13. Remove the upper radiator hose, heater hose and
water bypass hose.
WATER BYPASS
UPPEBRADIATORHOSE
17
HEATERHOSE
Remove the engine wire harness connectors and
wire harness clamps from the cylinder head and the
intake manifold.
o Four fuel injector connectors
. Engine coolant temperature (ECT) sensor con-
neclor
. Radiator fan switch connector
. Coolant temperature gauge sendlng unlt connec-
tor
. Throttle position sensor connector
. Manifold absolute pressure {MAP) sensor con-
nector
Primary heated oxygen sensor (primary HO2S)
connector
ldle air control (lAC) valve connector
Distributor connector
Remove the spark plug caps and distributor from the
cylinder head.
Remove the cruise control actuator (see section 4).
Support the engine with a jack, then remove the
upper bracket. Make sure to place a cushion
between the oil pan and the iack (see page 6-10).
a
18. Remove the cylinder head cover.
19. Inspect the timing belt (see page 6-9).
CYLINDER
(cont'd)
6-19
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Component Locations
lndex
'97 - 98 models:
MANIFOLD ABSOLUTEPRESSURE IMAP} SENSORTroubleshooting, Page 1 1-90
THROTTLE POSITION (TP}
SENSORTroubleshooting, page 1 1-103
toLE AtR CONTROL llAcl VAI-VE
Troubleshooting, page 1 1-152
EVAPORATIVE EMISSION (EVAP)
CONTROL CANISTER VENT SHUTVALVE t'98 mod€llTroubleshooting, page 11'213
INTAKE AIR TEMPERATUREIIATI SENSORTroubleshooting. page 1 'l -95
ELECTRICAL LOADDETECTOR IELD) (USA modol)Troubleshooting, page 1 1-138
VEHICLE SPEEDSENSOR (VSS)
Troubleshooting,page 11'135
CRANKSHAFTPOSTTtON/
POWER STEERING PRESSURElPsPl swtrcHTroubloshooting, page 1 1-162
TOP OEAD CENTER/CYLINDERPOStTtON{CKP/TDC/CYP} SENSOR(Built into the distributor)Troubleshooting, page 1 l-131
CMNKSHAFT SPEEDFLUCTUATION ICKF} SENSORTroubleshooting. page 1'!-142
ENGINE COOLANTTEMPERATUREIECTI SENSORTroubleshooting, page 11 99
EVAPORATIVEI€VAP) PURGE CONTROLSOLENOID VALVETroubf eshooting, page 1 1'2o5, 213
(cont'd)
11-3
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Component Locations
Index (cont'dl
39 - 00 models:
MANIFOLD ABSOLUTEPRESSURE IMAPISENSORTroubleshooting, page 1 1-90
THROTTLE POSITION {TP)SENSORTroubleshooting, page 1 1-103
IDLE AIR CONTROL OACI VALVETroubleshooting, page 1 1-152
EVAPOBATIVE EMISSION {EVAPICONTROL CANISTER VENT SHUTVALVETroubleshooting, page 1 1-213
EVAPORATIVE EMISSION(EVAPI PURGE CONTROI-SOLENOID VALVETroubleshootang, page 1 1-2'13
ELECTRICAL LOAOOETECTOR {ELD) IUSA modet)Troubleshooting, page I 1-138
INTAKE AIR TEMPERATURE(IAT) SENSORTroubleshooting, page 11 95
POWEB STEERING PRESSUREtPsPt swtTcHTroubleshooting, page 11 162VEHICLE SPEEDSENSOR IVSSITroubleshooting,page 11'135
