
PGM-FI System
System Description
INPUTS
CKP/TDC/CYP Sensor
CKF Sensor
MAP Sensor
ECT Sensor
IAT Sensor
TP Sensor
Primary HO2S
Secondary H02S
vss
KS*5
BARO Sensor
ELD*6
Starter Signal
ALT FR Signal
Air Conditioning Signal
Ay'T Gear Position Signal*1
Baftery Voltage (lGN.1)
Brake Switch Signal
PSP Switch Signal
Fuel Tank Pressuae Sensor*4. *5
Countershaft Speed Sensor*1
Mainshaft Speed Sensor*r
OVER-DRIVE Switch Signal*s
ENGINE CONTROL MODULE (ECM)/
POWERTRAIN CONTROL MODULE (PCM) OUTPUTS
|iuel 1"j""- Th,rhg ""d Drrafr";-l
Et*-.nt"tdt"cont.orl
to,r*,c;;trffi;]
l.----.---:. .Lrgnrnon |lmrng Lonrror I
Ecir/PcM B*k',p Fr""il]
m;"t-ll-r*'io*l
Fuel Injectors
PGM-Fl Main Relay (Fuel Pump)
MIL
IAC Valve
Ay'C Compressor Clutch Relay
Radiator Fan Relay
Condenser Fan Relay
ALT
tcM
EVAP Purge Control Solenoid
Valve
Primary HO2S Heater
Secondary H02S HeaterEVAP Bypass Solenoid Valve*a *5
EVAP Control Canister Vent Shut
DLC
Lock-up Control Solenoid Valve*l
Shift Control Solenoid Valve*1
Ay'T Clutch Pressure Control
Solenoid Valve*1
D4 Indicator Light'1 *3, *a
D Indicator Light,l *5
OVER-DRIVE OFF Indicator
Lighl*t *:
*1: A/T {3:'97 model'2: M/f +4:'98 model*5: '99 - 00 models"6: USA
PGM-Fl System
The PGM-Fl system on this model is a sequential multiport fuel injection system.
Fuel iniecior Timing and Duration
The ECM/PCM contains memories for the basic discharge durations at various engine speeds and manifold pressure. The
basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors
to obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve (lAC Valve)
When the engine is cold, the Ay'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
o The ECM/PCM contains memories for basic ionition timing at various engine speeds and manifold air flow rates.
lgnition timing is also adjusted for engine coolant temperature.
. A knock control system was adopted which sets the ideal ig nition timing for the octane rating of the gasoline used.*s
Other Control Funstions
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 (ll). the ECMiPCM suppli€s ground to the PGM-FI main relay that
supplies current to the fuel pump for two seconds to pressurize the fuel system.
. When the engine is running, the ECM/PCM supplies ground to the PGM-FI main 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.
1 1-80
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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
Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1)
The Heated Oxygen Sensors (HO2S) detect the oxygen content in the exhaust gas and signal the ECM/PCM. In operation,
the ECM/PCM receives the signals from the sensor and varies the duration during which fuel is iniected. To stabilize the
sensor's output, the sensor has an internal heater. The Primary HO2S (Sensor 1) is installed in exhaust pipe A.
HO2S:
ztRcoNtAEI.IMENT
s€NsoRTERMINALSVOLTAGE IVI
HEATEBTERMINALS
The scan tool indicates Diagnostic Trouble Code (DTC) P0131: A low voltage
Oxygen Sensor (HO2S) {Sensor 1} circuit,
RICH - AIR. . LEANFUELNATO
problem in the Primary Heated
37 - 98 models:
HEATER
The MIL has been reoorted on.DTC P0131 is stoied.
Problem verification:1. Do the ECM/PCM Reset Pro-ceoure.Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on.Test-drive with the A/T in Eposition (M/T in 4th gear)Check the Primary HO2S{Sensor 1} output voltage withthe scan tool during accelera-tion using wide open throttle.
