start circuit HONDA CIVIC 1997 6.G Workshop Manual
[x] Cancel search | Manufacturer: HONDA, Model Year: 1997, Model line: CIVIC, Model: HONDA CIVIC 1997 6.GPages: 2189, PDF Size: 69.39 MB
Page 161 of 2189
VTEC Control SYstem
The scan tool indicates Diagnostic Trouble Code {DTC) Pl259:
VTEC Solenoid Valve circuit
Refer to page 1'l-38 through 11 55 before troubleshooting
Troubleshooting Flowchart
YES
A problem in the WEC Pressure Switch circuit or
* Road Test:Accelerate in 1st gear to an engine speed over 6,000 rp '
Hold that engine speed for at leasttwo seconos'
lf the DTC P1259 is not repeated during the first road test'
repeat this test two more times
VTEC PRESSURE SWITCH 2P
CONNECTOR
Terminalside ofmale termtnals
WM
/1 IBLU/BLKI
/ 1 Y------rt--------- l I
\1-/ |I
I
I1
Wire side of femaleterminals
(cont'd)
6-51
The MIL has been teported on.
DTC P1259 is siored.
Check the VTEC Control SYsiem:
1. Do the engine control module(ECM ) Reset Procedure (see
section 11).
2. Start the engine
3. Warm uP the engine to normal
operating temPerature (cool
ing fan comes on).
4. Do the Road Test.*lntermittent failure, sYstem is OK
at this time.Check for Poor connectlons or
loose wires at VTEC Pressureswilch. VTEC aolenoid valvo and
ECM.
ls DTC P1259 indicated?
Test the VTEC Pressure Switch:
1. Turn the ignition switch OFF.
2. Disconnect the VTEC Pressure
switch 2P connector.
3. Check for continuity between
VTEC pressure switch 2P con
nector telminal No 1 and
No.2.
Reolace the VTEC Pre3sure switch.
Test the VTEC Pressure Switch
Wire:1. Turn the ignition switch ON (ll).
2. N4easure the voltage between
VTEC press u re switch 2P
connector No. 1 and bodyground,
Inspect lor an open or short toground in the wire between the
VTEC orassure swilch and ECM
{c101.lf the wire i3 OK, substitute a
known-good ECM and recheck.
{To page 6 52)
Page 270 of 2189
!
Fuel and Emrsslons
SoecialToofs .....,...."..,. 11-2
Component Locations
lndex ....................., ......... 11-3
Svstem Description
Vacuum Connections ................,,..,.. ......... 11-12
Electrical Connections ...............,.,.,... ....... 11-29
System Connectors ........,.,.,.......................... 1 1-51
Troubleshooting
Troubleshooting Procedures ................. .. 11-81
Engine Control Module/PowertrainControl Module TerminalAfiangement ....,.,..... 11-88
Diagnostic Trouble Code Chart .................,., 11.97
How to Read Flowcharts .,.......................... . 11-103
PGM-Fl System
System Description ...... 11-10,1
Troubleshooting Flowcharts
Engine Control Module/PowertrainContlol Module ........ 11-107
Manitold Absolute Pressure Sensor .....'. . ... 11-115
fntake Air Temperatuie Sensor ..... . . ., . 11'121
Engine Coolant Temperatuae Sensol ........., 11-128
Throttle Position Sensor ...................,........... 11-132
Primary Heated Orygen Sensor (Sensor 1l ... 11-139
Secondary Heated Oxygen Sensor(Sensor 21.................................................... 1 1-153
Heated Oxygen Sensor Heater ...................,. 11-157
Fuel Supply System ...... 11-164
Random Mislire ......., ..11-166
Misfire Detected in One Cylindsr ................. 11-167
Knock Sensor .,.,............ 11-170
CKP/TDC/CYP Sensor ................................... 11'172
Vehicle Speed Sensor ...........,......,...,.,........... 1t-176
Barometric Pressure Sensor ...............,......... I 1-178
Electrical Load Detector,.,,............................ 1 1-179
CKF Sensor .................... 11-183
ECM/PCM Internal Circuit ............................. I 1-188
A/T Signal {TMA/TMBI .................................. I 1-189
ldle Control System
System Doscriplion ............ 11-190
Troubleshooting Flowcharts
ldle Control System ...... 11-192
