1996 HONDA CIVIC o2 sensor

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

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
Symptom-to-System Chart
DTC
oH1=DIAGNOSIS/SYMPTOM
DETECTION TIMING
>=PNOBABLE CAUSEi.'sEV98€E
zr\9=6<_6
=t
6tz
NODTC
ABS indicator iighr doesnot com€ on when ignirionswrt.h is lu.ned on (ll)
, Open in the pow€. source circ!ir ror the ABS -.ndicato;l isht. Elown ABS indicalo.lighr butb' Open in rhe ABS indicaror tight drive cncuit.. Shori ro pow€r in theWALpcircuit. FaultyABS contrct!nit
ONABS indicator light doesnol90 oft 6frer engine isOpen in the lG2 circuitOpon in the +B circuirOp€n andlor short ro body ground jn the WALP circuitFaultv AAS coni.ol unnt1
oN.Wheel sensor (op€n/shortOooo13upen, snofiro bodyground and/or shodro power in rhe wh€61
Faulty ABS co.lrctunitllBL12
oN.(chipp€d pulser gea/noise)oao
Short to wh6sls€n6or (O)circuir in t'e.h;;Go-nso, trtcircutiFaulty whsel s€nsor insra|ation
Faulty ABS cont.olunir
I8
31
ONSolenoid (open/shon roaoa
Op.ni shon to bodyground and/o. shorrto powsr in rhe
op€n in lh6 coM circuit
Faulty ABS conlrclunit
32F8-OUTFL.IN3'lFT.OUTRF.IN88 OUT318t rN38RLOUT
ONoo
op€n in tho motor pow€..ourco circliaOp€n inih€ moro.cNOcircuit
Faulty ABS conrrol unit
52ONoo
Open in rh€ COM, PMR 6nd/o. MCKcircuirOp€n.n.Vor blown lus€ in the under hood AgS rusdretry box
Faufty pump moto. rotayfaulv ABS conlrolunit
53ONo
. Sho.tto bodygrou.d in the pMR circuit. Shon to powsr in tha puhp moror pow6rsource circu. r.urty pump motor.etay, FalltyABS contolunit
54ONooc
Open, rhorr ro bodygrcund and/or blown fus€ in the B1 or 82
Shonto body ground.n.Vor short to powor in rhe COM circuitFaulty modul.tor unnFaulty ABS controt unit
ONlgnition voltage (low vott-oooo
. Connection ot the24 V bariorv tor enqins starr. Faurtycharoins system. Op€n in th6lG2 circuit. Fa!lly ABS contrcl unil
81ONCPUoooo
E {€rml facior{sl en bs rhe ouse{sl ot |he probtemF.ulty ABS conrrot unit
r: It DTcs 1 1 18 {wheel sensor codes) wore del*ted the lasr time the v6h cls wEs d riv€n, rhe a8s indicator tight wi

stay on u ntit lh6 ignition swirch is rurn6d oN t), and theconnorunit contnms rhat rhe wheet sensoB . rc OK,
19-58