Intermittent f.ilure, system is OKat this time. Check fo. poor con-nections or loose wirer at C111(Primary HO2S, SeGor 1) and atrh€ ECM/FCM.
Check the fuel pressure (see page
11-178).
Repair the fuel supply system.
{To page 11'111}
1 1-1 10
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{From page 11-110}
Check tor a shorl in the HO2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor'1i 4P connector.3. Start the engine and let it idle.4. Check the Primary HO2S(Sensor 1)output voltage withthe scan tool.
Replace the HO2S {Sensor 1).Does it stay at 0.1 V or less?
Check for a short in the wir€(PH02S linel:1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector (D (16P), C (31P)*).
3. Check tor continuity betweenthe Primary HO2S {Sensor 1)4P connector terminal No. 1and body ground.
Repair short in tho wire botwesnthe ECM/PCM lD7, C16*) .nd th6Prim.ry HO2S (S€nsor 11.
Substituto a known-good ECM/PCM and recheck. ll 3ympiom/indication goes away. raplace th.origin.l ECM/PCM.
PRIMARY HO2S ls.n.or 'l I 4P CONNECTOR (Cl111
PHO2S ---'trwHTr T-T-l
T-1 1 2l
6tlr rlY r___J_J
L
Wire side of temale terminals
(cont'd)
11-111
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PGM-FI System
'99 - 00 models:
- The MIL has bsen reported on.- DTC P0131 ir storod.
Problem ve fication:1. Do the ECM/PCM Reset Pro-cedure,2. Start the engine. Hold theengine at 3,000 rpm with noload {in Park or neutral) untillhe radiator tan comes on.3. Check the Primary HO2S(Sensor 1) oltput voltage withthe scan tool during accelera-tion using wide op€n throttle.
Inl.rmittant failura, 3yrtam i! OKat thb tim.. Ch.ck tor poor con-nectiona oa looaa wlraa al C111{Pri|n.ry HO2S, Son3or 1l .nd .ttho ECM/FCM,
Does the voltage stay at 0.5 Vor less?
Check tho fuel pressure (see pago1r,178).
R.p.ir th. fu€l lupply ry!t.m.
Chock lor a short in tho HO2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor 1) 4P connector.3. St6rt the engine and lot it idle.4. Check the Primary HO2S(Sensor 1) output voltage withthe scan tool,
Does it stay 6t 0.5 V or less?Rephc. th6 HO2S (S.n3or 11.
Chock for a short in tho wirc(PHO2S lino):1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector C (31P).
3. Check tor continlity betweenthe Primary HO2S {Sensor 'l}
4P connector terminal No. Iand body ground.
Ragah rhort in tha wira balwoanth. ECM/PCM {Cl61 rnd thcPrirn.ry HO2S (S.n3or 11.
Substltut6 a known-good ECM/PCM and recheck. lf rymptom/indicrtion 00os away, raplaco thcoriginal ECM/PCM.
Primary Heated Oxygen Sensor (Primary HO2SI (Sensor 1l (cont'd)
PRIMARY HO2S (Son.or 1l aP CONNECTOR |C111)
PHO2S T--1rwHTr f-T---]
--1 1 2lI t--- 1t6)lslrlv L__r__J
_L
Wire side ol female terminals
11-112
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The scan tool indicates Diagnostic Trouble Code (DTC) P0132: A high voltage problem in the Primary HeatedOxygen Sensor {Primary HO2S) (Sensor 1) circuit.
'97 - 98 models:
PHO2S
IWHTIsG2IGRN/BLK}
Wire side ot female terminals
PCM CONNECTOR D {16PI
JUMPER WIRE
PHO2S IWHTISG2 IGRN/BLK}
Wire side of temale terminals
I
(cont'dl
11-113
Problem verification:1. Do the ECM/PCM Resot Pro,ceoute,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 Ay'T in Eposition (M/T in 4th gear).4. Check the Primary H02S{Sensor 1}output voltage withthe scan tool during decelera-tion using completely closedthrottle.
