Start HONDA CIVIC 1997 6.G Owner's Manual

EGT Switch
-f
Testing
Replace the thermostat if it is open at room temperature'
To test a closed thermostat:
1, Suspend the thermostat in a container of water as
shown.
THEBMOMETER
THERMOSTAT
Heat the water, and check the temperature with a
thermometer. Check the temperature at which the
thermostat first opens, and at which it is fully open
CAUTION: Do not let the thermometer touch the
bottom of the hot Gonlainel.
Measure lift height of the thermostat when fully
open.
STANDARD THERMOSTAT
Lift height above 8.0 mm (0.31 inl
Starts opsning: 169' - 176'F (76' - 80'Cl
Fully open: 194'F {90"C1
!'o
10-1 1
Testing
!!@ Romoving the EcT swhch while lhs engine
i!-ot can cause the coolant to sPray out, seriously scald-
ing you. Always lst th€ ongine and rediator cool down
before removing ihe ECT switch.
NOTE: Bleed air from the cooling system after installing
the ECT switch (see Page 10-7)
1. Remove the ECT switch from the thermostat hous-
ing (see Page'10-10).
2. Suspend the ECT switch in a container of water as
shown.
Heat the water, and check the temperature with a
thermometer.
CAUTION: Do not let the thermomoter touch tho
bottom of the hot container'
Measure the resistance between the A and B termi-
nals according to the table.4.
Terminal
Oo"rffi
swlTcH
ON196' - 203"F
(91" - 95'C)o--o
OFF
5" - 15'F {3" - 8'C)
lower than the temPera-
ture when t goes on

!
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

Electrical Connestions ('99 - 00 Models except Dl6Y5 engine with M/Tl
L ChUISE COXTnOI UNII
lo CO|IPi€33OR CUrrcH BEI Y
lo A/c PRESSUiE alYrc|l
To FAoIAIOR FAI REL Y EcT3wllcll
SENSOF
FIJSES:(D IN1ERIOR UGHT O5A) '
@ BACK UP O5A*@HonN (15A).(DSATTERY OOA*@ rcl (104*
@FrvM (r5A*
@No. I3FUELPLMP (lEA)
@ No. 25 MEIER CrsA)@ ib. 15 ALTERNATOR SP SEI{SOR OJA)
O ib. 3l STARTER SIGML (75A)': h lhc ud.rhood lu..//rcbY box(cont'd)
11-39
-:
T
)
I
FUEI II{JECIOBS

Troubleshooting
Troubleshooting Procedures (cont,dl
ll, Engine Control Module (ECM)/powertrain Control Module (pCM) Reset procedure
NoTE: Resetting the EcM/PcM will erase any stored DTcs and any freeze data. lt will also restart all readiness codemonitors.
Either of the following actions will reset the ECM/PCM.
. Use the OBD ll scan tool or Honda pGM Tester to clear the EClM,s/pCM,s memory.
NorE: see the oBD ll scan tool or Honda PGM Tester user's manuals for specific operating instructions.
' Turn the ignition switch oFF. Remove the BACK uP (7.5 A) fuse from the under-hood fuse/relay box for 10 sec-onds.
NorE: Bemoving the BACK uP (7 5 A) fuse cancels the clock and the radio presets. Make note of the customer,spresets so you can reset then
lll. Final Procedure (this procedure must be done after any troubleshoottng)
1. Remove the SCS Service Connector if it is connected.
NoTE: If the Scs service connector is connected and there are no DTcs stored in the EcMipcM, the MtL will stayon when the ignition switch is turned ON 0l).
2. Do the ECM/PCM Reset procedure.
3. Turn the ignition switch OFF.
1-82

Troubleshooting
Troubleshooting Procedures (cont,dl
CAUTION:
. Punqturing ihe insulation on a wirs can cause poor or intermiftent electricar connections.I Bring the test€r probe into contacl with the terminatlrom the terminal side of wire harnesg conncctors in the gngin€compartment. For temale connectors, iust touch lightly with the tester probe and do not inse.t the probe.
\I
RUBBER SEAL
Other Probable Causes for an engine that will not start:- Compression- Starting system- lntake air leakage - Overheating- Engine locked up - Battery- Timing belt
TESTER PROBE
Symptom Chart
Listed below are symptoms and probable causes for problems that Do NoT cause the Malfunction indicator Lamp (MlL) tocome on. lfthe MIL was reported on, go to page 11_81.Troubleshoot each probabre cause in the order risted (from reft to right) untir the symptom is eriminated.The probable cause and troubleshooting page reference can be found berow.
L
*: '99 - 00 models
TERMINAL
SYMPTOMPROBABLE CAUSE
4,2,3, 5,20, 14, 1
2, 4, 11, 16, 13, 't9
?, s^6. 16
1,8,10.9
Engine will not sta rt
Hard starting
Cold fast idle too low
Cold fast idle too high
ldle speed fluctuates7,8, 10.9
Troubleshoot for misfire on pages l1-166, 167Misfire or rough running
LOW power
E"g|* "t"lb
2,9, 10, 12, 11, 16, 't8,20
2,4,11,7,20,8,5,15
't9, 21
1r, ,1
Difficult to refuel*
Fuel overflows during refueling*
11-84

