Yamaha 2007 XP500 Service Manual page 17

sure. But, if there is a tendency of the wheel to lock on a slippery road surface, due to engine braking,
the ABS may not be able to prevent the wheel from locking.
EWA15B1004
WARNING
The ABS controls only the tendency of the wheel to lock caused by applying the brakes. The
ABS cannot prevent wheel lock on slippery surfaces, such as ice, when it is caused by engine
braking, even if the ABS is operating.
EAS15B1009
ABS component functions
Wheel sensors and sensor rotors
G
Wheel sensors "1" detect the wheel rotation speed and transmit the wheel rotation signal to the ECU
(ABS).
Each wheel sensor is composed of a permanent magnet and a coil. The wheel sensors are installed
in the sensor housing for each wheel. Sensor rotors "2" are installed inside the front and rear wheel
hubs and rotate with the wheels. Each sensor rotor has 40 serrations that face the sensor housing.
As the distance changes between the top and bottom of the serrations with the rotation of the wheels,
inductive electromotive force is generated in the wheel sensors. Wheel rotation speed is detected
based on the frequency of this alternating voltage.
a. At high speed
b. At low speed
Hydraulic unit
G
The hydraulic unit "1" is composed of a hydraulic control valve (solenoid valve, flow control valve), a
buffer chamber, and a hydraulic pump for each brake and an ABS motor. The hydraulic unit adjusts
the front and rear wheel brake fluid pressure to control the wheel rotation speed according to signals
transmitted from the ECU (ABS).
c. Wheel sensor
d. Sensor rotor
1-8
FEATURES