Intormittent l.ilure, 3ystem ia OKat thb timo. Chcck fo. poor con-nections 01 looso wi.es at C111{Prim!ry HO2S, Sensor 1} andECM/PCM.
Does the voltage stay at 1.0 V
Check for an open in th6 PrimaryH()2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor 1) connector-3. Connect the Primary HO25lSensor 1) 4P connector termi-nals No. 1 and No. 2 with ajumper wire.4. Turn the ignition switch ON (ll).5. Check the Primary HO2S(Sensor 1) output voltage withthe scan tool,
ls there 1.0 V or more?
Ch€ck for an opon in the wires(PHO2S, SG2linesl:1. Turn the ignition switch OFF.2. Connect PCM connector ter-minals D7 and Dl1 with a
3. Turn the ignition switch ON (ll).4. Check the Primary HO2S{Sensor 1) output voltage withthe scan tool.
Roprir opon in the wire betweontho PCM {D7 01 D11l and thePrimsry HO2S {S6nsor 1).
ls there 1.0 V or more?
{'97 model}
{To page 11-114)
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PGM-FI System
Primary Heated Oxygen Sensor lPrimary HO2S) {Sensor 1} {cont'dl
(From page'11-l13)
ECM/PCM CONNECTOR C {31PI
11-114
Ch.ck for an open in the wire(PHO2S linel:1. Turn the ignition switch OFF.2. Connect ECM/PCM connectorterminals C16 and C18 with a
3. Turn the ignition switch ON {ll).4. Check the Primarly H02S(Sensor 1) output voltage withthe scan tool.
R€p.ir open in the wire bqtw€enthe ECM/PCM (C161 and th€Primary HO2S (Sen.or'l).ls there 1,0 V or more?
Substitute a known-good ECM/PCM and rach€ck. lt 3ymptom/indication goos away, replacethe origin.l ECM/PCM.
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'99 - 00 modols:
Th6 Mll has b€on reDortod on.DTC ml32 is itorod.
Problem vorification:'1. Do the ECi!4/PCM Reset Procedure,Start the ongine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on.Check the Primary HO2SlSensor 1) output voltage withthe scan tool during decelela-tion using completely closedthroftle.
Int.rmitt .fi tailuro, syltom b OKat thit tima. Check for poor con-nactiona oi loo3a wirar !t Cltl(Primrry HO2S, S.nror 1) .nd .tth. ECM/FCM.
Doos the voitage stay at 1.5 Vor more?
Check for an opsn in the PrlmaryHO2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor 1)connector.3. Connect the Primary HO2S(Sensor 1) 4P connector t6rmi-nals No. 1 and No. 2 with a
iumperwire.4. Turn the ignition switch ON (ll).
5, Check the Primsry H02S(Sensor 1) output voltage withthe scan tool,
lsthere 1.5 V or more?
Check for an op6n in th6 wiro{PHO2S line):1. Turn tho ignition switch OFF.2. Connect ECM/PCM connectorterminals C16 and C18 with a
iumper wire.3. Turn the ignition switch ON lll).4. Check the Primary HO2S(Sensor 1) output voltage withthe scan tool.
Ropair opon in thc wire bc{w.cnthe ECM/PCM {Cl6}.nd thePrimary HO2S {S€nror 1}.ls there 1.5 V or more?
Substituto a known-good ECM/PCM snd rochock. lf 3ymptom/indicetion go€a awry, roplaca thoorigin.l ECM/PCM.
PRIMARY HOzS (S6n!or 1l aPCoNNECTOR lcltl)
Pt()2sIWHTIsG2{GRN/BTJ(I
Wire side of tem6le terminsls
ECM/PCM CONNECTOR C (31P}
IGRN/BLKI
JUMPER WIRE
Wire side ol temale t6rmin6ls
(cont'd)
-1 15
2789
/1617't819120A22
23E29g)31
PHO2S {WHTIsG2
11
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