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Troubleshooting
ECM CONNECTOR {31P)
Engine Control Module Terminal Arrangement (cont'd)
ECM CONNECTOR C {31P)
235srsscs1112t31515t71A19
2A
Wire side of lemale terminals
NOTE: Standard battery voltage is 12 V.
TerminalnumbercolorTerminal namoD6scriptionSignal
1BLU/REDCKF P (CKF SENSOR P SIDE)Detects CKF sensor.With engine running: pulses
28LUCKP P (CKP SENSOR P SIDE)Detects CKP sensor.With engine running: pulses
3GRNTDC P {TDC SENSOR P SIDE)Detects TDC sensor,With engine running: pulses
YELCYP P (CYP SENSOR P SIDE)Detects CYP sensor,With engine running: pulses
5BLU/REDACS (AJC SWITCH SIGNAL)Detects A,/C switch signal.With A,/C switch ON: 0 VWith A,/C switch OFF: battery voltage
6BLUA/VHTSTS (STARTEB SWITCHSIGNAL)
Detects starter switch signal.With staner switch ON: battery voltageWith starter switch OFF: 0 V
7BRN,AiVHTSCS (SERVICE CHECKSIGNAL)Detects service check connectorsignal (the signalcausing a DTC;ndication).
With the co n nector con nected: 0 VWath the connector disconnected: about 5 V
8GRNAVHTK LINESends and receives OBD ll scantool and PGM tester signal.With ignition switch ON (ll): about 5 V
9YELFAS lFEEDBACK AT SIGNAL)Sends feedback signal for theTCM,At idle: about 5 VDuring shifting: momenlary change to 0 V
10WHT/BLU
VBU (VOLTAGE BACK UP)Power source for the ECMcontrolcircuit,Power source for the DTC
Battery voltage at all times
t1WHT/REDCKF M (CKF SENSOR I\4 SIDE)Ground for CKF sensor.
12BLUI/E LCKP M (CKP SENSOR M SIDE)Ground for CKP sensor.
WHT/BLUTDCM (TDC SENSOR M SIDE)Ground tor TDC sensor.
14CYPM (CYP SENSOR M SIDE)Ground for CYP sensor.
15*.BLU/BLKVTP SW (VTEC
PRESSUFE SWITCH)Detects VTEC pressure switchsr9nal.
With engine at low rpm:0 VWith engine at high rpmlbattery voltaqe
161,GRN
PSPSW (P/S OILPRESSURE SWITCH)Derecls PSP switch signal.At idle with steering wheel in straight aheadpositioni 0 VAt idle with steering wheelat full lock: batteryvoltage
17WHT/REDALTF (ALTERNATOR FRSIGNAL)Detects alternator FR signal.With fully warmed up engine running:0 V battery voltage (depending onelectrical load)
18ORNVSS (VEHICLE SPEEDSENSORiDetects VSS signal.With ignition switch ON (ll) and lrontwheels rotating: cycles 0 V- 5 V
19*3BLUAT CHK (A/T FI DATA LINE)Detects TCM data signal.With ignition switch ON (ll)i pulses
21*LT GRNBARO OUT (SAROMETRIC
SENSOR OUTPUT S!GNAL)Sends barometric sensor outputsrgnal,With ignition switch ON (ll): about 3 V(depending on barometric pressure)
27 x3GRYAFSB (A"/T FI SIGNAL B)Detects retard signal from theTCM,At idle: about 5 VDuring shifting: momentary changeto0V
28+1GRN/8LUA+SA (A/T FI SIGNAL A)Detects retard signal from theTCM.At idle: about 5 VDuring shifting: momentarV changeto0V
29+3LT GRN/BLKATPPN (A/T GEARPOSITION SWITCH)Detects A,/T gear position switchsrgnal-In E orE positionr 0VIn anv other position: battery voltage
*1: USA*2:818C1 engine*3: A/T*4: 818C1, 818C5 engines
ECM CONNECTOR D (16P}
Wire side of female terminals
ECM CONNECTOR D (16P1NOTE| Standard battery voltage is 12 V.
