Makes sense, if the parts are frozen or dragging the angle sensors can't provide a proper self check . Some of the newer Honda Sport Bikes have over $6500.00 worth of brake parts , you would not want to skimp on the brake fluid changes on those units or any other complex brake system , I would do mine every year depending on the conditions, cheap insurance. Here is some tech on the system.
Modulator motor control:
The ABS control unit monitors both the two wheel speed sensors and the two modulator crank angle sensors that provide
precise readings of each modulator’s crankshaft positioning (i.e., control piston position). The ABS control unit
directs its motor driven control signals (control unit with the built-in motor driver) to deliver high-amperage electrical
output to the control motors and thus operates the system.
• Self-diagnosis function:
The dual-CPU configuration ensures instant recognition of computer-related malfunctions, since the two CPUs run constant
checks on each other whenever the ignition switch is turned to “ON.”
When the ignition switch is turned to “ON,” the ABS control unit evaluates its internal circuits. The indicator blinks
when an abnormality is detected in the system. When the system is normal, the ABS indicator stays on indicating that
the ABS control unit is in the stand-by mode for the wheel speed sensor and modulator crank angle sensor signals. The
wheel speed sensors send signals to the control unit after the motorcycle starts to move (approximately 10 km/h or
above), then the control unit evaluates the system condition by activating the modulator control motors and receiving
signals from the crank angle sensors. The ABS indicator goes off when the system is found to be normal.
The control unit monitors its main functions while the motorcycle is moving, whether the brakes are engaged or not.
When it detects a problem, the ABS indicator blinks.
• Change-over function:
When the ABS control unit detects a problem through its self-diagnosis function, it stops the ABS function. The back-up
spring in the modulator pushes the control piston automatically to open the cut-off valve and restore conventional
brake operation.
• Problem code storage function:
Problem codes can be memorized and stored in the ABS control unit (up to two codes), and can be retrieved and indicated
by the number of times the ABS indicator blinks.