1996 HONDA CIVIC control unit

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

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

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

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

e\
t
ABS CONTROL UNIT 22P CONNECTOR
Wire side of female terminals
TerminalnumbelWirocororTerminalsignDe3cription
Volt.ge
ConditionE(lgnition Switch ON (ll)lOutput voltagolTqrminal namslterminils
RED/BLUFR-IN{Front-rightinlet)
Drives right-front inletsolenoid valve.
I-GNDriJ
ON-9ONOV
OFFAC: 3-6 V
OFF
/Connect the SCS servicq
connector IApprox. 3 V
BRNscs(Service checksignal)
Detects service check signal
{Diagnostic trouble codeindication)4-GND
SCS service connectorconnected.OV
SCS service connectordisconneded.Appro)(. 5 V
7BLU/RED(Warning
ramp)
Drives ABS indicator light (The
indicator light go€s off when
ABS control unit outputs bat-
tery volta9e),
7-GND
Indicator light ONApprox, 2 V
Indicator light OFFBattery voltage
8BLU/YELNot used.
10YEUBLKFL.OUT{Front-leftoutlet)
Drives left-front outletsolenoid valve.10-GNOON
ONOV
OFFAC:3-6 V
11RED/BLKFLIN{Front-l€ft inlet)
Drives left-front inlet solenoid11-GNDOFF
lconnect the SCS servicq
connector IApprox. 3 V
YEUBLU
FR.OUT(Front-right
outlet)
Drives right-front outlet
solenoid valve.12-GNO
l4LT BLUDLC(Data linkconnector)
Communicates withPGM Tester.Honda14.GNDApprox. 5 V
17BRNA/ELMCK
lMotor check)
Detects pump motor drivesrgnal.17.GNDPumpmotorreray
ONBattery voltage
OFFOV
19YELREDPMR(Pump motorreray,
Drives pump motor relay.
19-GND
ONONOV
OFFAC: 3-6 V
OFFponnect the SCS sewicq
connedor lApprox. 3 V
BLURR-OUT(Rear-right
outletl
Drives right-rear outlel
solenoid valve.
21-GNDuJ
ON
Pumpmotorrelay
ONOV
OFFAC: 3-6 V
OFF
lconnect the SCS servicq
connedor )Approx. 3 V
22BLKGND2(Ground 2)Ground for the ABS controluntt.22-GNDBelow 0.3 v
19-53

Troubleshooting Precautions
ABS Indicator Light
I The ABS indicator light comes on when the ABS control unit detects a problem in the system. However, even thoughthe system is normal, the ABs indicator light can come on, too, under the following conditions. To determine theactual cause of the problem, question the customer about the problem, taking the following conditions into consider-ation.
. Signal disturbance
. Wheel soin
. Only drive wheels rotate. Battery voltage fluctuates
2. When a problem is detected and the ABS indicator light comes on, the indicator light can stay on untat the ignitionswitch is turned off, or it can automatically go off, depending on the mode.. Lightstayson until the ignition switch isturned off;When the system is inthesvstem down mode.o Light automatically goes off:When the system is in the control inhibition mode.(refer to symptom-to-system chart)3 The ABS indicator light stays on when the system is reactivated without erasing the DTC, but it goes off after startingthe car.
when the wheel sensor system is faulty and the ABS indicator light comes on, the algorithm of the system automaticallyturns off the ABS indicator light after the wheel speed signal returns to the normal speed. while, when the DTC is erased,the CPU is reset and the ABS indicator light goes off when the system check€d out normal by the initial diagnosis.Therefore, test-drive the car after servicing the wheel sensor system, and be sure that the ABS indicator light does notcome on.
4. When the ABS control unit outputs battery voltage to the gauge assembty, the ABS indicator light goes off.
Diagnostic Trouble Code (DTC)
1. The diagnostic trouble code (DTC) is memorized when a problem is detected and the ABS indicator light does not gooff, or when the ABS indicator light comes on.The DTC is not memorized when the ABs indicator right comes on unress the cpU is activated.2. The memory can hold any number of DTCs. However, when the same DTc is detected twice or more, the later one iswritten over the old one.
Therefore. when the same problem is detected repeatedly, it is recorded as one DTC.3. The DTCS are indicated in the order of ascending number, not in the order thev occur.4. The DTCS are memorized in the EEpROM {non-volatile memorv}.Therefore, the memorized DTCS cannot be canceled by disconnecting the battery. perform the specified orocedures toerase.
Solf-diagnosis
1. The self-diagnosis can be classifield into these four categories:' Initial diagnosis; Performed right after the engine sta rts and untiltheABs indicator light goes off.o Except ABS control: Performed when the ABS is not functioning,. During ABS control: Performed when the ABS is functioning.. During warning: Performed when the ABS indicator light is ON.2 The system performs the following controls when a problem is detected by the self-diagnosis:. ABS indicator light ON. Memory of DTC
. Mode change to the "system down mode,, or the "control inhibition mode,,.
MODEABS INDICATOR LIGHTMAIN
RELAY
SOLENOID
VALVECPURestart conditionDTC
SYSTEM
DOWNONNo
operal|on
Drive
inhibitionOperation+rlgnition
switchOFF - ONMemory
CONTROL
INHIBITIONONNo
operat|on
Orive
inhibitionOperationAutomaticMemory
*1: Except CPU failure
19-54

tJ
t\
Kickback
1. The motor operates when the ABS is functioning, and the fluid in the reservoir is forced out to the master cylinder
causing kickback at the brake pedal.
2. TheABScontrol unit operates the solenoid valve when the brake pedal is released afterthe initial diagnosis Youmay
hear the faint solenoid valve operation sound at this time. but it is normal.
Pump Motor
1. The pump motor operates when the ABS is functioning
2. The ABS control unit checks the pump motor operation during acceleration. You may hear the faint operation sound
at this time. but it is normal.
Brake Fluid Replacament/Air Blsading
1. Brake fluid replacement and air bleeding procedures are the same as for conventional brakes
Troubleshooting
1. The troubleshooting flowcharts explain the procedures on the assumption that the cause of the problem is still pre-
sent and the ABS indicator light is still on.
Note that troubleshooting following the flowchart when the ABS indicator light does not come on can result in incor-
rect judgment.
2. Ouestion the customer about the conditions when the problem occurred, and try to reproduce the same conditions
for troubleshooting.
self,diagnosis is made at various times such as the initial diagnosis, except ABS control. during ABS control, during
acceleraiion, during the specified vehicle speed, etc. Therefore, the symptom cannot be checked unless the check
conditions match with the problem conditions
3. When the ABS indicator light does not come on during the test drive, but the troubleshooting is performed based on
the DTC, check for the loose connectors. poor contact of the terminals, etc, before troubleshooting.
4. After troubleshooting, erase the DTC and test-drive the car. Be sure that the ABS indicator light does not come on.
5. The connector illustrations show the female connectors with a single outline and the male connectors with a double
ouflrne.
6. The connector terminal cavities containing female terminals are always numbered by looking at the connector from
the wire side. and the cavities containing male terminals are always numbered by looking at the connector from the
terminal side.
r'
19-55