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

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

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

PGM-FI System
System Description
CKP/TDC/CYP Sensor
MAP Sensor
IAT SensorTP SensorEGR Valve Lift Sensor*'Primary H02SSecondary HO2SVSSBARO SensorELD*'KS€Starter SignalALT FR SignalAir Conditioning SignalA/T Gear Position SignalBattery Voltage {lGN.1}Erake Switch SignalPSP Switch SignalFuel Tank Pressure Sensor*iVTEC Pressure Switch*5Clutch Switch Signal*6Countershaft Speed SensornBMainshaft Speed Sensorrs
-\
----t /
F;ilrr j"-----fi-tri-'r.;l
Fb"t."'i" d" c;;il
F,h"'c;;tr*".io";-l
@."r.l"sc;;ll
EaM/PcM B""k-p F"""till
r\
-:/
Fuel IniectorsPGM-Fl Main Belay {Fuel Pump)MILIAC Valve!y'C Compressor Clutch RelayRadiator Fan Relay*,Condenser Fan RelayALT*'lcMEVAP Purge Control Solenoid
Primary HO2S HeaterSecondary H02S HeaterEGR Control Solenoid Valve*rEGR valve*6EVAP Bypass Solenoid Valve*'EVAP Control Canister Vent Shut
VTEC Solenoid Valve*5DLCLock-up Control Solenoid Valve*aShift Control Solenoid Valve*3Linear Solenoid Valve*3
*1: Dl6Y5 engine*2: USA model*3: CW (D16Y5 ensine), D16Y8 engine and 81642 ensine*4: '96 D16Y8 engine lcoupe),'97 Dl6Y7 engine (coupe: KL model, sedan: KL (LX) model),'97 D16Y8 engine {coupe: all models, sedan: KLmodel),'98-all models,'99'all models,'00-all models+5: D16Y5, D16Y8,816A2 engine*6: M/T (D16Y5 enginei*7: CVT 1D'l6Y5 engine)+8: A/T (D16Y7, D16Y8 engine)*9: '96 D16Y5 engine,'96 D16Y7 engine,'96 Dl6Y8 engine (sedan),'97 D16Y5 engine,'97 Dl6Y7 engine (coupe: KA, KC models, sedan:KA, KC, KL (LX) models, hatchback: all models),'97 D16Y8 engine (sedan: KA, KC modelsi
PGM-FI Sy3lem
The PGM-Fl system on this model is a sequential multipon fuel injection system.
Fuel iniector Timing and Duration
The ECM/PCM contains memories for the basic discharge durations at various engine speeds and manifold air flow rates.
The basic discharge duration, after being read out from the memory. is further modified by signals sent from various sen-
sors to obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve llAC Valve)
When the engine is cold. the A,/C compressor is on, the transmission is in gear, the brake pedal is depressed, the P/S load
is high, or the alternator is charging, the ECM/PCM controls current to the IAC Valve to maintain the correct idle speed.
lgnition Timing Control
. The ECM/PCM contains memories for basic ignition timing at various engine speeds and manifold air flow rates.
lgnition timing is also adjusted for engine coolant temperature.
. Aknockcontrol system was adopted which sets the ideal ignition timing for the octane rating ofthegasoline used.*3
Othgr Control Funqtions
1. Starting Control
When the engine is started, the ECM/PCM provides a rich mixture by increasing fuel injector duration.
2. Fuel Pump Control
. When the ignition switch is initially turned on, the ECM/PCM supplies ground to the PGM-Fl main relay that sup-plies current to the fuel pump for two seconds to pressurize the fuel system.. When the engine is running, the ECI\4PCM supplies ground to the PGM-FI majn relay that supplies current to the fuel
oumo.
. When the engine is not running and the ignition is on, the ECM/PCM cuts ground to the PGM-FI main relay which
cuts current to the fuel pump.
11-104
INPUTS
ENGINE CONTROL MODULE (ECMY
POWERTRAIN CONTROL MODULE (PCM) OUTPUTS

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.