Air Control HONDA CR-V 2000 RD1-RD3 / 1.G Owner's Manual

Troubleshooting
Troubleshooting Procedures (cont'dl
Symptom Chart
Listed below are symptoms and probable causes for problems that DO NOT cause the Malfunction Indicator Lamp (MlL) tocome on. lf the MIL was reported on, go to page 11-60.Troubleshoot each probable cause in the order listed (from left to right) until the symptom is eliminated,The probable cause and troubleshooting page reference can be found below.
Other Probable Causes for an engine that will not start:- Compression- Intake air leakage- Engine locked up- Timing belt- Starting system- Overheating- Battery
SYMPTOMPROBABLE CAUSE
Engine will not sta rt4, 2,3,5,20, 't5, 1
Hard starting2, 4, 12,17, 14, 't9
Cold fast idle too low7, a,9, 6, 17
Cold fast idle too high7,8,9,11,10
ldle speed fluctuates9,7,8, 't1, 10
Misfire or rough runningTroubleshoot for misfire on pages '11-126, 1|21LOl/\/ power2, 10,11, 13, '17, 18,20
Engine stalls2, 4, 12,1,20,9,5, 't6
Probable Cause List (For the DTC Ch8rt, see page ll-75.)
Probable CausePageSystem
Engine controt ruoaute (ecvtffi'I11-42
I 1-178Fuel oressure
PGM-Fl main relav
lgnition system
Crankshatt Position/Top Dead Center/Cylinder position sensor circuit
Intake Air Temperature (lAT) sensor ctrculr
ldle Air Control (lAC) Vatve
Fast idle thermo valve
ldle speed adjustment
Throttle body
Throftle cable
Manifold Absolute P."""rr"ffi
Throftle Position (TP) sensor
Barometric pressur" (gnno-
Ay'T gear position signal
Brake switch signal
Air Cleaner
Three Way Catalytic Converter (TWC)
Evaporative emission (EVAP) control
Contaminated fuel
1 1- 187
Section 4
5't1-'t31,146
6I 't-95
711-152
81'l-168
1 1- 169
1011-196'1111-'194
12'1 'l -90
1 1- 103
1411-137
15Section 14
161 1- 166
17r 1-194
181 1,199'1911-203
20
11-64
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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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Powertrain Control Module Terminal Arrangement -'97 Model
FCM CONNECTOR A (32P)NOTE: Standard battery voltage is 12 V.
Wire side of lemale terminals
f€rminalnumlreJWirecolor
Telminalnama
DescriptionSignal
YELlNJ4 (No.4 FUELINJECTOR)Drives No. 4 {uel injector.With engine running: duty controlled
2BLUlNJ3 (No.3 FUELINJECTOR)Drives No. 3luel injector.
REDlNJ2 {No.2 FUELINJECTOR)Drives No.2 tuel injector.
BRNlNJl (No. l FUELINJECTOR)Drives No. 1 fuel injector.
5BLK WHTSO2SHIC (SECONDARY
HEATED OXYGEN SENSOR HEATER CONTROL)
D ves secondary heated oxygensensor heater.With ignition switch ON {ll): battery voltageWith fully warmed up engino running: dutycontrolled
6BLKAr'YHT
PO2SHTC (PRIMARY
HEATED OXYGENSENSOR HEATERCONTROL}
Drives primary heated oxygensensor heater,With ignition switch ON lll): battery voltagewith fully warmed up engine running: dutycontroll6d
I8RN/BLKLGl (LOGIC GROUND}Ground forthe PCM control circuit.Less than 1.0 V at all times
10BLKPG1 lPOWER GROUND}Ground for the PCM power circuit.
l1YEUELKIGPl lPOWER SOURCE}Power source for the PCM controlcircuit.
With ignition switch ON (ll): battery voltageWith ignition switch OFF: 0 V
12BLI(BLUIACV {IDLE AIRCONTROL VALVE}Drives IACV.With €ngine running: duty controlled
REDryEL
PCS (EVAP PURGECONTFOL SOLENOIDVALVE)
Drives EVAP purge controlsolenoid valve.
