When you turn your key to the on position you should see the ABS light for an indication that the light is working. Then the light should go out after a short time or after the engine has started.
The ABS computer looks to see the sensors are active. When the bike rolls the computer sees both the wheel sensors and light will indicate if there is a problem or activate the system to compensate for difference in braking. Typically, The ABS pump activates when there is a percentage of error in rotation between the one of the wheels. This only senses difference in rotation but does not sense lateral forces on the wheels. ABS can only compensate so much. It is important when trying to trouble shoot a failure of the ABS system to understand that ABS is not technology that can prevent all of the possibilities present to the front wheel. There are many more forces at play on a motorcycle than on a car that will cause it to go down.
Also there are single channel and dual channel ABS systems, The latter are more sophisticated at controlling wheel lock up. Another factor might be service and having new fluid in the system.
