The VX has 3 speed sensors total on the tranny/TOD, 4 ABS sensors and a deceleration sensor on the ABS controller. The two rear ABS (L&R) sensors are only sold as a $400 set as they combine to a single connector.
Solid lit ABS light means there is a problem (short, open, etc) but the ABS system is still working. FLASHING ABS light indicates a serious problem with the system.
ABS does NOT engage until the vehicle travels above 6 MPH and automatically disengages and resets at 3 MPH.