With engine running, engine coolantbelow 154'F (68"C): battery voltageWith engine running, engine coolantabove 154"F (68"C): duty controlled
16GRN/VELFLR (FUEL PUMP RELAY)Drives Iuel pump relay.0 V for two seconds after turning ignition
switch ON lll), then battery voltage
118LI(REDACC (A,/C CLUTCHRELAY}Drives Ay'C clutch relay.With comoressor ON: 0 VWith compressor OFF: baftery voltage
18GRN/ORNMIL (MALFUNCTION
INDICATOR LAMP}Drives MlL.With MIL turned ON: 0 VWith MIL turned OFF: baftery voltage
19*WHT/GRNALTC (ALTERNATOR
CONTROL}Sends alternator control signal.With tully warmed-up engine running:
battery voltageDuring driving with smallelectrical load:0 '
20YEUGRNICM (IGNITION CONTROLMODULE)Sends ignition pulse.With ignition switch ON (ll): baftery voltageWith engine running: pulses
22BRN/BLKLG2 (LOGIC GROUND}Ground tor the PCM control circuit.Less than 1.0 V at alltimes
23BLKPG2 {POWER GROUND}Ground lor the PCM power circuit.
24YEUBLKIGP2 {POWER SOURCE}Power source for the PCM controlcircuit.
With ignition switch ON (ll): battery voltage
With engine switch OFF: 0 V
27GRNFANC (RADIATOR FANCONTROL)Drives radiator {an relay.With radiator fan running: 0 VWith radiator fan stopped: baftery voltage
*: USA
{cont'd)
11-67
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Troubleshooting
Engine/Powertrain Control Module Terminal Arrangement - '98 - 00 Models
(cont'd)
ECM/PCM CONNECTOR B {25PI
Wire side of female terminalsECM/PCM CONNECTOR B I25PI
*2t MlT*3: '98 model"4: '99 - 00 models
NOTE: Standard baftery voltage is l2
Ierminalnumb€tWire colorTerminsl nameDescriptionSignal
1YEUBLKIGPl (POWER SOURCE)Power source for the ECM/PClvlcontrol circuit.withagewith
ignition switch ON (ll): battery volt-
ignition switch OFF:0 V
BLKPG1 (POWER GROUND}Ground for the ECM/PClvl controlcircuit.Less than 1.0 V at all times
REDlNJ2 (No. 2 FUEL INJEC-roR)Drives No. 2 Iuel injector.With engine running: duty controlled
BLUlNJ3 1No. 3 FUEL INJEC-TOR)Drives No. 3Iuel jnjector.
YELlNJ4 {No.4 FUEL INJEC-TOR)Drives No. 4 fuel injector.
8*1WHTLS- (A"/T CLUTCH PRES.SURE CONTROL SOLE,NOID VALVE _ SIDE)
A,/T clutch pressure controlsolenoid valve power supplynegative terminal.
With ignition switch ON (ll): dutycontrolled
9YEUBLKIGP2 IPOWER SOURCE)Power source for the ECN,I/PCMcontrol circuit.With ignition switch ON (lll: bafteryvoltageWith ignition switch OFF:0 V
10BLKPG2 (POWER GROUND}Ground for the ECM/PCM controlcrrcurt.Less than '1.0 V at all times
' BRNlNJl (No. 1 FUEL INJECTOR)Drives No. l tuel injector.With engine running: duty controlled
YEUGRNrcM {rGNrTroN coN-TROL MODULE)Sends ignition pulse.With ignition switch ON (ll): batteryvoltageWith engine running: pulses
17*1REDLS+ (A,,IT CLUTCH PRESSURE CONTROL SOLE-NOID VALVE + SIDE)
A,/T clutch pressure controlsolenoid valve power supplypositive terminal
With ignition switch ON (ll): dutycontrolled
19*.PNK
ODIND (OVER-DRIVE
OFF INDICATOR}Drives OVER-DRIVE OFFindicator light.With OVER-DRIVE OFF indicator lightturned ON: 0 VWith OVER-DRIVE OFF indicator lightturned OFF: battery voltage
20BRN/BLKLG1 (LOGIC GROUND)Ground for the ECM/PCM controlcircuit.Less than 1.0 V at all times
WHT/BLUVBU (VOLTAGE BACKUP)Power source for the ECM/PCMcontrol circuit.Power source forthe DTC memory.