TerminalnumberWirecolorT6rminal nameDoscriptionSignal
1RED/BLKTPS (THROTTLE POSITIONSENSOR)Detects TP sensor s;gnal.With throttle fully open: about 4.5 VWith throttle fully closed: about 0.5 V
2REDAr'r'HTECT (ENGINE COOLANTTEMPERATUBE SENSOB}Detects ECT sensor signal.With ignition switch ON (ll)r about0.1 - 4.8 V (depending on engine coolanttemperalure)
3WHT//ELMAP {MANIFOLD AESOLUTEPBESSURE SENSOR)Detects MAP sensor signal.With ignition switch ON (ll)iabout 3 VAt idle: about 1.0 V {depending on enginespeeol
4YELA/VHTvccl{SENSOR VOLTAGE)Power source for MAP sensor,With ignition switch ON (ll): about 5 V
5GRNAVHTBKSW (BRAKE SWITCH)Detects brake switch signal.With brake pedal released: 0 VWith brake pedal depressed: batteryvoltage
6*!RED/BLUKS (KNOCK SENSOR}Detects KS signal.With engine running: pulses
lPHO2S (PRIMARY HEATEDOXYGEN GENSOR)Detects primary oxygen sensorsignal.With throttle fully opened, fully warmed upengine: above 0.6 VWith throttle quickly closed: below 0.4 V
8RED/VEL
IAT (INTAKE AIRTEMPERATURE SENSOR)Detects IAT sensor signal.With ignition switch ON {ll): about0.1 - 4.8 V (depending on intake airtemperature)
10YEL/BLUvcc2(SENSOB VOLTAGE)Provides sensor voltage,With ignition switch ON (ll): about 5 VWith ignition switch OFF: 0 V
1lGRN/8LUSG2 (SENSOR GROUND}Sensor ground.Less than 1.0 V at all times.
GFNA/VHT(SENSOR GROUND}Ground tor MAP sensor.Less than 1.0 V at all times.
OBN/BLUSHO2S GND (SECONDARY
HEATED OXYGEN SENSORGROUND)
Ground for secondary heatedoxygen sensor,Less than 1.0 V at alltimes.
148LU/REDSH02S (SECONDARY
HEATED OXYGEN SENSOR}Detects secondary oxygensensor srgnal.With throttle fully opened. fully warmed upengine: above 0,6 VWith throttle quickly closed: below 0.4 V
LT GRNPTANK (FUEL TANK PRESSURE SENSOR)Detects fueltank pressure sensor.With luel fill cap opened: about 2-5 V
GRN/RED
EL (ELOiDetects ELD signal.With parking lights turned on at idle: about2.5 -3.5 VWith low beam headlights turned on at idle:about 1.5 - 2.5 V*1:USA*2: 818C1 engine"3:A"/T*4: B18C'1, 818C5 engines
11-41
PGM-FI System
System Description
ENGINE CONTROL MODULE (ECM)OUTPUTS
*1: USA*2: 818C1 engine*3: A,/T*4: 818C1, 818C5 engines
PGM-FI Sy3tem
The PGM-Fl system on this model is a sequential multiport fuel injection system.
Fuel lniector Timing and Duration
The ECM contains memories for the basic discharge durations at various engine speeds and manifold pressures. 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 Ai. Control Valve (lAC Valve)
When the engine is cold, the Ay'C compressor is on. the transmission is in gear (Ay'T only)the brake pedal is depressed, the
P/S load is high, or the alternator is charging, the ECM controls current to the IAC Valve to maintain correct idle speed.
lgnition Timing Control
. The ECM contains memories for basic ignition timing atvarious engine speeds and manifold pressures, lgnitiontiming
is also adjusted for engine coolant temperature.
