Honda Civic Service Manual page 1204

L
Wheel Soeed and Modulator Contlo
t
OUTLET
VALVE
ON
O F F
I N L E T
VALVE
ON
O F F
t\,40ToR
O N
O F F
when the wheel speed drops sharply below the vehicle speed, the inlet valve closes to retain the caliper fluid
pressure
When the wheel speed drops further, 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.
Wheel SensoJ
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 control unit detects the wheel sensor signal frequency and thereby detects
the wheel speed.
There are four wheel sensors, one for each wheel
The gear pulser has 50 teeth.
EEL SPEED
at LOW SPEED gl
=
o
GEAR PULSEB
WHEEL SENSOB
at HIGH SPEED
/
1 9 - 4 9