1997 HONDA CIVIC Start

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

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

Diagnostic Trouble Code (DTCI
Diagnostic Trouble Code {DTC) Indication
NOTE: This operation can also be carried out with the Honda pGM Tesrer.
l connect the scs service connector to the service check connector inside the passenger,s side kick panel.
2. Turn the ignition switch ON (||). but do not start the engine.NOTE: Do not depress the brake pedal when turning the ignition switch.
3 Record the brinking frequency of the ABS indicator right. The brinking frequency indicates the DTc.
4, Turn the ignition switch OFF, and remove the SCS service connector.NorE: The Mslfunction Indicator Lamp (MlL) will stay on after the engine is started if the scs service connector isconnected.
5. Erase the DTC.
Condhions for DTC indication. The vehicle is stoDDed.. The SCS service connector is connected before the ignition switch is turned ON fll).. The brake pedal is released.. Th€ SCS service connector remains connected during this procedure
The DTG indication stops 8nd the ABs conltol unit executes the softwaro tunqtion if at least one of the following condi-tions b satisfied:
o The vehicle is not stoDoed.' The ABS control unit receives the normat signal (which is for the ABS controt unit) from a Honda pGM Tester.. The SCS service connector is disconnected during this procedu.e,
u.s.A.
@
CANADA
@
SERVICE CHECKCONNECTOR {2PISCS SERVICE CONNECTOR07PAZ - 0010100
ABS INDICATOR LIGHT
DTC : 3 3
A8S INDICAIOR LIGHT
Snilion swirch
' when the ignition switch is turned oN (ll), the ABs indicator light comes on to check the bulb. Do not count it as a DTc.o The ABS control unit can memorize any number of DTCs.. The new DTC is not memorized when the ABS control unit has already memorized the same DTC,.lftheDTCisnotmemorized,theABSindicatorlightstaysONafteritgoesofffor3.6seconds.
19-56

LJDTG Erasure
1.
2.
Connect the SCS service connector to the service check connector inside the passenger's side kick panel.
Depress the brake pedal.
Turn the ignition switch oN (ll) while holding the brake pedal, but do not start the engine. The ABS indicator light
goes off after two seconds.
After the indicator light goes off, release the brake pedal The indicator lightcomeson after four seconds
After the indicator light comes on, depress the brake pedal again. The indicator light goes off again after four sec-
onds. The brake pedal is still depressed.
4.
5.
\t
6. After the jndicator light goes off, release the brake pedal again'
7. After four seconds, the indicator light blinks twice for 0 3 second and the DTC is erased
8. Confirm the DTC indication, and check that the DTC was erased
NOTE: Always maintain these steps. lf you disconnect the scs service connector and/or fail to operate the brake pedal
according to the indicator light indication, the DTC will not be erased
Conditions for DTC erasure
o The vehicle is stopped.
. The SCS service connector is connected before the ignition switch is turned ON {ll)
. The brake pedal is depressed before the ignition switch is turned ON (ll)'
. The SCS service connector remains connected during this procedure
The DTC erasure stops and ABS control unit executes the software lunction it at least one ot the following conditions is
satisfied:
o The vehicle is not stopped.
. The SCS service connector is disconnected during this servace'
.TheABscontro|unitreceivesthenormaIsigna|(whichisfortheAEscontro|unit)fromaHondaPGMTester'
. The brake pedal is not operated according to the indicator light indication
. The DTC erasure is finished
ABS INDICATOR LIGHT
OFF
DEPRESS
BRAKE PEDAL
RELEASE
0.3sec
lqnition switchoN (I)
J
19-57

