Honda Civic 2002-2003 Service Manual page 633

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ABS Control Unit
Main Control
The ABS control unit detects the wheel speed based on the wheel sensor signal it received, then it calculates the
vehicle speed based on the detected wheel speed. The control unit detects the vehicle speed during deceleration
based on the rate of deceleration.
The ABS control unit calculates the slip rate of each wheel and transmits the control signal to the modulator unit
solenoid valve when the slip rate is high.
The pressure reduction control has three modes: pressure reducing, pressure retaining, and pressure intensifying.
ABS CONTROL UNIT
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I DETECT
r
VEHICLE SPEED
I
REFERENCE
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SLIP RATE
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I I
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REAR
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I .:m~r-~~~~OR DETECT
:::;l
fL~~~~E
ASS
l S~~'i'~OID RIGHT.REAR
I
WHEEL SPEED CONTROL SOLENOID
I I
I
I
I
LEFT-REAR
W~~~~WPEED
t-
~ SELECT LOW
r-:
DRIVE
LEFT-REAR
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WHEEL SENSOR SPEEOWHEEL SOLENOID
SOLENOID
I I
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RIGHT ·FRONT
I
I
RIGtfT·FRONT
DETECT
~ Jt~~~~\E
--::
ASS DRIVE
~grlN"J'lgNT
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WHEEL SENSOR
I
WHEEL SPEED CONTROL SOLENOID
I
I
I
LEFT-FRONT
I
I
LEFT·FRONT
DETECT
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ASS DRIVE lEFT-FRONT
I
WHEEL SENSOR
WHEEL SPEED
CONTROL SOLENOID SOLENOID
L ___________________________ J
Self-diagnosis
Function
1. The ABS control unit is equipped with a main CPU and a sub-CPU. Each CPU checks the other for problems.
2. The CPUs check the circuit of the system.
3. The ABS control unit turns on the ABS indicator when the unit detects a problem and the unit stops the system.
4. The self-diagnosis can be classified into these two categories:
Initial diagnosis
• Regular diagnosis
On-board Diagnosis Function
The ABS can be diagnosed with the Honda PGM Tester.
The ALB Checker cannot be used with this system. For air bleeding and checking wheel sensor signals, use the Honda
PGM Tester. See the Honda PGM Tester user's manual for specific operating instructions.
(cont'd)
19-39