2003 HONDA CIVIC Control

SymptomDiagnostic procedureAlso check torDifficult to refuel(MlL works OK. no DTCS set)
1. Testthefuel tank vapor control valve{seepage 1'l-
2. 1471.
Inspect the fuel tank vapor control signal tube
3. between the fuel pipe and the fuel tank vapor
control valve.
4. Inspect the fuel tank vapor vent tube between the
EVAP canister and the fuel tank vapor control valve.
Check the EVAP canister.
Malfunctioning gas
station filling nozzle.
Fuel overflows during
refueling(No DTCS set)
Replace the fuel tank vapor control valve (see page '1 1
189).
Malfunctioning gas
station filling nozzle.
11-11

Fuel and Emissions Systems
System Descriptions
Electronic Control System
The functions of the fuel and emlssion control systems are managed by the engine control module (ECM).
Fail-safe Function
When an abnormality occurs in the signal from a sensor, the ECI\4 ignores that signal and assumes a pre-programmed
value for that sensor that allows the enqine to continue to run.
Back-up Function
When an abnormality occurs in the ECM, the injectors are controlled by a back-up circuit independent of the system to
permit minimal driving.
Self-diagnosis
When an abnormality occurs in the signal from a sensor, the ECM supplies ground for the malfunction indicator lamp
{MlL) and stores the diagnostic trouble code {DTC) in erasable memory. When the ignition is first turned on, the EClvl
supplies ground to the l\4lL for 15 to 20 seconds to check the M lL bulb condition.
Two Driving Cycle Detection Method
To prevent false indications, the "two driving cycle detection method" is used for some self-diagnostic functions.
When an abnormality occurs, the ECM stores it in its memory. When the same abnormality recurs afterthe ignition
switch is turned OFF and ON (ll) again, the ECM turns on the MlL.
\
11-12
\.
\{

ECM Data
You can retrieve data from the ECI\4 by connecting the OBD ll scan tool or the Honda PGM Tester to the data link
connector (DLC). The items listed in the table below conform to SAE recommended practice. The Honda PGM Tester
also reads data beyond that recommended by SAE to help you find the causes of intermittent problems.
The "operating values" listed are approximate and may vary depending on the environment and the individual
vehicle.
Unless noted otherwise, "at idle speed" means idling with the engine completely warmed up in the neutral position,
and the A,/C and all
Diagnostic
Trouble Code(DTC}
lf the ECM delects a problem, it will store it as a code
consisting of one letter and four numbers. Depending on
the problem, an SAE-defined code (Poxxx) or a Honda,
defined code {P1xxx) will be output to the tester.
The ECI\4 computes engine speed from the signals sent
from the crankshaft position (CKP) sensor. This data is
used for determining the time and amount of injected fuel.
detected, there is no
ourpul.
lf no problem is YES
Nearly the same as
tachometer indication
At idle speed;
The ECM converts pulse signals from the vehicle speed
sensor (VSS).Nearly the same as
speedometer
indication
Manifold
Absolute
Pressure(MAP)
The absolute pressure caused in the intake manifold by
engine load and speed.
With engine stopped: YES
Nearly the same as
almospnenc pressure.
At idle speed: about
20 4'1 kPa(150 310 mmHg,
6- 12 in.Hq).0.7 1.3 V
The ECT sensor converts coolant temperature into voltage
and signals the ECM. The sensor is a thermistor whose
internal resistance changes with coolant tempetature. The
ECM uses the voltage signals from the ECT sensor to
determine the amount of injected fuel.
With cold engine:
Same as ambient
temperature and IAT
With engine warmed
up; about 116 2'12"F
100'c).0.5-0.8 v
Air Fuel Ratio The A,/F sensor detects the oxygen content in the exha ust 0.0 - 1 .25 V(Ay'F) Sensor. gas and sends voltage signals to the Eclvl, Basedonthese 8.0 11.0mA(PGM(Sensor 1) signals, the ECM controls the airlfuel ratio. When the I Tester)
oxygen content is high (that is, when the ratio is leaner At idle speed:
than the stoichiometric ratio), the voltage signal is Iower. about 0.1 0.9 V
When the oxygen content is low (that is, when the ralio is
richer than the stoichiometric ratio). the voltage signal is
higher. The A'lF sensor signals are electrical current that
are indicated as voltaqe on the
The HO2S detects the oxygen content in the exhaust gas
and sends voltage signals to the ECM. Based on these
signals, the ECM 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 oxygen content is low (that is, when the ratio is
richer than the stoichiometric ratio), the voltage signal is
Secondary
Heated
Oxygen
Sensor(Secondary
H02S,
Sensor2)
0.0 1.25 V NO
At idle speed:
about 0.1 0.9 V
(cont'd)
11-13

