1998 HONDA CIVIC main fi

ldle Gontrol System
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the
ECM/PCM in order to maintain the proper idle speed.BIMETALHOLDER
BIMETAL
SHAFTVALVESTOPPER
ECM/PCM CONNECTOR B {25P}
(To page 11-201)
IAC VALVE 3P CONNECTOR
IACV NIACV P
ldle Air Control {lACl Valve ('99 - 00 A/T and Dl6Y7 enginel
YES
1P1509 lThescantool indicates Diagnostic Trouble Code (DTC) P1509:A problem inthe idleAirControl (lAC)valve circuit.
IGP
Terminal side of maleterminals
Sub3titute e known-good ECM/PCM .nd recheck. lf 3vmptom/indicalion goos away, replac6thc original ECM/PCM.
*: IACV N line
11-200
Tho MIL has b€en reported on.OTC P1509 is sto.ed.
Problem verilicationr1. Do the ECM/PCM Reset Proce-dure.2. Turn the ignition switch ON (ll).
Intermittont tailure, sy3tem i3 OKat thb time. Check for poor con'noctions or loose wiros at C109(lAC velvel and ECM/PCM.
ls DTC P1509 indicated?
Check for an oDen in the wilosIPG linesl:Measure voltage between bodyground and ECM/PCM connectorterminals 82 and 810 individually.
Ropail open in the wires be'tw€enECM/PCM .nd G101 llocated .tthe the.mostat housingl.ls there more than 1.0 V?
Check tho ECM/PCM input volt-age:1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)trom the ECM/PCM.3. Turn the ignition switch ON (ll).
4, Measure voltage betweenbody ground and ECM/PCMconnector terminals 86 and815* individually.
Chock the IAC v.lve:1. Turn the ignition sw;tch OFF.2. Disconnect the IAC valve 3Pconnoctor.3. Measure resistance betweenIAC valve 3P connector termi'nal No. 2 and terminals No. 1and 3 individually.
ls there 16 - 28 O?
Wire side of female terminals

I
I
L
IACV N(oRN)*IACV P{BLK/BLU'
ECM/PCMCONNECTON B (25PI
IACV N(oRNt.
Wire side of female terminals
IAC VALVE 3P CONNECTOR
IACV NIACV P
IACV P
IBLK/BLUI
IGP
Terminal side of male
(From page 11 200)
IAC VALVE 3P CONNECTOR {C1O9I
IGP (YEL/BLK)
Wire side of female terminals
Check toi an open in thg wire
{lGP line):1. Turn the ignition switch OFF.
2. Disconnect the IAC valve 3P
connector.3. Turn the ignition switch ON (ll)
4, At the wire harness, measure
voltage between IAC valve 3P
connector terminal No. 2 and
body gro!nd.
Repair open in the wire between
the IAC valve and PGM-FI main
reraY.
Check for an open in the wires
IIACV P. IACV N' lines):
1. Turn the ignition switch OFF.
2. Disconnect the ECM/PCM con-
nector A (32P).
3. Check lor continuity between
IAC valve 3P connector termi'nal No. 3 and ECM/PCM con-necto r terminal B6 (and
beNveen IAC valve 3P connector terminal No. 1 and ECM/PCM connector terminal 815)*.
Repair open in the wiro ltstwcen
the IAC valvo and €CM/PCM (86,
815'1.
Check for a shon in the wires(IACV P, lACv N* linesl:Check for continuity between
body ground and ECM/PCM con-
nector terminals 86 and 815*
individually.
Reoair short in the wiro Mweonthe lac valve end ECM/FCM (86,
815*).ls there continuity?
Check the IAC valv€:l. Disconnect the IAC Valve 3P
connector,2. Measure resislance betweenIAC Valve 3P connector termi
nal No. 2 and terminals No 1and No.3 individually
ls there 16 - 28 O?
Substituta . known-good ECM/
PCM and rochcdc f 3ymptom/indication go€a away, r€dace the original ECM/Pqvl.
"r IACV N line
N
11-201

