Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors iscutoffto improvefuel economyat
speeds over 970 rpm ('97 - 98 models), 920 rpm ('99 - 00 modelsl.
. Fuel cut-off action also takes place when engine speed exceeds 6,500 rpm ('97 - 98 models), 6900 rpm ('99 - 00
models), regardless of the position of the throttle valve, to protect the engine from over-rewing.
With Ay'T model. the PCM cuts the fuel at engine speeds over 5,000 rpm when the vehicle is not moving.*'
4,./C Comoressor Clutch Relav
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 a smooth transition to the Ay'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,
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.
PCM Fail-saf e/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-pre
grammed value for that sensor that allows the engine to continue to run.
2. Back-up 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 IMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the MIL and stores the DTC
in erasable memory. When the ignition is initially turned on {ll), the ECM/PCM supplies ground for the MIL for two
seconds to check the MIL bulb condition.
4. Two Trio Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S*1, fuel metering-related. idle control
system, ECT sensor 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 (ll) 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 {'97 model)
A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles.
or TWC deterioration is detected during 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.
*1: '97 - 98 models*2: '99 - 00 models
5.
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PGM-FI System
Powertrain Control Module {PCM} -'97 Model
NOTE: lf this symptom is intermiftent, check for a loose fuse No. 25 METER (7.5 A) in theunderdash f{rse/relay box, a poor connection at PCM terminal A18, or an intermittentopen in the GRN/ORN wire between the PCM (A18) and the gauge assembly.
PCM OON ECTOR A {32P}
Wire side of female terminals
PCM CONNECTOR A {32PI
Wire side ot temale terminals
11-42
The Malfunction lndicator LamD(MlL) nev6r comes on {even lortwo seconds) after ignition isturned on (lll, or it's on dimlyand flickers.
Turn the ignition switch ON {ll}.
- Rep.ir short or opon in thowire batween No. 25 METER(7.5 Alfuso and gauge a$€m-bty.- R6pl.c€ No. 25 METER 17.5 Alfus€.
ls the charging system light on?
Try to stan the engine.
Does the engine start?
Chock tor.n open in th6 wire3{PG1, PG2linesl:1. Turn the ignition switch ON (ll).2. Measure voltage betweenbody ground and PCM con-nector terminals A10 and A23individually.
Check for an op€n in the wir6 orbulb (MlL lin€l:1. Turn the ignition switch OFF.2. Connect the PCM connectorterminal A18 to body groundwith a iumper wire.3. Turn the ignition switch ON {ll).
n€peir open in tho wirelslhwoon PCM and Glol (loc!t.d
at thc tha.mo3tat houling thrthtd moro th.n 1.0 V.
ls thore l€ss than 1.0 V?
Substituto . known-good PCMand r€check. ll symptom/indica-tion goss away, rcplaca the origi-nal PCM.
- R6pai. open in th. wileibelwoon rcM lAl8l dnd g.ugea3rombly.- Roolac€ the MIL bulb.
ls the MIL on?
Substitut6 a known-good PCMand rocheck. ll 3ymptom/indica-tion goes away, replace the o.igi-n.l PCM.
PGl IBLKI
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PGM-FI System
Tho Maltunction Indicator Lamo(MlL) n6Yor como3 on leven lortwo laconds) rft6r tho ignhion isturnod ON {lll.
Turn th6 ignition switch ON (ll).
- Repair lhort or opcn in thowire between the No. 25METER 17.5 Al fu3e snd thegauge assembly.- Repl.co the No. 25 METER17.5 Al fus€.
ls the low oil pressure light on?
Try to start the engine.
Chock for an opsn in th€ wiro orbulb {MlL line,:1. Turn the ignition switch OFF.2. Connect the ECM/PCM con-nector terminal A18 to bodyground with a iumper wire.3. Turn the ignition switch ON (ll).
Rep.ir open in the wi.osbotween the ECM/FCM lA18land the gaugo rasombly.Roplece the MIL bulb.
ls th6 MIL on?
Substitute a known-good ECM/PCM and rochock. lf rymptom/indication goes eway, replacetho o gind ECM/PCM.
Turn the ignition switch OFF.Inspect the Fl E/M 115 A) tusein the undeFhood fuse/relaybox.
- Repair short in the wirebetween lhe Fl E/M (15 AlfusG and the PGM-Fl m.in.slay.- Roplsce th€ Fl E/M (15 Alfu3€.
Inspect the No. 13 FUEL PUMP(15 A) fuse in the under-dashfuse/relay box.
- Repair short in th6 wirebetween tho No. 13 FUELPUMP 115 A) luse and thePGM-FI main .elay.- ReDlace tho No. 13 FUELPUMP 115 Al tuse.