. AKnockControl System isadoptedwhich sets the ideal ignition timing for the octane n um ber of gasoline used*r,
Other Control Functions
L Starting Control
When the engine is started, the ECM provides a rich mi{ure by increasing fuel injector duration.
2. Fuel PumD Control
. When the ignition switch is initially turned on, the ECM supplies 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 supplies ground to the PGM-FI main relay that supplies current to the fuel
DUmO.
. When the engine is not running and the ignition is on. the ECM cuts ground to the PGM-FI main relay which cuts
current to the fuel oumo.
INPUTS
TDc/CKP/CYP Sensor
CKF Sensor
MAP Sensor
ECT Sensor
IAT Sensor
TP Sensor
HO2S
VSS
BARO Sensor
ELD*1
Starter Signal
ALT FR Signal
Air Conditioning Signal
A,/T Gear Position Signal*3
Battery Voltage (lGN.1)
Brake Switch Signal
PSP Switch Signal*'
Knock Sensor*1
VTEC Pressure Switch*4
Fuel Tank Prssure Sensor
Fuel InjectorTiming and Duration
Electronic ldle Control
Other Control Functions
lgnition Timing Control
ECM Back-uD Functions
Fuel-lnjectors
PGM-Fl Main Relay (Fuel Pump)
MIL
IAC Valve
A,/C Compressor Clutch Relay
Radiator Fan Belay*1
Condenser Fan Relay
ALT*1
rcM
EVAP Purge Control Solenoid
Valve
H02S Heater
VTEC Solenoid Valve*'
IAB Control Solenoid Valve*,
EVAP Bypass Solenoid Valve
EVAP Control Canister Vent
Shut Valve
11-48
3.Fuel Cut-off Control
. Du ring dece leration with the th rottle va lve closed, cu rrent to the fuel injectors is cutoffto improvefuel economyat
speeds over following rpm:. B'1881 engine: 970 rpm {Canada model: 1.050 rpm). B18C1 engine:970 rpm {Canada model: 1.050 rpm). 818C5 engine: 1,300 rpm (Canada model: 1,400 rpm)
. Fuel cut-off action also takes place when engine speed exceeds 7,000 rpm (B'1881 engine), 8.100 rpm (818C1
engine) or 8,600 rpm (818C5 engine), regardless ol the position of the thronle valve, to protect the engine from
over-revving.
A,,/C ComDressor Clutch Relav
When the ECM 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 coolanl temperature is above '154'F (68'C) and the air conditioner on. the ECM controls the EVAPpurge control solenoid valve which controls vacuum to the EVAP purge control canister.
Intake Air Eypass (lAB) Control Solenoid Valve*a
When the engine rpm is below 5,750 rpm, rhe IAB control solenoid valve is activated by a signal from the ECM, intake
air flows through the long intake path, then high torque is delivered. At speeds higher than 5,750 rpm, the solenoidvalve is deactivated by the ECM, and intake air flows through the short intake path in order to reduce the resistance in
airflow.
Sell-diagnosis Function lMalfunction Indicator Lamp {MlL)lWhen an abnormality occurs in a signal from a sensor, the ECM supplies ground for the MIL and stores the code in
erasable memory. When the ignition is initially turned on, the ECM supplies ground for the N4lL tor two seconds to
check the MIL bulb condition.
Two Driving Cycle Detection Method
To prevent false indications, the Two Driving Cycle Detection Method is used for the HO2S, fuel metering-related, idle
control system, ECT sensor, TWC and EVAP control system and other self-diagnostic functions, When an abnormality
occurs, the ECM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFFand ON (ll)again, the ECM informs the driver by lighting the MlL.
However, to ease troubleshooting, this function is cancelled when you shon the service check connector. The MIL will
then blink immediately when an abnormality occurs.
4.
5.
6.
3.
4.
ECM Fail-safe/8ack.up F0nctions
1. Fail-sate Function
When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed
value for that sensor that allows the enqine to continue to run.