CRANKSHAFTPOSTTTON/TOP OEAD CENTER/CYLINDERPOStTtON{CKP/TDC/CYP) SENSOR(Built into the distributor)Troubleshooting, page 11 131
CRANKSHAFT SPEEDFLUCTUATION ICKN SENSORTroubleshooting, page 1 1-142
SENSORTroubleshooting, page '11 130
ENGINE COOLANTTEMPERATURE{ECT)SENSORTroubleshooting, page 11 99
11-4
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System Description
Vacuum Connections (cont'dl
'97 model:
ENGINECOOLANT
ITr|ll
O PRIMARY HEATED oxYGEN sENsoR {PRIMARY Ho2s,SENSOR lt
O SECONDARY HEATED oxYGEN sENsoR {SECoNDARYHO2S. SENSOR 2l€) MANIFOLD ABSOLUTE PRESSURE (MAPI SENSOR@ ENGINE cooLANT TEMPERATURE {EcT} sENsoRO INTAKE AIR TEMPERATURE (IAI} sENsoR@ CRANKSHAFT SPEED FLUCTUATION ICKFI SENSORO |DLE ArR coNTRoL {tAc)vALvE@ FAST IDLE THERMo vALvEO THRoTTLE EoDY ITB)@ FUEL INJEcTonO FUEL PULSATIoN oAMPER@ FUEL FILTEn(} FUEL PRESSURE REGULATOR
FUEL PUMPFUEL TANKFUEL TANK EVAPORATIVE EMISSION (EVAPIVALVEAIR CLEANERRESONATORPOSITIVE CRANKCASE VENTILATION {PCVI VALVEEVAPORATIVE EMISSION {EVAP} PURGE CONTROLSOI.'ENOID VALVEEVAPORATIVE EMISSION {EVAP) CONTROL CANISTEREVAPORATIVE EMISSION {EVAPI TWO WAY VALVETHREE WAY CATALYTIC CONVERTER (TWC)
@(D(D
o@(}
@
@@@
1 1-10
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System Description
Vacuum Connections (cont'dl
'99 - q) models:
ENGINECOOLANT
t
o
o
o@
o@@@@@@@@@(t
PRIMARY HEATED OXYGEN SENSOR IPRIMARY HO2S,SENSOR 1lSECONDARY HEATED OXYGEN SENSOR {SECONDARYHO2S. SENSOR 2lMANIFOLD ABSOLUTE PRESSURE (MAPI SENSORENGINE COOLANT TEMPERATURE IECN SENSORINTAKE AIR TEMPERATURE IIATI SENSORCRANKSHAFT SPEED FLUCTUATION {CKF) SENSORKNOCK SENSOR (KS}
IDLE AIR CONTROL IIACI VALVEFAST IDLE THERMO VALVE {A/T}THROTTLE BODY (TB}
FUEL INJECTORFUEL PULSATION DAMPERFUEL FILTERFUEL PRESSURE REGULATORFUEL PUMPFUEL TANKFUEL TANK EVAPORATIVE EMISSION (EVAPI VALVE
AIR CLEANERRESONATORPOSITIVE CRANKCASE VENTILATION (PCV} VALVETHREE WAY CATALYTIC CONVERTER ITWCIEVAPORATIVE EMISSION {EVAPI CONTROL CANISTEREVAPORATIVE EMISSION IEVAPI PURGE CONTROLSOLENOID VALVEEVAPORATIVE EMISSION {EVAPI CONTROL CANISTEFVENT SHUT VALVEEVAPORATIVE EMISSION IEVAPI TWO WAY VALVEEVAPONANVE EMISSION {EVAPI AYPASS SOLENOIDVALVEFUEL TANK PRESSURE SENSOBEVAPORATIVE EMISSION IEVAPI THREE WAY VALVEPURGE JOINT
@@@@@@
@
@@
@@@
11-14
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ECM/PCM Data
By connecting the OBD ll scan tool or the Honda PGM Tester to the 16P data link connector (OLC), various data can be
retrieved from the ECM/PCM. The items listed in the table below conform to the SAE recommended practice
The Honda PGM Tester also reads data beyond that recommended by SAE.
understanding this data will help to find the causes of intermittent failures or engine problems.
