1999 HONDA CIVIC ect

Component Locations
ta
SERVICE CHECK CONNECTOR {2PIBIGHT.REAR WHEELSENSOR CONNECTORMOOULATOR UNITABS CONTROL UNIT
RIGHT-REAR WHEEL SENSOR
LEFT.R€AR WHEELSENSOR CONNECTOR
J
UNDER.DASH FUSE/RELAY 8OX
LEFT.FRONT WHEEL SENSOR
ABS +B (20 A) FUSE
UNDER.HOOD FUSE/RELAY BOX
lcl lilo Al FUSE
ABS INDICATOR LIGHT
UNOEF.DASI{ FUSE/RELAY BOX
HORN/STOP I15 A) FUSE
UNDER.HOOO ABS FUSE/RELAY BOX
PUMP MOTOR {'O A} FUSE
PUMP MOTOR BELAY
E
o
METEB I7.5 AI FUSE
0
0
0
00000 n
00000 u
BR DEF RLY 17,5 A) FUSE
t
MTR CHECK (7.5 AI FUSE
19-45

Anti-lock Brake System (ABSI
Featu res/Construction
When the brake pedal is depressed during driving, the wheels can lock before the vehicle comes to a stop, In such a case,the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if therear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip rate of the wheels toensure the grip force of the tires. and it thereby ensures the maneuverbility and stability of the vehicle.Judging the vehicle speed. 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 attain the target slip rate.
Grip Force of Tire and Road Surlace
COEFFICIENT OFFRICTION
TARGET SLIP RATE
Slip Rate
BRAKINGSTART POINT
ROTATIONALDIRECTION
RADIALDIRECTIONOF THEROTATIONALOIRECTION
A: Distance without slio8: Slippsd distanceC: Actuel distance
sr-rrmre=f=SLIP RATEVEIIICLE SPEED - WHEEL SPEEOVEHICLE SPEED
19-46

t-Operation
t
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)
MODEABS INDICATOR LIGHTMAIN
RELAY
SOLENOID
VALVECPURestart conditionDTC
SYSTE IV
DOWNONNo
operation
Drive
inhibitionOperation*rlgnition
switchOFF + ONMemory
CONTROL
INHIBITIONONNo
operalron
Drive
inhibitionOperationAutomaticMemory
*1: Except CPU failure
/
19-47

Anti-lock Brake System {ABS)
Operation (cont'dl
ABS Modulator
The ABS modulator consists of the inlet solenoid valve, outlet solenoid valve, reservoir, pump, pump motor and thedamping chamber.
The modulator reduces the caliper fluid pressure directly, and it is also referred to as a circulating type because the brake fluidcirculates through the caliper, reservoir and the master cylinder.The hydraulic control has three modes: pressure reducing, pressure retaining, and pressure intensifying.The hydraulic circuit is the independent four channel type, one channel for each wheel.
RF LR
Pressure intensifying mode: Inlet valve open, outlet valve closed
Pressure retaining mode:
Pressure reducing mode:
Motor operation mode:
rN: INLETVALVE {NORMALtY OpENIOUT: OUTIET VALVE {NORMALIY CTOSED)Master cylinder fluid is pumped out to the caliDer.Inlet valve closed, outlet valve closedCaliper fluid is retained by the inlet valve and outlet valve.Inlet valve closed, outlet valve oDenCaliper fluid flows through the outlet valve to the reservoir.When starting the pressure reducing mode, the pump motor is ON.When stopping ABS operation, the pump motor is OFF.The reservoir fluid is pumped out by the pump, through the damping chamber, to the mastercvlinder.
PUMP MOTOR
19-48

L
Wheel Soeed and Modulator Contlo
t
OUTLETVALVE ON
OFF
INLETVALVE ON
OFF
t\,40ToR
ON
OFF
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 SPEEDgl
=o
GEAR PULSEBWHEEL SENSOBat HIGH SPEED
/
19-49