Le
\.t
CONDITION FOR DETECTION
MANAGEI\,4ENT
FEFERTOPAGEDUNINGABS CONTFOLEXCEPTABS CONTAOL
19-60
19-62
The ABS indicator lighl cones on when vehicle is stopp€d and wheel sensor a given vohaqe does nol
19 64
The ABS indicaror comes on under th€lollowing conditions.When morethan one otwheels are a standstiland thelelocirv otthe fastest wheel reaches a
' fohen th. velocity of the faslesl wheel reaches or exceds a given sped, and it there ar€ somewh@lswhose velocity is slowe.lhan a cenain percenlage oi lh€ fast6t wheelsped for 3 given period. when rhere are lemporary open or short ctcuits ol rhe wheel sonsor' chipp€d pulser gear, orsrgnalorslJrbaaLe
19 64
The main relay repeats ON/OFF switching atalltimes.WhenthemainrelayisON,ashortt$tpulseissentloeachvalve lfthere s some dis'repa ncv, lheABS indicalor lightcomes on.. When rhe main relay is OFF, a shonl€sl pulse is s€nlto each valve lfth6 solenoid drive voltage rsout ol a qiven range, the ABS ndicalor lighl comes on19-66
'The pump nolot s activaled orc€ o' Mrce sfier every gn't'on sw'lch ON (ll) operarion whrle lte -^vchicle acLelerales lrenthemolorotivevo'taSersrhecled When lhevolla96 rs abnormar,lre Absindicaror llghl comes on.. Afte. ABS ;onl rol com pletion, the moror isswitched ofi 6nd the main CPU checks the molor dnvevoltase. when rhe vortase is abnormsl, the ABS indicato49!!!99!:l!:_-
19-68
D!rino an active motor lesl or AAS control,lhe main CPU checks ihe supplv voltage to the motor'whe;lhe vohage s abnofmal, the ABS indicator lightcomes on19,68
lirhe moror drvevoltage indicates molot operalion when the main cPU does notswilch the motoroN, rhe ABs indicaro. comes on19-64
. Wh"" " ".1"".1d ""1r. f"llure is detecred, the CPU checksth€ voltage ofthe main rel6v output lllhevohaqe is lowerthan 6 given vohage, theABS indicator light comes on. The ;ain r€lay repeats ON/OFF switching ar a!ltimss when the main rel.v is ofi, a shorl l6st pulse
is sent ro €ach valve. The CPU mon tors the reJer€nce vohage ll the vohage is out ot a g iven range'
the ABS indic.tor lightcomes on
19 71
wt'",, rt'e lgnitlon rottag" is ower or higherthan a given voltage,lhe CPU inhibils ABSlonlrolandswirches oli the ma in relaY, 6nd the ABS indicaror lig ht com€s on When the ig n ilion vohage recove'sto normal f6ng6, ABS inhibition is canceled.19.73
rimln CpU anO suU CeU ch€ck each other undercertain condnions. Whon rhe CPUS dstectthe fol'lowing discrepanaies, rhe ABS indicator light comss on. whe; rh€re is discGpancv n lhacarculated wheelspeed velocirv thar continuosJor more than a given
.i^/hen rhere is discrcoancv in the ehase informalion lhat continuesfor morerhan a given period' When rhere is discrepancY in thecalculared conlfol pa.amerer'. When thewatch dog conrrolp!lsetailslof a given penod. When th6 checkotth€ ROM tai1s.. when there is disrepancy inrhe data roading.nd wriung prcledurc ot RAM
19 7'l
tr
19-59

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

ABS Control Unit
Pulsers/Wheel
Sensors
Replacement
1. Remove the right side kick panel.
2. Disconnect the ABS control unit connecrors.
3. Remove the ABS control unit,
4. lnstall the ABS control unit in the reverse order of
removal,
CONNECTORS
19-76
Inspection
Check the front and rear pulser for chipped or dam-aged teeth.
Measure the air gap between the wheel sensor andpulser all the way around while rotating the pulser.
Slandard: 0.4 - 1.0 mm (0.02 - 0.04 in,
NOTE; lf the gap exceeds 1.0 mm (0.04 in), theprobability is a distorted suspension arm which
should be replaced.
Dbc brake typo
0.{ - 1.0 mm(0.02 - 0.04 in)
Drum brake typ6
1.

l}tWheel Sensor Replacement
NOTE:
. Becareful when installingthe sensors to avoid twisting the wires.
. The torque value of the bolts is 9.8 N.m (1.0 kgf.m, 7 lbf.ft).
Front
FRONT WHEEL SENSOR
Rear
1. Remove the hub bearing unit (see section 18).
2. Remove the four backing plate bolts.
3, Pull the backing plate away from the trailing arm, then remove the wheel sensor. lt is not necessary to disconnect the
brake line.
NOTE: This illustration is drum brake type. The torque value of the disk type is same as drum type.
REAR WHEEL SENSOR
J\
It
19-77

Overhaul
1.
3.
Pull out the A,/C thermostat sensor from the evapo-
rator fins.
Remove the self-tapping screws and clamps from
the housings.
Carefully separate the housings, then remove the
evaporator.
lf necessary, remove the expansion valve.
NOTE: When loosening the expansion valve nuts, use
a second wrench to hold the expansion valve or the
evaporator pipe. Otherwise, they can be damaged
5. Assemble in the reverse order of disassembly Make
note of following items.
. Replace the O-rings with new ones at each fitting,
and apply a thin coat of refrigerant oil before
installing them.
NOTE: Be sure to use the right O-rings for HFC-
134a (R-134a) to avoid leakage.
. Install the expansion valve capillary tube so that
it is in direct contact with the suction line. Then
wrap wath taPe.
. Reinstall the Ay'C thermostat sensor to its original
location.
6th tin lrom inld side
Serpentine type:
Laminate typo:
TAPEReplace.lvake sure there is no foreign matter stuck between
60t5mml'2.1! O.2 inl
EVAPORATORblow din out of linswith compressed air,
HOUSING
8 N.m 10.8 kgt m,6 tbf.ftl
6th fin lrom outle't sideCAPILLARY TUAE
VALVEN
u'
ll
6\N.m (2.it kgt.m,17 tbtftl1l
A/C THERMOSTfesr page 22 21
%
EVAPORA
LOWER
22-29