Battery voltage at all times
22BRN/BLKLG2 (LOGIC GROUND)Ground for the ECN4/PCM controlctrcutt,Less than 1.0 V at all times
23BLVBLUIACV {IDLE AIR CON.TROL VALVE)Drives IAC valve.With engine running: duty controlled
11-72
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ECM/PCM CONNECTOF C (31PI
Wire side o{ female terminal€ECM/PCM CONNECTOR C (31P)NOTE: Standard battery voltage is 12 V.
TermidalD.3criptionSignal
8LI(WHTPOzSHTC {PRIII4ABY HEATEDOXYGEN SENSOR HEATERCONTROL)
Drivss prim6ry h$ted oxygsn sensorWilh ignition switch ON (ll): baneryvoltsgeWith ftrllywarmsd up €ngine runnang: duty
2"WHT/GBNALTC (ALTERNATOR CON,TROL)Sonds alternalor control signsl.With fully wafmod up €ngine rnningr ban€ryvoltagoDu ng driving with small elsctrical lo6d: 0 v
3'1FED/8LUKS (KNOCK SENSOR)Dstects KS signal.With engine knockang: pulses
5WHT/REDALTF (ALTERNATOR FR SIG-NAL}Detects alternator FR signal.Wth fullywarmed up €ngine running:0 V-batteryvoltag€ {d€pending on slsctrical load)
1GRN,4trHTSG1 (SENSOR 680UND}Ground for l/tAP sensor.L€ss than 1.0 v 6t all times
8BLUCKPP (CKP SENSOF P SIDE)Dat€cls CKP s6nsor.With €ngin€ runningr puls€s
9CKPI.,I| {CKP SENSOF M SIDE)Ground for CKP s€nsor.
15PHO2S {PRIMARY HEATEDOXYGEN SENSOR, SENSOR 1)Detocts pfimary he6t6d oxygen ssnsor
{sonsor 1)signal.with ihfottls fully opened from idle with fully,
walm6d up engins: above 0.6 VWith throttlo quickly clossd: below 0.4 v
17RED/GRNMAP (MANIFOLD ABSOLUTEPRESSURE SENSOR)
D6tects MAP s€nsor sign6l.With ignition switch ON (ll):about 3 VAt idls: aboul 1.0 V {dspsnding on engine speed)
18GRN/BLKSG2 (SENSOB GNOUNDiLsss than 1.0 V at all tim€s
19YEUBEDVCCl {SENSOR VOLTAGE)Power soufce to MAP s€nsor.With ignition switch ON (ll): about 5 VWith ignition switch OFF:0 V
20GRNTDCP {TDC SENSOR P SIDE)Derecis TDC sensor.With engine funning: Pulses
2lREDTDCM ITDC SENSOR M SID€)Ground for TDC sensor.
