2002 HONDA CIVIC ABS

ABS Gomponents
System Description
ABS Control Unit Inputs and Outputs for 31P Connector
Wire side of temale terminals
124567BI11121415
16111B19
20?1/t/t/l/t/
Terminal
number
Wire
color
Terminal signDescriptionMeasurement
TerminalsConditions llgnition
switch ON (ll))Voltage
BLU/
YEL
RRSDetects righfrear
wneetsensor
srgnal
;a-_-l
6-7
Wheel
Spin wheelat
I turn/second
AC: 0.053 V or
above
Oscilloscope
0.15 Vp-p or
above
GRN/
YEL
RRS (+)
BLUFRS (-)Detects right-front
wneetsensor
srgnal
5GRN/
BLK
FRS (+)
6BRN/
WHT
FLS (_)Detects left-front
wneet sensor
srgnal7BLU/
ORN
FLS {+)
8GRY/
RED
RLS HDetects left-rear
wneetsensor
srgnal
89
9YEU
RED
RLS (+)
11LT BLUDIAG KCommunications
with Honda PGM
rester
12BRNDIAG LDTC indication
19-36

Terminal
number
Wire
color
TerminalsignDescriptionMeasurement
TerminalsConditions {lgnition
switch oN lll))
Voltage
14WHT/
BLK
STOPDetects brake
switch siqnal
I4-G NDBrake pedalPressedEattery
voltaoeReleased
t5BLV
ORN
rG2Power source for
activating the
svstem
15-GNDBaftery
voltage
16BLKM-GNDGround for the
0umD motor
16-GN DBelow 0.3 V
WHT/
RED
+ B-MRPower source for
the oumD motor
17-GNDAt alltimesBattery
voltaoe
18WHT/
GRN
+ B-FSRPower source for
the valve relav
,18-GNDAt alltimesBattery
voltaoe'19BLKGNDGround for the
modulator
assemDtv
19.GNDBelow 0.3 V
20B LU/
RED
ABSDrives ABS
indicator
20-GNDABS
indicator
ONAbout 11 V
OFFBelow 1 V
BRN/
YEL
EBD(Electronic brake
distribution)
Drives brake
system indicator
21-GNDBrake system
indicator
OFFBelow 0.3 V
ON for
bulb
cnecK
8attery
voltage
(cont'd )
19-37

ABS Gomponents
System Description (cont'd)
Features
When the brake pedal is pressed during driving, the wheels can lock before the vehicle comes to a stop. In such an
event. the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is
reduced if the rear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip
rate of the wheels to ensure maximum grip force from the tires, thereby ensuring the maneuverability and stability of
the vehicle.
The ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed, then it controls the
brake fluid pressure to reach the target slip rate.
Grip Force of Tire and Road Surface
TARGET SLIP RATE
COEFFICIENT OFFRICTION
SLIP RATE
19-38

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.
Self-diagnosis Function
1. TheABScontrol unitisequippedwithamainCPUandasub-CPU.EachCPUcheckstheotherforproblems.
2. The CPUS check the circuit of the system.
3. TheABScontrol unitturns ontheABS ind icator when the unitdetectsa problem andthe unit stops th e system.
4. The self-diagnosis can be classified into these two categories:. lnitial 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)
T---
19-39

ABS Components
System Description (cont'd)
ABS Modulator
The ABS modulator consists of the inlet solenoid valves, outlet solenoid valves, reservoir, pump, pump motor, and the
damping chamber. The modulator reduces the caliper fluid pressure directly. lt is a circulating-type modulator
becausethe brakefluidcirculatesthroughthecaliper,reservoir,andthemastercylinder.Thehydrauliccontrol has
three modes: pressure intensifying, pressure retaining, and pressure reducing. The hydraulic circuit is an independent
four-channeltype, one channel for each wheel.
Pressure intensifying mode: Inletvalve open, outlel valve closed
Master cylinder fluid is pumped out to the caliper.
Pressure retaining mode: lnlet valve closed, outlet valve closed
Caliper fluid is retained by the inlet valve and outlet valve.
Pressure reducing mode: Inlet valve closed, outlet valve open
Caliper fluid flows through the outlet valve to the reservoir.
lvlotor operation mode: When starting the pressure reducing mode, the pump motor is ON.
When stopping ABS operation, the pump motor is OFF.
The caliper fluid is pumped out by the pump, through the damping chamber, to the
master cvlinder.
19-40

t
Wheel Sensors
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.
!t LOW SPEED
Wheel Speed and Modulator Control
8E!EEETqE VEJ!q!ESPEEq
5
PRESSURE
OUTLETVALVE 9p
OFF
INLETVALVE oN
OFF
MoroR I-,. ltlOFF
When the wheel speed drops sharply below the vehicle speed, the inlet valve closes and il 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.
GEAR PULSERWHEEL S€NSOR.r HIGX SPEED
19-41

ABS Gomponents
Circuit Diagram
L "*'*" lJ I5l
r**'t?lI r+l
I ^ lo+-sN
Gu csl LqF**,
"'-----
G50l
19-42

ABS Components
q,
CONNECTOR A {12P)BRAKE PEDAL POSITIONSWITCH 4P CONNECTOR
Circuit Diagram (cont'd)
UNDER-HOOD FUSE/RELAY BOX CONNECTORSCONNECTOR A {12P) CONNECTOR B {2P}
UNDER.DASH FUSE/RELAY BOX CONNECTORSCONNECTOR I {5P)CONNECTOR K I17P)MULTIPLEX CONTROLUNIT 13P CONNECTOR
CONNECTOR B I22PI
1l2l3l,/15
GAUGE ASSEMBLY CONNECTORS
CONNECTOR A I22P)
WHEEL SENSOR 2P CONNECTORS
FRONT
J --T:-l Ltqtt/)l'l L_.:-:J r\-r-----Tr'e:l
RIGHT.REAR LEFT-REAR
tslTt?t /J 1T-1\I tL | rlziJ
Terminal side of male lerminals
ABS CONTROL UNIT 3IP CONNECTOR
OATA LINK CONNECTOR {16P)
Terminal side of female terminals
Wire side of female terminals
1234567
810111213141511
123,/ ,/
67891011n213
1245678I11121415
161118192021/1,/1,/vl,/l
/t,/t/t,/t/
19-44