Engine Gontrol Module/Powertrain Control Module (ECM/PCM) -'98 - 00 Models
NOTE:. lf this symptom is intermittent, check tor:- A loose Fl E/M {15 A) fuse in the under-hood fuse/relay box- A loose No. 25 METER {7.5 A) fuse in the under-dash fuse/relay box- A loose No. 13 FUEL PUMP (15 Alfuse in the underdash fuse/rolay box- An intermiftent short in the wire between the ECM/PCM (A18) and the gauge assem-
- An int€rmiftent short in the wire between the ECM/PCM (C19) and the MAP sensor- An intermiftent short in the wire between rhe ECM/PCM (C28), the TP sensor, theEGR valve lift sensor and/or {uel tank Dressure sensor- A laulty PGM-FI main relay
ECM/PCM CONNECTOR A (32P}
Wire side of female terminals
(To page 11-871
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PGM-FI System
Elestrical Load Detector (ELDI (USA Modell
The scan tool indic€tes Diagnostic Trouble Code (DTC) P1297: A low voltage problem in the Electrical Load
Detector (ELD) circuit.
'97 model:
ELD 3P CONNECTOR {C354I
--+-l1L2l3l
ler-
O) tcnrulaeot
Y
Wire side ot female terminals
PCM CONNECTOR D I16P)
Wire side of female terminals
Problem vsriticltion:1. Do the PCM Feset Procedure.2. Start the engine.3. Turn on the headlights.
Intormittent lailuic, 3vstom k OKat thk time. Ch.ck tor poor con-nections or loose wiro3 at C127(loc.ted on PCM b.sckot), C354{ELO, .nd at tho FCM.
ls DTC P1297 indicated?
Ch.ck for 3hort in lho ELD:Measure voltage between bodyground and the ELD 3P connectorterminal No.3.
ls there approx. 4.5 V?
Check for a short in tho wire IELlinel:1. Turn the ignition switch OFF.2. Disconnect PCM connector D(16P).
3. Check for continuity betweenbody ground and PCM connector terminal D16.
Rcpair 3hort in tho $rire botwo€nthe PcM lDl6l and tho ELD.
Substituto a known-good PCMand rocheck. lf 3ymptom/indic.-tion goos !w!y, repl.ce the origi-nal PCM.
1 1-138
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98 - 00 mod6l3:
- OTC P l1€7 is 3tored.
Problcm vcrificrtion:1. Do the ECM/PCM Reset Pro-cedure,2. Start the engine.3. Turn on the headlights.
Intcrmittent tailuro, ryrtom ir OK!t thi3 timo. Ch.ck tor poor con-nectiont or looao wire! at CXl54IELD) rnd at rh6 ECM/PCM,
ls DTC P1297 indicated?
Chock for 3hort in tho ELD:Measure voltage between bodyground and the ELD 3P connectorterminal No.3.
ls there approx. 4.5 V?
Chcck lor a 3horl in tho wiio (EL
linol:1. Turn the ignition switch OFF.2. Disconnect ECM/PCM con-nector A (32P).
3. Check for continuity betweenbody ground and ECM/PCMconn€ctort€rminal A30.
Ropair shon in thc wira botwocntho PcM (A301 rnd rho ELD.
Sub.tituto a known.good ECM/PCM .nd rocheck. ll lymptom/indication gocs .w!y. replsceth6 o.iginal ECM/PCM,
ELD 3P CONNECTOR ICAs4I
f_l,I 2l3l-
l--- r'.
&) iGRN/RED)
T
Wire side of temale terminals
ECM/PCM CONNECTOR A I32P)
Wire sid6 of female terminals
(cont'd)
-13911
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PGM-FI System
Electrical Load Detestor (ELDI (USA Model) (cont'dl
The scan tool indicates Diagnostic Trouble Code {DTC) Pl298; A high voltage problem in the Electrical Load
Detector (ELD) circuit.
97 modsl:
ELD 3P CONNECTOR {C35,'I
Wire sido oI lemale terminals
r lzlrl--T_ow
/6 IBLKI
Y
Repail op€n in th. wire b€tws€ntho No. 15 ALTERNATOR SPSENSOR 17.5 A) tuse in theunder-dlrh fuso/r.lay box andth6 ELD.EL {GRN/NEDI
PCM CONNECTORS
Problam verification:1. Do the PCM Reset Procedure.2. Start the engine.3. Turn on the headlights.Intermittent tailuro, systcm is OK.t this time. Chack for ooor con-noction! or looro wire3 at C127{locaied on PCM brackot), C35{{ELDI and .t tho PCM.