Fuel and Emissions Systems
System Descriptions (cont'd)
ECM Data (cont'd)
w
DataDescriptionOpera'ting ValueFreeze Data
Fuel System
Status
Fuel system status is indicated as "open" or "closed".
Closed: Based on the A,/F Sensor output, the ECM
determines the airlfuel ratio and controls the amount of
injected fuel.
Open: lgnoring Ay'F Sensor output, the ECM refers to
signals from the throttle position {TP), manifold absolute
pressure (MAP), intake air temperature (lAT), barometric
pressure (BARO), and engine coolant temperature (ECT))
sensors to control the amount of iniected fuel.
At idle speed: closedYES
Short Term
FuelTrim
The airlfuel ratio correction coefficient for correcting the
amount of injected fuel when the fuel system status
is "closed." When the ratio is leaner than the
sloichiometric ratio, the ECM increases short term fuel
trim gradually, and the amount of iniected fuel increases.
The airlfuel ratio gradually gets richer, causing a lower
oxygen content in the exhaust gas. Consequently, the
short term fuel trim is lowered, and the ECM reduces the
amount of injected fuel.
This cvcle keeps the airlfuel ratio close to the
stoichiometric ratio when in closed loop status.
o.7 1.5YES
Long Term
Fuel Trim
Long term fuel trim is computed from short term fuel trim
and indicates changes occurring in the fuel supply system
over a long period.
lf long term fuel trlm is higher than 1.00, the amounl of
injected fuel must be increased. lf it is lower than 1.00, the
amount of injected fuel must be reduced.
0.8 1.2YES
Intake Air
Temperature
{IAT)
The IAT sensor converts intake air temperature into
voltage and signals the ECM. When intake air
temperature is low, the internal resistance ofthe sensor
increases, and the voltage signal is higher.
With cold engine:
Same as ambient
temperature and ECT
YES
Throttle
Position
Based on the accelerator pedal position, the opening
anole of the throttle valve is indicated.
At idle speed:
about 10 %
YES
lgnition
Timing
lgnition timing is the ignition advance angle set by the
ECM. The ECM matches ignition timing to driving
conditions.
At idle speed: 8" t 5"
|' tuL wnen rne >L)
service signal line is
jumped with the Honda
PGM Tester
NO
Calculated
Load Value
(cLV)
cLV is the enoine load calculated from IMAP data.At idle speed:
12 34%
At 2.500 rpm with no
toao:'t4- 34%
YES
11-14
\.,
ra

EVAPCANISTE6PURGE VAIVE
EVAPCANISTERVENTSHUTVATVE
sotENotovAtvE
A/FSENSOR
A/FSENSOR(sENSOn 1)
CMP SENSOF A
VIC OIL CONTROLSO!ENOIDVALVE
wEcorlPRESSUSE SWTICH
VTEC SOLENOID
{cont'd)
11-17
No. 1 IGNITION COIL
No.2lGNlllON COIL
No. 3 IGNITION COIL
No. a IGNITION COIL