ldle Control System
Starter Switch Signal ('96 - 98 Models,'99 - 00 D16Y5 engine with M/Tl
Thjs signals the ECM/PCM when the engine is cranking.
NOTE:. A/T: Transmission in E or E position. M/T: in neutral
a l32PlLGl
Wire side ot female lerminals
Check tor an open or short in thewire ISTS linel:Measure voltage between ECM/PCM connector terminals A9 andC6 with the ignition switch in thestart lllli position.
Inspect the No. 31 STARTER SIG-NAL (7.5 A) fuse in the underdashfuse/relay box.
- Repair .hort in the wirebotwoen tha ECM {C6l andtho No, 31 STARTER SIGNAL{7.5 Al tuss or the PGM-FImain relay,- Roolac. the No. 3'l STARTERSIGNAL l?.5 Al tu3€.
Staner 3witch signal is OK.
Repair opon in th6 wiro botweanih. ECII4/PCM (C6) and the No.31STARTER SIGNAL {7.5 Al tulo.
ECM/PCM CONNECTORS
{BRN/BLKISTS IBLU/ORNI
216910It3567a9l0
l2l3la15!6171a1920222att12t3l4t5t6171E
252l2A7t30232a2930
11-202

Fuel Supply System
System Description
The fuel supply system consists of a fuel tank, in-tank
high pressure fuel pump, PGM-FI main relay, fuelfilter,
fuel pressure regulator, fuel injectors. and fuel delivery
and return lines. This system delivers pressure-regu-
lated fuel to the fuel injectors and cuts the fuel delivery
when the engine is not running.
Fuel Pressure l'96 Modelsl
Relieving
Before disconnecting fuel pipes or hoses, release pres-
sure from the system by loosening the 6 mm service
bolt on top of the fuel filter.
. Do not smoke whil6 working on the fuel system.
Kgsp opon flames or sparks away from youl work
area.
. Be sure to relieve fuel pressure while the ignition
switch is off.
1. Write down the frequencies for the radio's preset
buttons.
2. Disconnect the battery negative cable from the bat-
tery negative terminal.
3. Remove the fuelfill cap,
4. Use a box end wrench on the 6 mm service bolt at
the fuel filter while holding the special banjo bolt
with another wrench,
5. Place a rag or shop towel over the 6 mm service bolt.
6, Slowly loosen the 6 mm service bolt one complete
rurn.
. A fuel pressure gauge can be attached at the 6 mm
service bolt hole.
. Always reDlace the washer between the service
bolt and the special banjo bolt whenever the ser-
vice bolt is loosened.
. Replace all washers whenever the bolts are
removeo.
11-230
Inspoction
1. Relieve fuel pressure.
2. Remove the service bolt on the fuel filter while hold-
ing the banjo bolt with another wrench. Attach the
special tool.
FUELPRESSUREGAUGE07406 - 00ir0(x)1
Start the engine. Measure the fuel pressure with the
engine idling and the vacuum hose of the fuel pres-
sure regulator disconnected from the fuel pressure
regulator and pinched. lf the engine will not start,
turn the ignition switch ON (ll), wait for two sec-
onds, turn it off, then back on again and read the
fuel pressure.
Pr€3sure should bo:
260 - 310 kPa (2.7 - 3.2 kgt/cmr, 38 - 46 psi)
Reconnect vacuum hose to the fuel pressure regulator,
Pressure should bo:
200 - 25O kPa l2.O - 2.5 kgf/cm', 28 - 36 psil
lf the fuel pressure is not as specified, first check the
fuel pump {see page 11-2361. lf the fuel pump is OK,
check the following:
. lf the fuel pressure is higher than specified,
inspect for;- Pinched or clogged fuel return hose or line.- Faulty fuel pressure regulator (see page 11-234).. lf the fuel pressure is lower than specified, inspect
for:- Clogged fuelfilter.- Faulty fuel pressure regulator {see page 11-234).- Fuel line leakage.
REGULATOB