ldle Air Control Va1ve .................................... I 1-19i1
Starter Switch Signal .................................... 1 1'202
Air Conditioning Signal ................................. 11'201
Ahernator FR Signal .................................... . 1 1-208
BrakeSwitch Signal ..................................... f 1"210
Power Sleering Prossure Switch Signal ......11-212
A/T Gear Position Signal ............................... 11-216
Clutch Swiich Signal ................................-.... 11-214
ldte Speed Setting . .............11-220
Fuel Supply System
Fuel Lines .,...................,.,.,.,11-221
Fuef Tube/Ouick-Connect Fittings ..........,.,........ 11 -227
System Description ....'.... 11-230
Fuel Pressure .......,.,,........... 11-230
Fuef fniectors ......................11-232
Fu€f Pressure Regulator .....,.......................'...,. 11-231
Fuef Fifter ............................11-235
Fuel Pump .............'.......'.... 11-236
PGM-FI Main Relay .............11'237
Fuel Tank ................ ....,...'.'.' 11'211
Intake Air System
System Description ....-.-.....11-243
Air Cfeaner ...........,......."". .11-211
Throttle Cable .....................11-211
Throttfe Body ........ ..'... . . .,.11-211
Fuel Iniestion Air Control System ,.,.,....-........... 11-250
Emission Control System
System Description .-..........11-252
Taifpip€ Emission ...............11-252
Three Way Catafytic Convert€r ............,.,,.,.,.,.... 11 -252
Exhaust Gas Racirculaiion System ...,.,,,,.,.,.,.,,. 11'254
Positive Crankcas€ Ventilation System .... . . .. 11-266
Evaoorative Emission Controls ..................,,..,.,. 11 -267
Page 359 of 2189
Troubleshooting
Engine/P_o_wgrtrain Control Module Terminal Arrangement('96 - 98 Models '99 - 00 Dt6y5 engine with M/T) tc'oniOi
ECM/PCM CONNECTOR C {31PI
1
CKFP
2
CXPPTDCPa
ACS
5
sTs
7
scsII
rMA
10
v8u121314t51517
ALTF
TE
vss23lP+
21252930
TMA
Wire side of female terminalsECM/PCM CONNECTOR C (31PI
NOTE: Standard baftery voltage is 12 V
'1: USA modelr2rA,.T (D16Y7, O16Y8 ensane)*3: CVT (O16Y5 engine)*4: Ay'T and O16Y7 engine'5: Excepl A./T snd Dl6Y7 engine16: Ay'T (D16Y8 ensine){7: CVT (Dl6Y5 eosine) and O16Y8 enoine"8: 96 Dl6Y8 engine (coupe),'97 D16y8 engine (coupe: atl:ed-9I t!!rnodelr,'98 D16y5 ensine,,98 D16y8 e;sine.D16Y5 lM/T) ensine
1-90
19: D16Y5 engine'10: M/T (Dl6Y5 engine)*11r Except M/T 116Y5 engine)*12: D16Y5, D16Y8 engine*13: Dl6Y8 enqine*14: O16Y7 enginei15: '-97 O16Y7 engjne (coupe: KL modet, sedan: KL (LX) modet),'98D16Y7 enqine'99 - 00
1
To.min!lnumberWiracoloaTorminalnameDo6criptlonSignal
1BLU/REDCKFP (CKF SENSOR P SIDE)Detects CKF sensor.With engine running: pulses2BLUCKPP (CKP SENSOF PSIDE)Detects CKP sensor.With engine running: pulses3GRNTDCP {TDC SENSOR PSIDE}Detects TDC sensor,With engine running: putses4YELCYPP (CYP SENSOR P SIDE)Detects CYP sensor.With engine running: pulses
5BLU/FEDACS {Tr'C SWITCH SIGNAL)Detects ,ay'C sw;tch signat.With Iy'C switch ONr 0 VWith Ay'C switch OFF: batrery vottage
6BLU/ORNSTS (STARTER SWITCHSIGNAL)Detects staner swilch signal,With staner switch ON ltlt): batery vohageWith staner switch OFF: 0 V
8RNSCS (SERVICE CHECKSIGNAL)Detects service check connector signal{the signalcausing a OTC indicationlWith the connector connected: O Vwith the connector disconnected: about 5 vor battery voltageLT 8LUK,LINE (DLC)Sends and receives scan iool signal,Wirh ignition switch ON { ): about 5 V
9+3GRYDat6 communication with TCM: ECMcontrol ctat6 outputWith ignition switch ON (tt):putses
10WHT/BLUVBU (VOLTAGE BACK UP)Power source forthe ECM/PCMcontrol circuit. Power sourc€ lortheDTC memory
Battery voltage at all times
11WHT/REDCKFM {CKF SENSOR MSIDE)Ground tor CKF sensor signal.