2. Back-uo Function
When an abnormality occurs in the ECM itself, the fuel injectors are controlled by a back-up circuit independent of the
system in order to permit minimal driving.
11-49
I
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PGM-FI System
Engine Control Module {ECMI
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{
ili
NOTE: lf this svmotom is intermittent, check for a loose fuse No. 25 METER (7.5A) in the under_
dash fuse/relay box, a ooor connection at ECM terminal A18, or an intermittent open in the
GRN/ORN wire between the ECM (A18) and the gauge assembly.
Wire side of female terminals
I
The Mellunction Indicator Lamp(MlLl never com€3 on leven foltwo secondsl alter ignition islurn6d ON lll).
Turn the ignition switch ON (lli.
- Repair short or open in th€wire betwe€n No. 25 METER{7.5 A}fuse and gauge assem-bty.- ReDlaco No.25 METER 17.5 A)fuse.
ls the low oil pressure light on?
Try to start the engine,
Check for an open in ih6 wires
IPG lines):1. Turnthe ignition switch ON (ll).
2. Measure voltage betweenbody ground and ECM connec-tor terminals A10 and A23 indi-vidually.
Chock for an open in the wire orbulb:1. Turn the ignition sw;tch OFF.2. Connectthe ECM connector terminal 418 to body ground with
3. Turn the ignition switch ON (ll).
Repair open in the wire(slbetween ECM and G101 (located
at thermostat housingl that hadmore than 1.0 V.
ls there less than 1.0 V?
Substitute . known-good ECMand .echeck, lf symptom/indica-tion goes away, replace the origi-nalECM.
- R€pair open in the wiresb€tweon ECM {A18land gaug€
ess€mbly.- Replace the MIL bulb.
ls the MIL on?
Substitute a known-9ood ECMand rech6ck. It symptom/indica-tion goes away, repbce the origi-nal ECM.
ECM CONNECTOR A {32P)
15 16 17 18 19
r 2 3 al 15 Ga910 11
12 ,, t5 16 1tt920/22 23 2a
25 26 211184tt-MILJUMPER(GRN/ORN) I WIRE
NOTE:. Whon there is no cod6 stored, the MIL willstay on iftho aorvice check conn€ctor is snoned.' lfthis symptom is intermittent. check tor:- A loos6 Fl E/M (15 A) in the undor-hood tuse/relav box- A loose No. 13 FUEL PUMP {SRS UNIT) (15 A) in th6 under-dash fuse/retay box- An intermitt6nt short in the wir€ betwesn the ECM (C7) and th€ sorvice chock conn€qor- An intormittent open in the wire between the sorvice chsck conneclor and G40l- An intermittent short in the wire betwo€n the ECM (A18) and the gaug6 assemDry- An intermittent shon in the wir6 between the ECM (D14) and the MAP sonsor- An intermittent shon in the wire bstween the ECM (Dto), th6 Tp sensor and Fu6l tankpI6SSU16 SOnSOT- PGM-FI Main relay. See th6 OBD ll scan tool or Honda PGM Tester user's manuals for sp6cific operating instruc-!ons.
(To page 11-52)
(cont'd)
Th. M.lfunction Indic.tor LlmplMlll .t!yr on or comlr on ltt .two aaconda.
Ch.ck th! Dirgnoitic tioubl.Cod. IDTC):'1. Connoct a 6can tool or HondaPGM Tester,2. Turn tho ignition switch ON (ll).3. Read tho DTC with the scantool or Honda PGM T6st6r.
Go to trouHorhooting proQduaaa.
koo p.g6 I 1.3:ll
Ch.ct th. DTC by MIL indication:1. Turn th€ ignition switch OFF.2. Connect the SCS seNic€ con-n€ctor to the sorvico checkconnoctor,3. Turn the ignition s1\,itch ON (ll).