ECM Inputs and Outputs at Connector A (31P)
NOTE: Standard battery voltage is 12 V.
1AFS]TC2
]GP23IGPl^:^ I -:,6AFS+1
CKPIKS
'10
SG2t112ACV15TPST6AFS_18
VSS
19IVAP2Avcc221vccl
22
HTC+
23LG225CMPA
26CMPB(rDc)
27tGPts,l28rcPts329tGPts230GPLS 1
Wire side ol female terminals
Terminalnumb€rWho colorforminal nameDescriptionSignal
ELKAVHTAFSHTC (AIR FUEL RATIO(4./F)SENSOR HEATERCONTROL}
Drives Ay'F sensor heaterWith ignit'on switch ON {ll): battery voltageWith fully warmed up engine runnang: 0 V
2YEUBLKIGP2 (POWEB SOURCE)Power source for the ECMcircuitWith the ignition switch ON 1ll): battery voltageWith the ionition switch OFF: about 0 V3YEUBLKIGPl {POWER SOURCE)Power source for the ECMWith the ignition swatch ON {ll): battery voltageWith the ionition switch OFF: about 0 V4BLKPG2 (POWER GROUNDGround forthe ECM circuitLess than 1.0 V at all times5BLKPG1 (POWER GROUNDGround forthe ECM circuitLess than 1.0 V at all times6REDAFS + (AIR FUEL RATIO(A,/F}SENSOR, SENSOR 1+ stDE)
Detects Ay'F sensor{sensor 1) signal
18LUCKP (CRANKSHAFTPOSITION SENSOR)Detects CKP sensor signalWith engine running: pulses
9BED/BLU)K SENSOB)Detects knock sensor siqnalWith enqine knocking: pulses10YEL2 {SENSOR;ROUND);ROUND)Sensor qrounrLessthan 1.0V at elltimesG1 {SENSORSensor qroun(Lessthan 1.0V at alltimes12BLIVREDIACV (IDLE AIR CONTROL(IAC)VALVE)Drives IAC valveWith engine runningr duty controlled
RED/BLKTPS (THROTTLE POSITIONSENSOR)Detects TP sensor signalWith throttle fully open: about 4.8 VWith thronle fullv closed: ahout 0-5 VREDI/ELAFS (AIR FUEL RATIO(4,/F)SENSOR, SENSOB 1SIDE)
Detects !y'F sensor(sensor 1)signal
18WHT/GRNVSS (VEHICLE SPEEDSENSOR)Detects VSS signalWath ignition switch ON (lli and front wheelsrotating: cycles from about 0 V to about 5 V or
(cont'd)
11-19

Fuel and Emissions Systems
System Descriptions {cont'd)
ECM Inputs and Outputs at Connector A (31P)
\. il
Wire side of female terminals
\.
1AFS]TC2
GP2
3IGPl4PG25PG.16AFS+1
CKP
IKS
10SG211sG1
12IACV
'15
TPS16AFS_18
VSS
19IVAP20vcc221vccl
22AFSHTC+
23LG225
Ct\.4PA
26CMPB(rDc)
27IGPLS428IGPLS329IGPLS230IGPLS,I
NOTE: Standard battery voltage is 12 V.
JorminalnumberWirecolor[€rminal namoDescriptionSignal
19GRN/REDMAP (MANIFOLDABSOLUTE PRESSURESENSOR)
Detects MAP sensor signalWith ignition switch ON (ll):about3 VAt idle: about 1.0 V (depending on enginespeed)
20YEUBLUVCC2 (SENSOR VOLTAGE)Provides sensor voltageWith ignition switch ON {ll): about 5 VWith ionition switch OFF: about0V21YEUREDVCC] (SENSOB VOLTAGE)Provides sensor voltageWith ignition switch ON {ll): about 5 VWith ionition switch OFF: about0V22AFSHTC - (AIR FUELRATIO (A"iFiSENSORHEATER CONTROL + SIDE)
Detects a,/F sensor heatervoltageWith ign;tion switch ON lll): banery voltage
23BRN?ryE LLG2 (LOGIC GROUNDround for the ECM circuLessthan 1.0 V at alltimes24BRN?ryE L1(Lround for the ECM circuLess than '1.0 V at alltimes25B LU,^/VHTCMP A (CAMSHAFT
POSITION SENSOR A)Detects CMP sensor AstonalWith engine running: pulses
26GRNCMP B CAMSHAFTPOSITION (CMP)SENSOBB (TDC (TOP DEAD CENTERSENSORi)
Detects CMP sensor 8 (TDc
sensor)With engine running: pulses
27BRNIGPLS4 {No. 4IGNITIONCOIL PULSE)Drives No, 4 ignition coiWith ignition switch ON (ll)r about 0 vWith engine running: pulses28WHT/BLUIGPLS3 {No.3IGNITIONCOIL PULSE)Orives No.3 rgnition coi
29BLU/REDlGPLS2lNo.2 IGNITIONCOIL PTJLSE)Drives No.2 ignition coil
30YEUGRNIGPLSI (No. 1 IGNITIONco

