Honda Civic Service Manual page 1202

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Operation
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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 it transmits the control signal to the modulator unit
solenoid valve when the slip rate is high.
The pressure reduction control is a three-mode system, that is pressure reduction, pressure retaining and pressure intensi-
fying modes.
Self -diagnosis Funqtion
The ABS control unit is equipped with a main CPU and a sub CPU, and the CPUS check each other'
The CPUs check the circuit of the svstem.
When the CPUS detect failure, they shift to the
"system down mode" or the "control inhibition mode"
The self-diagnosis can be classifield into these four categories:
O: Initial diagnosis
@: Except ABS control
@: During ABS control
@: During warning
On-board Diagnosis Funstion
The ABS control unit is connected to the data link connector {16P).
The ABS system can be diagnosed with the Honda PGM Tester.
(cont'd)
MODE ABS INDICATOR LIGHT
MAIN
RELAY
SOLENOID
VALVE
CPU
Restart condition
DTC
SYSTE IV
DOWN
O N
N o
operation
Drive
i n h i b i t i o n
Operation*r
lgnition
switch
OFF + ON
Memory
CONTROL
I N H I B I T I O N
O N
N o
operalron
Drive
inhibition
Operation
Automatic
Memory
*1: Except CPU failure
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