Wheel Sensors - Honda Civic 2002-2003 Service Manual

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Wheel Sensors
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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 ASS control unit
detects the wheel sensor signal frequency and thereby detects the wheel speed.
GEAR PULSER
O~
_t HIGH SPEED
.t
lOW SPEED
Wheel Speed and Modulator Control
SPEED VEHICLE SPEeD
REFERENCE VEHICLE
SPE~JL
WHEEL SPEED
TIME
PRESSURElLl0~
.
.::====:::::::~_....::======:::::~~.
_.......:::::::=
OUTLET
t
VALVE 0::
L--' . O...J... ______ -.JO....L __________ ..lO....L_
INLET
t
VALVE ON
I
n
I I 0 I
OFF L_-L _________
~~
________________ LLLL ______ _
MOTOR ONt
OFF
~L-
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
When the wheel speed drops sharply below the vehicle speed, the inlet valve closes and if necessary, the outlet valve
opens momentarily to reduce the caliper fluid pressure. The pump motor starts at this time. As the wheel speed is
restored, and the outlet valve closes, the inlet valve opens momentarily to increase the caliper fluid pressure .
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