. It continues to flash until motorcycle speed exceeds 3 mph (5 k km/h). Continuous illumination of the lamp will only occur when ABS detects that the system is malfunctioning. In diagnostic mode, the lamp will also illuminate to indicate the presence of diagnostic trouble codes (DTCs). See a Harley-Davidson dealer for service.”