12CKPM (CKP SENSOR MSIDE)Ground for CKP sensor s;gnat.
REDTDCI\4 (TDC SENSOR MSIDE)Ground for TDC sensor signal.
14BLKCYPM (CKP SENSOB MSIDE}Groond for CYP sensor signal.
15."BLU/BLKVTM (VTEC PRESSUREswtTcH)Oetscts VTEC pressure switch signal.Wrth engine at low enginespeed:0 VWth engineathigh engine speed: tatteryvoltase
16GRN
PSPSW (P/S OIL PRESSUREswtTcH)Detects PSP switch signal.At idle with steering wheel in straight aheadposition:0 VAt idle with stsering wheet at fult tock batteryvoltage'17WHT/REDALTF (ALTERNATOR FRSIGNAL)Detects ahernator FR signal.With fullyw6rmed up engine running:0 V- bat-teryvohage (depending on electricat toad)18BLUI/VHTVSS {VEHICLE SPEED SEN-SOR}Oetects VSS signal.Whh ignitjon switch ON {tt) and front wheetsrotating: cycles 0 V- 5 V23+14BLKlP+ {HO2S PUtr4P CELL +}Controls HO2S pump ce .With ignition switch ON (ll): abour 0.5 - 5.3 V
24.10REDrP-, vs- {Ho2s coMt oN)Reference voltage supply.With fullywarmed up engine et idle:about2.6-2.8 V25*roVS+ (VS CELL VOLTAGE)Detects VS cell voltage.With ignition switch ON t): abour 7 V
29LT GRN*'ATPNP (Ar'T GEAR POSI,TroN swrTcH)Deteds Ay'T g6srposhion switch signat.In E orE position: O Vln any other position: battery vottage
RED{roCLSW (CLUTCH SWITCH}Detects clutch switch signal,Wilh clutch pedal released: about 5 VWith clutch pedal deDressed: O V30PNK4TMBData communication with TCM:ECM controldata inputWith ignit;on switch ON (lt):putses
Page 362 of 2189
ECM/PCM CONNECTOR B (25PI
Wire side of female terminals
FCM CONNECTOR B {25P)NOTE: Standard battery voltage is 12 V
Sign.l
YELtsLKIGP1 IPOWER SOUflCE)Powor sou rca for the ECM/PCM conlrolcirwhh ignilion swilch ON (ll)ibatteryvoltageWith ignition switch OFF:0 V
BLKPGl {POWEB GNOUND)Ground fo. the ECM,/PCM contrclcncuit'Less than 1.0 V at slltimes
FEDlNJ2 (No 2 FUEL INJECIOR)Drives No. 2 fu€l inieclor'Wirh enqine runnin9: dulv conlroll6d
BLUlNJ3 (No.3 FUEL INJECTOB)Orives No.3 fuel inieclor'
YELlNJ,r lNo. 4 FUEL INJECTOF)Drives No. 4 luel injector'
6BLI(BIUIACV P (IDLE AIR CONTROLVAIVE POSITIVE SIDE)O.iv€s IAC valve {Posirivo side)Wilh engine running: duty conrrollod
BEDESOL {EG8 CONTROLSOLENOID VALVE)Drives EGF controlsolonoid valveWith EGR operaiing during driving wirh follv warmedup onginsl dutY controlledWilh EGR nol op€r.ring:0 V
PNKSLKHlC tstvr (PH-PL CONTnOLLINEAfl SOLENOID NEGATIVEst0E)
G rcund for PH-PL control linsar solsnoid
8.,LS - (A/T CLUTCH PFESSURECONTROL SOTENOIDVALVE'sroE)
A/Tclutch prsssure conrrol sol€nod valv€pow6r slpply negative elecrodeWith ignilion swirch ON (ll):dutv controll€d
9YEUBLKrGP2 {POWE8 SOUFCE)Powor $urce for lhe ECI{,'PCM controlc'rcuitwnh ignirion swirch ON (ll): ban€ry voltag€with ignirion swnch oFF:0 v
10BLKPG2IPOWER GSOUNDIGround lor ths ECM/PCM controlctrcuil
118RNINJl {No,1 FUEL INJEqIOR)orives No. r ru6l Iniocror.With onsino at low lpm:0Vwith ens,n. ar hish tpm:bsneryl9!9gl-12"GRN,.YELWS (WEC SOLENOID VALVE)Orivos WEC solanoid v.lvs.