Fuel Supply System
Fuel Pump
Testing
!@ Do not smoke during the test, Keep open
flame away from your work atea,
lf you suspect a problem with the fuel pump, check that the
fuel pump actually runs; when it is ON (ll), you will hear
some noise if you hold your ear to the fuel fill port with the
fuel fill cap removed. The fuel pump should run for two
seconds when ignition switch is first turned ON (ll). lf the
fuel pump does not make noise, check it as follows:
L Remove the seat cushion {see section 20).
2. Remove the access panel from the floor.
3. Make sure the ignition switch is OFF, then discon-
nect the Iueltank 2P connector.
4. Connect the PGM-FI main relay 7P connector termi-
nal No. 4 and No. 5 with a jumper wire.
PGM-R MAIN RELAY 7P CONNECTOR lC4,(|l
FUEL PUMP
IYEL/GRN}
IGN 1(YEL/GRNI
tcs6s)
FUEL PUMP(YEL/GRNI
Wire side oftemale torminals
JUMPER WIRE
Wire side of temale terminals
Check that battery voltage is available between the
fuel pump connector terminal No. 1 and body ground
when the ignition switch is turned ON (ll).
CONNECTOR
=
[t
L3l .i)
T
lf battery voltage is available, check the fuel pump
ground. lf the ground is OK, replace the fuel pump.
lf there is no voltage, check the wire harness (see
page 11-238).
11-236
Replacement
@E Do not smoke while working on tuel svs-
tem. Keep open llames away from your work area.
1. Remove the seat cushion (see section 20).
2. Remove the access panel trom the floor.
3. Disconnect the 2P connector from the fuel pump.
4. Remove the fuel pump mounting nuts.
5. Remove the fuel pump from the fuel tank.
6. Install pans in the reverse order of removal.
ACCESS PANEL
i

I
PGM-FlMain Relay
Description
The PGM-Fl main relav actuallv contains two individual
relays. This relay is located at the right side of the cowl.
One relay is energized whenever the ignition is on which
supplies the battery voltage to the ECM/PCM, power to
the luel iniectors, and power for the second relay. The
second relay is energized lor two seconds when the igni-
tion is switched ON (lll, and when the engine is running,
to supply power to the luel pump.
PGM-FIMAIN RELAY
J
I
t
FUEL PUMP
Relay Testing
NOTE:
. It the engine starts and continues lo run. the PGM Fl
main relay is OK.
. Use the terminal numbers below;
ignore the terminal numbers molded into the relay,
1. Remove the PGM Fl main relay.
2. Attach the battery positive terminal to the No. 2 ter-
minal and the battery negative terminal to the No 1
terminal of the PGM-Fl main relay. Then check for
continuity between the No.5 terminal and No 4ter-
minal of the PGM Fl main relay.
. lf there is continuity, go on to step 3.
. lf there is nocontinuity, replacethe PGM-Fl main
relay and retest.No. 3No. 1
To lGN. 1
To GROUND
To ST. SWITCH
To ECM/PCM {A161
To 8AT O
To ECM/PCM{(a11, A241, (81. B9l*l
To FUEL PUMP.r '99 model
3.Altach the batterv positive terminal to the No.5 ter-
minal and the battery negative terminal to the No. 3
terminal of the PGM-Fl main relay. Then check that
there is continuity between the No. 7 terminal and
No. 6 terminal of the PGM-Fl main relay.
. lf there is continuity, go on to step 4
. lf there is nocontinuity, replacethePGM-Fl main
relay and retest.
Attach the battery positive terminal to the No. 6 ter-
minal and the battery negative terminal to the No. 1
terminal of the PGM Fl main relay. Then check that
there is continuity between the No. 5 terminal and
No. 4 terminal of the PGM-Fi main relay.
. lf there is continuity, the PGM-Fl main relay is OK.
lf the fuel pump still does not work, go to Harness
Testing on the next page.
. lf there is no continuity, replace the PGM Fl main
4.
(cont'd)
11-237
relay and retest.