22BLU/REDCKFP (CKF SENSOR PSIDE)Dstscts CKF s€nsor.With sngins running: pulsss
23BLU/WHTVSS (VEHICLE SPEED SEN-soR)Dstscrs vss signal.With ignition switch ON (ll)and front wheelsrotaringrcyclss 0 v- 6bout 5 V or ban€ry voltage
25RED//ELIAT (INTAKE AIR TEMPERA'TURE SENSOB)Detacts IAT sensor signal.With igniiion switch ON (ll): about 0.1 - 4.8 V(d€p€nding on iniate air t€mp€raturc)
26REO/WHTECT {ENCINE COOLANTTEMPERATURE SENSOR)oetscts ECT sensor signal.With ignition switch ON (ll): about 0.1 4.8 V
{doponding on 6ngin€ coolanl lemper6tu16)
27RED/BLKTPS (THROTTLE POSITIONSENSOR)Dotects TP sensor signrl.with rhrottls fully op€n: aboui 4.8 vwith throtrl6 fullyclosed: about 0.5 v
2AYEUBLUVCC2lSENSOR VOLTAG€}Provid€s s€nsor voltage.With ignilion switch ON (ll): about 5 VWhh ignition switch OFF: 0 V
29YELCYPP ICYP SENSO8 P SIDE)Dsrscts CYP sensor.With €ngins runningr pulsss
30BLKCYPM (CYP SENSOR M SIDE)Ground for CYP sansor.
31WHT/REDCKFM {CKF SENSOR M SIDE)6.ound lof CKF ssnsor signal.
11. AfT 13. '94 model'2:M/T 14:'99- 0o modsls.5: USA
(cont'd)
11-73
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Troubleshooting
Diagnostic Trouble Code (DTCI Ghart (cont'd)
r: These DTCS will be indicated by the blinking oJ the Malfunction Indicator Lamp (MlL) with the SCS service connectorconnected.**: The Di (E)*5 indicator light and the Malfunction tndicator Lamp (MlL) may come on simultaneously.*1: A[f *3;'97 model *5: '99 - 00 models*21M/f *4: '98 model
11-78
DTC
{MlL indication}Detection ltemProbable CausePagc
P1336 154)Crankshaft SpeedFluctuation SensorIntermittent Interruption
. CKF sensor
11-142
P1337 i54)Crankshaft SpeedFluctuation SensorNo Signal
CKF sensorCKF sensor circuitECM,FCM11-142
P1359 (8)Crankshaft Position/Too DeadCenter Sensorrcylinder PositionConnector Disconnection
' CKP/TDC/CYP sensor circuit11-146
P1361 (8)Top Dead CenterSensor IntermittentInterruption11-131
P1362 (8)Top Dead CenterSensor No SignalTDC sensorTDC sensor circuitECM/PCM11-131
P1381 (9)Cylinder Position SensorIntermittent Interruption
. CYP sensor11-131
P1382 (9)Cylinder Position SensorNo SignalCYP sensorCYP sensor circuitECM/PCM11-131
P1456n.* {90}
Evaporative EmissionControl System Leak Detected(FuelTank System)
Fuelfill capVacuum connectionFueltankFuel tank prossure sensorEVAP bypass solenoid valveEVAP two way valveEVAP control canister vent shut valveEVAP control canisterEVAP purge controlsolenoid valve
11-213
Pr457n.s {90)
Evaporative EmissionControl System Leak Detected(EVAP Control Canister Svstem)
Vacuum connectionEVAP control canisterFuel tank pressure sensorEVAP bypass solenoid valveEVAP two way valveEVAP control canister vent shut valveFueltankEVAP purge controlsolenoid valve
11-219
P1508 (14)ldle Air ControlValve CircuitFailure
IAC valveIAC valve circuitECM/PCM11-152
Pr607(-)Engine Control Module,PowertrainControl Module Internal CircuitFailure A
. ECM,FCM11-147
P1705P1706P1753P1758P1768
AutomaticTransaxle
Section '14
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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.
brARn
t.-OotO tw"t Describes the conditions or situation to start a troubleshooting flowchart.
FcTloNl 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.
fS-OPl The end of a series of actions and decisions, describes a final repair action and sometimes directs you to
(bold type) 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 Module (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,
o "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. ln simple electronics, this usually means something won't
work at all. In complex electronics (like ECM'S/PCM'S), this can sometimes mean something works, but not the way it's
suooosed to.
LOOSE
11-79
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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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