13YEUGRNICM {I6NITION CONTROL MODULE}
With ignition switch ON (ll)r b5n6ry volt€gsWilh engino running: Puls6
15ORNIACV N (IDLE AIN CONTSOIVALVE NEGATIVE SIOE)Drivos the IAC valve lnogativ€ 3idelWith €ngin€ ru nningi dr]tv controlled
REDLS + (A,/T CIUICH PRESSURECONTFOT SOIENOIOVALVE +SIDE}
A/T clutch pr€so.6 controlsolenoid valvepow6r slpply posiliv€ oroclrodeWirh ignition swatch ON (lll: dutYcontrorled
HLC LSP (PH-PI CONTROI LIN.EA8 SOLENOID POSITIVE SIDE)Orives PH-PL control line€r solenoidWith qnition switch ON (lll: Pulsing srgnal
PNK/BTUSC LSM (STAfiT CLUTCHLINEAR SOLENOIO N€GATIVESIDE)
Groundforstartclutchcontrol line6r
20BnN/AtKLGI (LOGIC GEOUNO)Ground for lh€ EcM/PcM controlcircuit'L6se rhan 1.0 v.i alltimes
21VBU IVOLTAGE 8AC( UP)Powet source torlhe ECM/PCM control circuitPower sourco tor th6 DTC m€mory'Battaryvoltage aitnEtrmes
22BFN/8IKLG2 (LOGIC GSOUND)Ground iorths ECMnCM conrrol circuir'tsss thah 1.0 v al all times
238LI(BLUIACV (IOTE AIR CONTROLWitn ongine funning: dutv conrol!6d
25'3YELSC LSP {STANT CLUTCH LINEARsotENorD PoSlrlvE slDE)Orives sran clutch control linesr solonoid.With ignilion swilch ON (ll): Pulsing sign3r
r1: A/r (D16 , D16Y8 ensins)
'3:CVT {O16Y5ensino)
'4: Ol6Y5, Dl6Y8, B164? onsina
(cont'd)
1 1-93
Page 372 of 2189
How to Read Flowcharts
A flowchart is designed to be used from start to final repair. lt's like a map showing you the shortest distance. But beware:
lf you go off the "map" anywhere but a "stop" symbol, you can easily get lost.
tSrARTl(bold type)
FanoNl
@
tsroP I
{bold type)
Describes the conditions or situation to start a troubleshooting flowchart.
Asks you to do something; perform a test, set up a condition etc.
Asks you about the result of an action, then sends you in the appropriate troubleshooting direction.
The end of a series of actions and decisions. describes a final repair action and sometimes directs you to
an earlier part of the flowchart to confirm your repair,
NOTE:
. The term "lntermittent Failure" is used in these charts, lt simply means a system may have had a failure. but it checks
out OK at this time. lf the Malfunction Indicator Lamp (MlL) on the dash does not come on, check for poor connections
or loose wires at all connectors related to the circuit that you are troubleshooting (see illustration below)'
. Most of the troubleshooting flowcharts have you reset the Engine Control Moduls (ECM)/Powertrain Control Module
(pCM) and try to duplicate the Diagnostic Trouble Code (DTC). lf the problem is intermittent and you can't duplicate the
code, do not continue though the flowchart. To do so will only result in confusion and, possibly, a needlessly replaced
ECM/PCM.
. ,,Open" and "Short" are common electrical terms. An open is a break in a wire or at a connection. A short is an acci-
dental connection of a wire to ground or to another wire. In simple electronics, this usually means something won't
work at all. In complex electronics (like ECM's/PCM'sl. this can sometim€s mean something works, but not the way it's
suDDosed to.
toosE
1 1-103
Page 374 of 2189
3.
5.
6.
1.
Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at
speeds over the following rpm:. D16Y5 engine (M/T):850 rpm. D]6Y5 engine (CVT), D'16Y8 engine (USA M/T): 920 rpm
. Dl6Y8 engine (USA A,/I), D16Y7 engine (USA A,/T);910 rpm
. D16Y8 engine (Canada M/T), D16Y7 engine (canada): 990 rpm
' D16Y8 engine (Canada M/T): 1,000 rpm
. 816A2 engine: 970 rpm
. Fuel cut-off action also takes place when engine speed exceeds 6,900 rpm (D16Y5, D16Y7 engine; D'16Y8 engine:
7,000 rpm. 816A2 engine: 8.100 rpm), regardless of the position of the throttle valve, to protect the engine from
over-rewing. With '99 Dl6Y7 engine (A,/T) and '99 D16Y8 engine (A./T), the PCM cuts the fuel at engine speeds over
5,000 rpm when the vehicle is not moving.