NOTE:
The ',operating values" given below are approximate values and may be different depending on the environment and
the individual vehicle.
Unless noted otherwise. "at idle speed" means idling with the engine completely warmed up, transmission in position
Park or neutral and the A,./C and all accessories turned otf.
DataDesc.iptionOp€rating ValuoFreeze Data
Diagnostic
Trouble Code
(DTC)
lf the ECM/PCM detects a problem, it will store it as a
code consisting of one letter and tour numbers
Depending on the problem, an SAE-defined code (Poxxx)
or a Honda-defined code (P'lxxx) will be output to the
tester.
lf no problem is detected,
there is no output.
YES
Engine SpeedThe ECN4/PCN4 computes engine speed from the signals
sent from the Crankshaft Position sensor.
This data is used for determining the time and amount of
fuel iniection.
Nearly the same as
tachometer indication
At idle speed:'97 - 98 models:
750 t 50 rpm'99 - 00 models:
730 f 50 rpm
YES
Vehicle SpeedThe ECM/PCM converts pulse signals from the Vehicle
Speed Sensor (VSSI into speed data.
Nearly the same as
speedometer indicationYES
Manifold
Absolute
Pressure (MAP)
The absolute pressure caused in the intake manifold by
engine load and speed.
With engin6 stopped:
Nearly the same as atmo-
spheric pressure
At idle speed:
2a - 41 kPa {210 - 310
mmHg, 8.3 - 12.2 inHg)
YES
Engine Coolant
Temperature
{ECT)
The ECT sensor converts coolant temperature into volt-
age and signals the ECM/PCM. The sensor is a thermistor
whose internal resistance changes with coolant tempera-
ture. The ECM/PCM uses the voltage signals from the
ECT sensor to determine the amount of injected fuel
With cold engine:
Same as ambient temPer-
ature and IAT
With engine warmed uP:
approx. 163 - 2'12'F
(73 - 100"c)
YES
Heated Oxygen
Sensor (HO25)
(Primary,
Sensor 1)
(Secondary
Sensor 2)
The Heated Oxygen Sensor detects the oxygen content in
the exhaust gas and sends voltage signals to the
ECMiPCM. Based on these signals, the ECM/PCM controls
the airlfuel ratio. When the oxygen content is high (that is.
when the ratio is leaner than the stoichiometric ratio), the
voltage signal is lower.
When the orygen content is low (that is, when the ratio
is richer than the stoichiometric ratio), the voltage signal
is higher.
0.0 - 1.25 V
At idle speed:
about 0.1 - 0.9
NO
(cont'd)
1 1-65
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Troubleshooting
Troubleshooting Procedures (cont'd)
DataDescliptionOperating ValueFreezo Data
HO2S
Feedback
Loop Status
Loop status is indicated as "open" or "closed".
Closed: Based on the HO2S output, the ECM/pCM deter-mines the airlfuel ratio and controls the amount ofinjected fuel.
Open: ignoring HO2S output, the ECM/pCiM refers to sig,nals from the TP, MAP, and ECT sensors to control theamount of injected fuel.
At idle speed: closed
YES
Short Term
Fuel Trim
The airlfuel ratio correction coefficient for correcting theamount of injected fuel when HO2S feedback is in theclosed loop status. When the signal from the HO2S isweak, short term fuel trim gets higher, and the ECM/PCMincreases the amount of injected fuel. The airlfuel ratiogradually gets richer, causing a higher HO2S output.Consequently. the short term fuel trim is lowered. andthe ECM/PCM reduces the amount of injected fuel.This cycle keeps the airfuel ratio close to the stoichio-metric ratio when in closed looD status.
t:20y"
YES
Long Term
Fuel Trim
Long term fuel trim is computed from shon term fueltrim and indicates changes occuring in the fuel supplysystem over a long period.
lf long term fuel trim is higher than 1,00. the amount ofinjected fuel must be increased. lf it is lower than L00.the amount of injected fuel must be reduced.