PlltsF)Drives No. I ignition coil
11-20
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a
a

Wire side o{ female terminals
NOTE: Standard baftery voltage is 12 V.
Terminalnumo€tWire color[erminal nameDescriptionSignal
BLUAvHTVTC+ lVTC OIL CONTBOLSOLENOID VALVE +SIDE)Drives VTC oilcontrolWith ignition switch ON (ll): 0 V
2lNJa {No. 4INJECTOR)Driveso. 4 iniectorAt idle: duty controlled
3BLJo.3INJECTORIDriveso.3 iniector4R1)TOR)Driveso.2 iniector
5BRNlNJl 1No. I INJECTOR)Drives No. 1 iniector
6GRNFANC (RAOIATOR FANCONTROL)Drives radiator fan relayWith radiator fan running: about 0 VWith radiator fan stopped: batterv voltaoe
7GRN/vVHTRVS (REVERSE LOCKSOLENOID VALVE)Drives reverse lock solenoidWith vehicle speed below 9.4 mph (15 km/h):battery voltageWith vehicle speed above 12.5 mph (20 km/h): 0 V
8REDAVHTECT (ENGINE COOLANTTFMPFRATURE SENSOR)Detects ECT sensor signalWith the ignition switch ON (ll): about 0.1 4.8 Videoendino on enoine coolant temDerature)
9BLU/BLKVTPSW (VTEC OILPRFSSTIRF SWITCH)Detects VTEc oil pressureswitch sionalWith engine at low engine speed: about 0 .Wirh enoine at hioh enoine soeed: batterv voltaqe
10WHT/BLUALTL (ALTEBNATOR LSIGNAI IDetects alternator L signalWith ignition swit'ch ON (ll): about 0 VWhh enoine runnino: batterv voltaqe
WHT/REDALTF (ALTERNATOR FRSIG NALIDetecls alternator FB signalWith engine running: about 0 V- 5 V{deoendinq on electrical load)
GRN/YELVTS {VTEC SOLENOIDDrives VIEC solenoid valveAt idle: about 0 V
'17REDI/ELIAT (INTAKE AIRTEMPERATURE SENSOR)Detects IAT sensor signalWith ignition switch ON {ll): about 0.1 V 4.8 vl.lcnen.iino on intake air temoerature)
18WHT/GRNALTC (ALTERNATOR
CONTROL)Sends alternator controlWith engine running: about 0 V 5 V(.lcocn.lino on electrical ioad)
21YEUBLUPCS {EVAPORATIVEEMISSION CANISTERPURGE VALVE)
Drives EVAPcanister purgevalveWith engine running, engine coolant below 149'F
165'C): battery voltageWith engine running, engine coolant above 149'F165"C): dutv controlled
23BLK/Vr'HTVTC (VTC OIL CONTROLSOI FNOID VALVE SIDE)Drives VTC oilcontrolWith the ignition switch ON (ll): 0 V
(confd)
11-21