IVC Compressor Clutch Relay
When the ECM/PCM receives a demand for cooling from the air conditioning system, it delays the compressor from
being energized, and enriches the mixture to assure smooth transition to the A,/C mode
Evaporative Emission (EVAP) Purge Control Solenoid Valve*'
When the engine coolant temperature is above 154'F (68'C). the ECM/PCM controls the EVAP purge control solenoid
valve which controls vacuum to the EVAP purge control canister.
Evaporative Emission (EVAP) Purge Control Solenoid Valve*a
When the engine coolant temperature above 154"F (68"C), intake air temperature above 32"F (0'C) and vehicle speed
above 0 mile (0 km/h) or [Ay'C compressor clutch on and intake air temperature above 160"F (41'C)], the ECM/PCM
controls the EVAP purge control solenoid valve which controls vacuum to the EVAP purge control canister.
Exhaust Gas Recirculation (EGR) Control Solenoid Valve*?
When EGR is required for control of oxides of nitrogen (NOx) emissions. the ECM controls the EGR control solenoid
valve which supplies regulated vacuum to the EGR valve
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode,
which reduces the engine load to improve the fuel economy.
ECM/PCM Fail-safe/Back-up Functions
1. Fail safe Function
When an abnormality occurs in a signal from a sensor, the ECM/PCM ignores that signal and assumes a pre-pro-
grammed value for that sensor that allows the engine to continue to run.
2. Back-uD Function
When an abnormality occurs in the ECM/PCM itself, the fuel injectors are controlled by a back-up circuit independent
of the system in order to permit minimal driving.
3. Self diagnosis Function lMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the lvllL and stores the DTC
in erasable memory. When the ignition is initially turned on, the ECM/PCM supplies ground for the MIL for two sec-
onds to check the MIL bulb condition.
4. Two Trip Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S, fuel metering-related. idle control
system, ECT sensor, EGR system and EVAP control system self-diagnostic functions. When an abnormality occurs,
the ECM/PCM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and
ON 0l) again, the ECM/PCM informs the driver by lighting the MlL. However, to ease troubleshooting, this function is
cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs,
5. Two (or Three) Driving Cycle Detection Method
A "Driving Cycle" consists ot starting the engine. beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions is detected during two consecutive driving cycles, or TWC deterioration is detected dur-
ing three consecutive driving cycles, the ECM/PCM turns the MIL on. However, to ease troubleshooting, this function
is cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs.
(cont'd)
1 1-1 05
.1.
Page 397 of 2189
PGM-FI System
Engine Coolant Temperature (ECTI Sensor
The scan tool indicates Diagnostic Trouble code (DTC) P0116; A range/performance problem in the EngrneCoolant Temperature (ECT) Sensor circuit.
The ECT Sensor is a temperature dependant resistor (thermistor). The resistance of the thermistor decreases as the enginecoolant temperature increases as shown oetow.
RESISTANCE(ko)
NOTE: lf DTC P0117 and/or P01'18 are stored at the same time as DTCfor DTC P0116.
Possible Cause
. ECT sensor deterioration. Malfunction in the thermostat and cooling system
Troubleshooting Flowchart
-a 32 68 r0a la0l?6 2t2 2481'rr-20 o 20 ao o D r@ Il, r'c)
ENGINE COOLANT IEMPERATURE
P0116, troubleshoot those DTCS first. then recheck
11-128
THERMISTOR
- The MIL has bogn reported on.- DTC P0116 is stored.
Problem verification:1. Start the engine. Hotd theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check the
Intermiftent lailure. system is OKai thi. time. Ch.ck the thc.mo-stat 6nd thc cooling system.
is 176 200'F {80 - 93'C)or0.0-0.TVindicated?
Check the thermostat and thecooling system. ll they als OK,raplace the ECT sensor.
Page 406 of 2189
I
Throttle Position (TP) Sensor (' 99 - 00 Models except D16Y5 engine with M/Tl
The scan tool indicates Diagnostic Trouble Code {DTC) P0123: A high voltage problem in the Throftle Position
{TP) sensor circuit.
TP SENSOR 3P CONNECTOR {C11OI
sG2{GRN/BLKIvoc2
{YEUBLU}
'l'Wire side of female term;nals
ECM/PCM CONNECTOR C (31PI
Wire side of femal€ terminals
(cont'd)
11-137
The MIL has been reported on
DTC P0123 is slored.