Chack for an opan in tho wilellGl linol:1. Turn thg ignition and head-lights OFF.2. Disconnect the ELD 3P connector.3. Turn the ignition switch ON {ll).4. M6asure voltage b€tw€enbody ground and the ELD 3Pconnoctor terminal No. 1.
Chock lol !n open in the wireIGND linel:'1. Turn the ignition switch andheadlights OFF.2. Disconnect the ELD 3P conneqor,3. Check for continuity betweenbody ground and the ELD 3Pconnector terminal No. 2.
Ropair opon in th6 wi.e betweonth. ELD connector rnd GiO2,
Ch.ck lo. an open in th€ wiro (EL
line):Check for continuity between theELD 3P connector terminal No. 3and PCM connector terminal 016.
Chock for . malfunction in theELD:1. Reconnect the ELD 3P con-neclor,2. Start the engine and allow itto idle.3. While measuring voltagebetween PCM connector terminals 016 and A9. turn theheadlights on (low).
ls there continuityT
R6pafu op6n in tho wire betweenthe PCM {D161snd th6 ELD.
Subltituto . known-good PCMand rachock, f symptom/indic.-tion goes awry, ropl.ce the origi-n.l PCM.
Does the voltage drop?
Wire side of lemale terminals
11-140
Wire side of lemale terminals
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38 - 00 modeb:
Problem verification:1. Do the ECM/PCM Reset Proceoure.2. Stan the engine.3- Turn on the headlights.Intermittent feilure, sysl.m is OKat this time. Check for ooor con-nections or loose wires at C354(ELDI and at the ECM/PCM.
ls DTC P1298 indicated?
Check lor an open in the wire(lG1 line):'1. Turn the ignition and head-lights OFF.2. Disconnect the ELD 3P connector.3. Turn the ignition switch ON (ll).
4, Measu re voltage betweenbody ground and the ELD 3Pconnector terminal No. '1.Reprir open or short in th6 wirebotweon the No. 15 ALTERNA-TOR SP SENSOR {7.5 Al fuse inthe under-drah fuse/relay boxand the ELD.
Check tor an opon in tho wire{GND line}:1. Turn the ignition switch andheadlights OFF.2. Disconnect the ELD 3P connector.3. Check for continuity betweenbody ground and the ELD 3Pconnector terminal No. 2,
Repair opon in the wire betweenthe ELD conneclor and GilO2.
Ched( fo. an op€n in the wir€ (EL linel:Check for continuity between theELD 3P connector terminal No. 3and ECM/PCM connector termi-nalA30.
Repair op€n in tha wile botwecnthe EcM/PCM lA30l .nd rhe ELD.
Check for s malfunction in lhe ELD:1. Reconnect the ELD 3P con-nector.2. Start the engine and allow itto idle.3. While measuring voltagebetween ECM/PCM connectorterminals A30 and 820, turnthe headlights on (low).
Substiiute a known-good ECM/PCM and recheck. It symptom/indication goos away, replacethe original ECM/PCM.
ELO 3P CONNECTOR {c35/rl
Wire side of female terminals
Wire side of female terminals
Wire side ot temale terminals
ELD 3P CONNECTOR {C35,lt
EL IGRN/RED}Wire side of femaletermrnars
ECM/PCM CONNECTORS
A l32P)
11-141
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ldle Control System
ldle Control System
I P0505 | The scan tool indicates Diagnostic T.ouble Code (DTCI PO5O5: ldlecontrol svstem mattunction.
NOTE: lf DTC P1508 is stored at the same time as DTC P0505, troubleshoot DTC P1508 first. then troubleshoot DTC p0505.
Possibls Cause
. IAC valve mechanical malfunction. Throttle body clogged port, improper adlustment. Intake manifold gasket leakaging. Intake air hose loose leakaging. Vacuum hose leakaging
a ECT sensor incorrect output. Throttle Position sensor incorrect output
Troubleshooting Flowchart
The MIL has been reDorted on.DTC P0505 is sto.ed.
Problem verificationi1. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator Ian comes on, thenlet it idle.2. With the scan tool, check thelollowing items.- Throttle position should beapprox. 10% with the throt-tle {ully closed.- Engine coolant temperature shorJld be 194 - 205'F(90 - 96"C).lf they are not within thespec., repair the faulty sen-sor circuit.3 Check the engine speed atidle with no-load conditions:headlights, blower fan. reardefogger, radiator lan, and airconditioner are not operaling,
Inte.mittent failure. syltem is OKat this time.ls it 750 {730)* i 50 rpm?
ls il 700 (680)' rpm or less?
{To page 11-151)(To page 1'l-151)
l:'99 - 00 models
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