Gircuit Diagram
MOOULATOR UNIT IOP CONNECTOR
zrJrF!_lll 2 3ll
14TiEltl
c@4
PIMP MOTOR 2P CONNECTOR(Ll number)fFlGTN
UNDER.HOOO A8S FUSE,/FELAY BOX3P CONNECTOR (O number)
| 2 3l
UNDER.HOOD AAS FUSE/RELAY BOX2P CONNECTOR (! number)
| -l
GAUGE ASSEMELY 5P CONNECTOR
---t--t1 t/ 13 )/l5l
Wire side ot temale terminals
- E8l{'Ytr
AA DEF BLY I7.5AI
_@f_u,
n4@f-n,
LEFT.FSONT SOLENOIO
UNDER-OASH FUSSRELAY 8OXZoP CONNECTOR (O numbe,
235678It0tlt3/ i15 /t820
UNDER.OASH FUSE,/RELAY BOX18P CONNECTOR (E numb€r)
23569ll213)t4 /1617
19-50

tABS CONIROL UN]TECM / PCMISCS'
V
,,, +-{l-, ?,,] B6li! [,b.,,,,,-F-
SENSOR
+B
YWHTNED
8U(
J-
G,Ol, Ga02
l
\EWIK
LEFT.
RIGHT,
LEFT
;___.|-1
**1. ,I
coierou
SERVICE CHECKCONNECTOR (2P}
lrl2f
OATA LINKCONNECTOR O 6P)
WHEEL SENSOR2P CONNECTOB
FRONT
/.[Ttl\
REAR
tc-T-lI zlr[B'1213
ABS CONTROL UNIT 26P CONNECTOR1O numb€r)
12346/8Il0./ tt12r3
14 t516 1719 ,/2123
-o&"^1'
cot, croz
Terminalside ofmale terminals
ABS CONTROL UNIT 22P CONNECTOR1! numb€r)
/Wire side of female terminals
19-51

ABS Control Unit Terminal Arrangement
ABS CONTROL UNIT 26P CONNECTOR
Wire side of temale terminals
Terminalnumo0rWirecolorTerminal signTerminalnamoDgscriptionVoltage
Conditions(lgnition Switch ON flt))Output voltagoteminals
PCOM(Primary
common)
Power source for the solenoidvalve and pump motor.1-GNDON
=ONOV
AC: 3-6 V
BLK/WHTscoM(Secondary
common)
Power source for the solenoid
2.GNDOFF
lConnect the SCS service\
conneclor lApprox. 3 V
ELVBLUtG2(lgnition 2)Detects ignition switch 2
!9nal. (system activate signal)3-GNDBatt€ry voltage
BLU/YELRRO(Rear-right 0)Detects right-rear wheelsensor signal.4-17
When the wheel isturned at 1 turn/second.
53 mV or above ondigitaltester (ACra nge) {Fefera nce)150 mvp-p or aboveon oscilloscope
6GRYRLO(Rear-left 0)Detects left-rear wheel sensorsrgnal.6-19
8GRNFRO(Front-right 0)D€tects right-front wheelsgnsor srgnal,a-21StopsApprox.2.5VSTOP(Stop)hects brake switch signal.(Prevents unnecess€ry ABS operation)9-GNDBrake pedal depressed.Battery voltage
Brake pedal released.OV
10BRN^/vHTFLO(Front-left 0)
Detects left-front wheel sensorsignal.
10-23
When the wheel isturned at 1 turn/secono.
53 mV or above ondigitaltester (ACrange) (Referance)
150 mVFporaboveon oscilloscope
9!opsApprox. 2.5 V
12YELRLOUT(Rearjeft outlet)
Drives left-rear outlet solenoid
12.GNDON-9ONOV
OFFAC: 3^6 V
REDMHTRR]N(Rear-right
inlet)
Drives right-rear inlet solenoidvalve.13-GNDOFF
lconnect the SCS service]i connector IApprox. 3 V
14B1(Battery 1)Power source for the solenoidvatve and pump motor.14.GND
Battery voltage15WHT/G R N82(Baftery 2)Power source for the solenoidvarve ano pump motor.15.GND
r6BLKGND2{Ground 2)Ground for the ABS controlunit.16-GNDBelow 0.3 V
17GRN/'/ELRR1(Rear-right 1)Detects right-rear wheelsensor signal.17-4
When the wheel is turnedat 1 turn/second.
53 mV or aboveon digitaltester(AC range)(Referance) 150mVp-p or aboveon oscilloscope
19LT BLURLl(Rea.-left 1)Detects left-rear wheel sensorsagnal.19-6
GRN/BLKFRl(Front-right 1)Detects right-front wheelsensor signal.21-8
FL1(Front-left 1)Detects left-front wheel sensorsignal.23-10StopsApprox. 2.5 V
REDRL-IN(Rear-lett inletl
Drives left-r€ar inlet solenoid
25.GND
ut
ON
'6
-9ONOV
OFFAC: 3-6 V
OFF
lconnect the SCS service] connector lApprox. 3 V
BLKGND3(Ground 3)Ground for the ABS cgntrolunit.26.GNDBelow 0.3 V
19-52