Problem verification:1. Start the engine. Hold the
engine at 3,000 rpm with no
load (in Park or neutral) until
the radiator fan comes on
then turn the ignition swatch
OFF,2. Turn the;gnition switch ON (ll).
3. Check the throttle Positionwith the scan tool.
lntormittenl tailure, 3ystom is OK
at this time. Check tor Poor con'
neqtions or loo3€ wires at C'110(TP sensorl tnd ECM/PCM.
ls there approx. 10% when the
throttle is fully closed and
approx. 90% when the throttleis fully opened?
Ch€ck for an open in the TP s6n-
soJ:1. Turn the ignition switch OFF.
2. Disconnect the TP sensor 3P
3. Turn the ignition switch ON (ll).
4. At the wire harness side, mea-
sure voltage between the TP
sensor 3P connector terminalsNo. 1 and No.3.
ls there approx. 5 V?
Check tor an open in the wire(SG2lino):
Measure voltage between ECM/
PCM connector C (31Pi terminals
C18 and C28.
Repair open in the wite betwe€nECM/PCM (Cl81and TP son.or.ls there approx. 5 V?
Substitute a known-good ECM/PCM and recheck. lf Pr$cribedvoltage is now aveilabl6. replacethe original ECM/PCM.
Page 408 of 2189
Primary Heated Oxygen Sensor {Primary HO2SI (Sensor 1)
t('96 - 98 Models except Dl6Y5 engine with M/Tl
The Heated Oxygen Sensor (HO2S) detects the oxygen content in the exhaust gas and signals the ECM/PCM. In operation,
the ECM/PCM receives the sjgnals from the sensor and varies the duration during which fuel is injected To stabilize the
sensor,s output, the sensor has an internal heater. The Primary HO2S (Sensor 1) is installed in the exhaust manifold.
HO2S:
VOLTAGE {VI
The scan tool indicates Diagnostic Trouble Code (DTC) P0131; A low voltage
Oxygen Sensor (H02S) (Sensor 1) circuit.
R|cH-AIR- - LEANFUELRANO
problem in the Primary Heated
SENSOR
ztRcoNlA
The MIL has be€n teported on.DTC P0131 is siorcd.
Problom verificalion:1. Do the ECM/PCM Reset Pro'
cedure.2. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on,3. Test-drive with the A/T in Eposition (M/T in 4th gear)
4. Check the Primary HO2S(Sensor 1) output voltage with
the scan tool during accelera-
tion using wide open throttle.
lntcrmift€nt failura, 3Y3tem is OKat this tims. Check for Poor con-nections or loo3e wi.o3 at C123(Primlry HO2S, 3sn3or 1) and
ECM/PCM,
(To page 1I-140)
{cont'd)
1 1-139
Page 410 of 2189
Primary Heated Oxygen Sensor (Primary- Fjq?S) (Sensor 1l
('99 - 0b Models exiept D16Y5 engine with M/T)
TheHeatedoxygensensors(Ho2S)detecttheoxygencontentintheexhaustgasandsigna|stheEcM/PcM'|noperation,
the EcM/pcM receives the signars from the sensor and varies the duration during which fuel is injected. To stabilize the
sensor,soutput,thesensornasaninternaIheater.ThePrimaryHo2S(sensorl)isinsta|ledinexhaustmanifo|d(D16Y8.
81642 engine: exhaust PiPe A)
SENSORTERMINALSVOLTAG€ (VI
HEATERTERMINALS
The scan tool indicates Diagnostic Trouble Code (DTC) P0131: A low voltage
Oxygen Sensor (HO2S) (Sensor 1) circuit
RICH+ AIR- - LEANFUELRATIO
problem in the Primary Heated
HEATER
- The MIL has been t€Ported on.- DTC P013'l is stored.
Problem veritication:1. Do the ECM/PCM Reset Pro-
2. Start the engine. Hold the
engine at 3,000 rpm wrth no
load (in Park or neutral) until
the radiator fan comes on
3. Check the PrimarY HO2S
lSensor 1) output voltage wath
the scan tool during accelera
tion using wide open throttle
lntermittont f.ilure, 3ystem i3 OK
at thi3 time. Check tor Poor con'
nections or loose wires el C123
{Primary HO2S, Sensor 1) and
ECM/PCM.
Does the voltage stay at 0 5 v
or less?
Check the fuel pressLlre (see Page11,109).
(To page 11 142)(cont'd)
11-141