Honda 2004 Odyssey Service Manual page 1305

ABS/TCS Components
System Description (cont'd)
Wheel Sensor
The wheel sensors are the magnetic contactless type. As the gear pulser teeth rotate past the wheel sensor's magnetic
coil, AC current is generated. The AC frequency changes in accordance with the wheel speed. The ABS/TCS control
unit detects the wheel sensor signal frequency and thereby detects the wheel speed.
GEAR PULSER
Wheel Speed and Modulator Control (ABS)
SPEED
PRESSURE
OUTLET
VALVE
ON
OFF
INLET
VALVE ON
OFF
MOTOR
ON
OFF
When the wheel speed drops sharply below the vehicle speed, the outlet valve opens momentarily to reduce the
caliper fluid pressure. The pump motor starts at this time. As the wheel speed is restored, the inlet valve opens
momentarily to increase the caliper fluid pressure.
19-104
WHEEL SENSOR
VEHICLE SPEED
REFERENCE VEHICLE SPEED
at HIGH SPEED
at LOW SPEED
WHEEL SPEED
TIME