Fuel Supply System
PGM-FI Main Relay (cont'dl
Circuit Troubleshootin g
PGM.FI MAIN RELAY 7P CONNECTOR {C443)
GND{8LK)
Wire side of female terminals
/BLK}
- Engine will not start.- lnsoection of PGM-FI mainrelay and relay harne$.
Check for an open in the wire{GNO line}:l. Turn the ignition switch OFF.2. Disconnect the PGM-Fl mainrelay 7P connector.3. Check for continuity betweenthe PGM Fl main relay 7P con-nector terminal No.3 and bodyground.
Ropai. open in the wir€ betweenthe PGM-FI main .elav and G101.
Check for an open or short in thewire {BAT lin€}:N4easure voltage between thePGM-FI main relay 7P connectorterminal No. 7 and body ground.- Repair open or sho.t in thewire between the PGM-FI mainrelay and the Fl E/M {15 A}fus€.- Replace the Fl E/M (15 Allu3ein the under-hood fuse/relayoox.
ls lhere battery voltage?
Check tor an open or short in thewire {lGl line):1. Turn the ignition switch ON (ll).
2. Measure the voltage betweenthe PGM-Fl main relay 7P con'nector terminal No. 5 and bodyground.- Repair open or short in thewire betwoen the PGM-FI mainrelav and the No. 13 FUELPUMP (15 A)tuse.- R€place the No. 13 FUELPUMP {15 A} tus€ in the under-d.sh fus€/relay box.
ls there battery voltage?
Ch.ck for an open or short in thewire {STS lino}r1. Turn the ignition switch to theSTART (lll) position.NOTE:. M/T: Clutch pedal must beoepresseo.. A/T: Transmission in E or
E position.2, Measure the voltage betweenthe PGM-Fl main relay 7Pconnector terminal No, 2 andbody ground.
12
[,a567
123BAT
{WHTa56,
'96 98 models: (To page 1l 239)'99 - 00 models: (To page I l-240)
11-238,

JI
I
- Repair open or 3hort in the
wire bstw€er the lGM-Fl mainrolsy .nd the No. 31 STARTERSGNAL 17.5 A) tuse.- Reolace the No. 31 STARTER
SIGNAL (7.5 Al fu3o in the
unde.-dash tusg/rolav box.
ls there baftery voltage?
Chock lor !n open in the wit.
lFLn line)l1. Turn the ignition switch OFF
2. Disconnect the ECM/PCM con-
nector A (32P).
3. Check for continuity between
the PGM-FI main relay 7P con-
nectorterminal No. 1 and ECM/
PCM connector terminal A16.
Ropair op6n in th. walo betwoanthe ECM/PCM lA16) and thc
PGM-FI main rolaY.
Ch6ck for an opon in th. wi.e3
llcPl,lGP2linesl:1. Reconnect the ECM/PCN4 con-nector A (32P).
2. Reconnoct the PGM-Fl main
relay connector,3. Turn the ignition switch ON (ll)
4. Measure voltage between
ECM/PCM connector termanals
A11 and A10, and betweenA24 6nd A10.
Repeir opon in th6 wire bet-
ween ttre ECiA /PCM (A11, A24)
and tho PGM-FI msin r.lty.
R€plac. tho FGM-FI main rc|.Y.
Check tor an open in the ECM/
PCM:1. Turn the ignition switch OFF.
2, Measure voltage between
ECM/PCM connector terminalsA16 and A10 when the ignition
switch is lirst turned ON (ll) for
two seconds.
Substituta a known-good ECM/
PCM and rechcck. lf proacribod
voltege is now availablc, r.Placethe originll ECM/PCM.
ls thero 1.0 V or less?
Ch6ck th. PGM-FI m.in lolay(.ee pagc 11-2371.
('96 - 98 models)
t32Pt
Wire side of female terminals
IGP2{YEL/BLKI
FLRIGRN/YELIPGl
3l5 6 7l lslel tl1l
1213'tal5t6't7t8t920221 232a
2527284t
(cont'd)
1 1-239
IBLK)
{GRN/YELI
FLR(GRN/YELI
23
()a6t
ECM/PCM CONNECTOR A
21Il0t1
12r31'al5't61'tti9ml,/x2232a
25212e293ol./
PGl (BLK)
1I
12't/t15t617t8t9zi
25272A4t304l