! 20%
Intake Air
Temperature
(IAT)
The IAT sensor converts intake air temperature into volt-age and signals the ECrU/PCM. When intake air tempera-ture is low, the internal resistance of the sensorincreases, and the voltage signal is higher.
With cold engine:
Same as ambient temper-
ature and ECTYES
Throttle
Position
Based on the accelerator pedal position, the openingangle of the throttle valve is indicateo.At idle speed:
approx. 10%
lgnition
Timing
lgnition timing is the ignition advance angle set by theECM/PCM. The ECM/PCM matches ignition timing to thedriving conditions.
At idle speed: 16'1 4.
BTDC with the SCS ser-
vtce connector connected.
NO
Calculated
Load Value(cLV)
CLV is the engine load calculated from the MAp data.At idle speed:
2A - 410/o
At 2,500 rpm with no load:
13 - 260/o
YES
_
1 1_66
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Troubleshooting
Powertrain Gontrol Module Terminal Arrangement -'97 Model (cont'd)
PCM CONNECTOR O {16PI
PCM CONNECTOR D (I6P)Wire side of f6male terminals
NOTE: Standard battery voltage is 12 V.
f.rminal
numbcrWir! colorT€rminal nam6DescriptionSignal
1RED/BLKTPS ffHROTTLE
POSITION SENSOR}
Detects TP sensor signal.With throttle fullv oDen: about 4.8 V
With throttle fullv closed: about 0.5 V
RE D,4/VHT
ECT (ENGINE COOLANT
TEMPERATURE
SENSOR
Detects ECT sensor signal.With ignition switch ON {ll): about
0.1 - 4.8 V (depending on engine
coolant temperature)
RED/GRN
MAP (MANIFOLD
ABSOLUTE PRESSURE
SENSOR)
Detects MAP sensor signal.With ignition switch ON (ll): about 3 V
At idle; about 1.0 V(depending on engine speed)
YEUREDVCCl (SENSOR
VOLTAGE)
Pow€r source for MAP sensor.With ignition switch ON (ll): about 5 V
With ignition switch OFF: 0 V
EG R N/WHT
BKSW (BRAKE
SWITCH)
Detects brake switch signal.With brake pedal released:0 V
With brake pedal depressed: battery
voltage
7WHT
PHO2S (PRIMARY
HEATED OXYGEN
SENSOR SENSOR 1)
Detects heated primary oxygen
sensor (sensor 1) signal.
With throttle fully opened from idle with
fully warmed up engine: above 0.6 V
With throttle quickly closed: below
0.4 v
8RED//E L
IAT (INTAKE AIR TEM.
PERATURE SENSOR)
Detects IAT sensor signal.With ignition switch ON lll): about
0.1 - 4.8 V (depending on intake air
temperaturel
10YEUBLUVCC2 (SENSOR VOLT-
AGEI
Provides sensor voltage.With ignition switch ON (ll): about 5 V
With ignition switch OFF: 0 V
11GRN/BLKSG2 (SENSOR
GROUND)
Sensor ground.Less than 1.0 V at all times
12GRN/WHTSGl (SENSOR
GROUND)
Ground for MAP sensor.Less than 1.0 V at all times
13RED/YE L
SHO2S SG(SECONDARY HEATED
OXYGEN SENSOR,
SENSOR 2 GROUND)
Ground for secondary heated
orygen sensor (sensor 2).
14WHT/RED
SHO2S (SECONDARY
HEATED OXYGEN
SENSOR, SENSOR 2)
Detects secondary heated
orygen sensor (sensor 2)
signal,
With throttle fully opened from idle with
fully warmed up engine; above 0.6 V
With throttle quickly closed: below
0.4 v
16*GRN/RED
EL (ELD)Detects ELD signal.With parking lights turned on at idle
about 2.5 - 3.5 V
With low beam headlights turned on
at idle: about 1.5 - 2.5V
1-70
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