Troubleshooting
The ABS indicator light does not go off after the engine is started.
- With engine running, ABSindicator light is ON.- With tho SCS sewice connec-to. connected l3oe page 19-561,no DTC is indicated,
Checkthe RR DEF RLY {7.5 A)tusein the under-dash fuse/relay box.
Raphco tha furo and rochack.
Check the ABS +B (20 A) fuse inthe under hood tuse/relay box.
R6pl.ce tho tu3c lnd r.ch.ck.
Chock for an open in the lG2 cir-GUrt:1. Turn the ignition switch ON (lt).2. Measure the voltage betweenthe ABS control unh 26P con-nector terminal No. 3 andbody ground.
Bopair opcn in tha wir. botw.cnth. RR DEF RLY 17.5 Al tus. .ndABS control unit.
Check tor an opon in thG Bl end82 circuit:Measure the voltage betweenbody ground and terminals No. 14and No. 15 individually.
Rrpair opsn in tha wiro t atwa,anthe ABS +B (20 Al fu.r .nd ABScontrol unh.
ls there banery voltage?
1To page 19-63)
ABS Indicator Light Does Not Go Off
YES NOTE: Feinstattthe luse it it is OK.
YES NOTE: Reinsta

the fuse if it is OK.ABS CONTROL UNIT 26P CONNECTOR
IG2IELK/BLUI
Wire side of female terminals
ABS CONTBOL UN]T 26P CONNECTOR
8T IWHT/GRNI
Wire side of temale terminals
19-62

Troubleshooting
Wheel Sensor
Diagnostic Trouble Gode {DTC) ll-18: Wheol S€n3ol DiagnosisNoTE: The ABS indicator light comes on when only the drive wheels are turning, signal disturbance is detected, etc. Therefore,test-drive the car at a speed of 12 mph (20 krn/h) or more after turning the ignition:witch from OFF to ON fll), and if the ABSindicator light does not come on, the svstem is OK.
0TcAppropriate Terminal(0)srDE11) SrD€r 1, 12 (Right-front)No.8: FRoNo.21: FRI13, 14 (Left-front)No. 10: FLoNo.23: FL115, 16 {Right-rear)No. {: RRoNo. 17: RRl17, 18 (Left-rear)No.6: RLoNo. 19: RLI
RLl (LT BLU}FRl (GRN/BLKI
Wire side ol female terminals
NO
NOTE:. Normal voltage: Approx.2 V' 0 V: Replace the ABS controt unit.. 4 V or more indicates a short to power.
A8S CONTROL UNIT 26P CONNECTOR
RRO
IBLU/YELI
RR1 IGRN/YELIFL1 IGRN/ORN}
- With the ignition switch ON{ll), ABS indicator tighr doe.noi go off,- Aftsr driving, ABS indicatotlight comes on.- With the SCS so.vice connac-tor conn€c,ted {soe pege 19-561,DTCs 11-18 a.e indicrted.
Chock lhe wheol sensor ci.cuit:1. Disconnect the ABS controlunit 26P connector.2. lleasure the resistancebetween the appropriate wheelsensor (0) and (1) circuit termi,
. Reprir op€n in the l0l or {0 cir-cuit wiro, or shon to thc {01 cir-cuit wi.o in thc {11 circuit wircbctween ths ABS control unitand approprieto wheel a6nsor.. R.pl.ce th€ epp.opri.te wheal3€nloa.
ls the resistance OK?
/Frontr 750 - 1050 o/20"C, 68.F \\Rear: 850- 1150 O/20.C, 68"F /
Check toru short to body groundin the wheel senso. circuit:Check for continuity between theABS control unit 26P connectorappropriate wheel sensor (0) circuit terminali and body ground.
. Rapair short to body ground inth6 (0) or lll cilcuit wi..bctwa.n th6 ABS control unitand appropdaie whoel lonsor.. Rep|'c6 tho appropriatc whcelsanlor.
Chock tor a sho.t to powe. in thowheel3en3or circuit:1. Reconnect the ABS control unit26P connector,2. Start the engine.3. Measure the voltage betweenthe ABS control unit 26P con-nector appropriate wheel sen-sor (0) circuit terminal andbody ground.
Ropair rhon to powo. in the l0lor lll circuit wire batw.en th€ABS cont.ol unit and .pplopriatawhccl !€naoa,
ls there 4 V or more?
fio page 19-65)
19-64