Rapair opan or ahort in wirabotw..n thg ECM lCSl .ndData Llnk Conncctor.Go lo troublcrhootlng pro-c.dur.3. {.co pag. 11-32)
Do.s th6 MIL indicate anv DTC?
Try to start tho engine.
Chack lor r 3hort in th. wlr.3lsqg lln.):1. Turn the ignition switch OFFand turn the ignition switchoN { },2. Disconnect th6 SCS serviceconnector,3. M€a6urg voltaOe between theECM connoctor torminal C7and body ground.
Rapah 3hort to body ground inlh. wir. b.lw..n ECM lCTl .ndacwica chack connactor.
ls ther6 approx. 5 V?
\{,
(To page 11-52)
11-51
PGM.FISystem
Gontrol Module (ECMI (cont'dlEngine
\
L
(From page 11-51)
Choc* tol s short in tho wir6 lMlLlino):1. Turn the ignition switch OFF.2. Disconn€ct the ECM conn6c-tor A (32P).
3. Turn the ignition switch ON (ll).
Repair 3hon to body ground in
rhe wire bstw.on tho ECM (A181
and MlL.
Substituto s known-good ECMend rechock. H 3ymptom/indica-tion goes awry, replacc tho origi-nelECM,
{From page 11-51)
Inspect Fl E/M (15 A) fuse in theunder-hood Iuse/relay box.
- Ropsir short in tha wircbotw.on Fl E/M {'15 Al tu3c'rnd PGM-FI m.in t.lry.- Rool.c. Fl E/M l15A)tu!€.
Inspect No. 13 FUEL PUMP (SRS
UNIT) ('l5A) fuse in the undeFdash fuse/relay box.
- Reo.ir sholt in th. wirobotw..n No. 13 FUEL PUMP
{SRs UNIT) (15 Al fur..ndFGM-FI m.in rclay.- Repl.co No. 13 FUEL PUMP(SRS UNIT) {15 Alturr.
Ch6ck for . shon in a son3or1. Turn the ignition switch ON (ll).
2. Disconnect the 3P connectorfrom oach sensor one at time:. MAP sensor. TP sensor. Fueltank pressure sensor
Rapl.cc tha 3onaor thrt cauaadihe light to 9o out.Does the MIL go OFF?
1-52
(To page 11-53)
{From page 11 52)
Chock lor a shon in lhe wi.asiVCC1. VCC2lin$l:1. Turn the ignition switch OFF-2. Disconnect the ECM connec,tor D (16P).
3. Check lor continuity betweenbody ground and ECM con-nector terminals D4 and D10individually.
- Repair short to body groundin tho wire between ECM {D4land MAP 3enso..- Rep.ir short to body groundin the wire between ECMlD10l, TP sensor and Fueltank pa6ssure sanso..
Chock lor an op€n in the wire3{lGP1.lGP2lines):1. Turn the ignition switch ON (ll).2, Measure voltage betweenbody ground and ECM connec-torterminals A'11 and A24 indi-vadually.- R6pe;r open in the wire{slbetween ECM 1A11, A24l andPGM-FI main .elay.- Check for poor connectionsor loose wi.es at the PGM-FImain relay.- Test tho PGM-FI main ral.v(see page 11-124).Check for an open in the wires(LG1, LG2line3l:1. Reconnect all sensor connec-tors.2. Reconnect the ECM connectorD (16P).
3. Turn the ignition switch ON (ll).4- M easu re voltage betweenbody ground and ECM connector terminals A9 and A22individually.
Repai. open in the wir€ls)bctween ECM {A9, A22l .ndG101 ihet had more then 1.0 V.
ls there lessthan 1.0 V?
Substitute , known-good ECMand rechock. f symptom/indica-tion goes away, roplac6 the odgi-n3l ECM.
Wire side of female terminals
ECM CONNECTOR A I32P)
a,
Wire side of female terminals
LGl
1 1-53