Iac HONDA CIVIC 1997 6.G Service Manual

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{From page 11-196)
Repair opon or short in lhe wire
between EcM lBzl) and lAc valve.ls there battery voltage?
Check the IAC valve fundion:Momentarily connect ECM con-
nector terminals 823 and 82 with
a iumpe. wire several tames.
Does the IAC valve click?
Substitute a known-good ECM
and rocheck. ll symptom/indicd-tion go€s away, rePlace tho origi_
nal ECM.
Wire side of female terminals
11-197

ldle Control System
ldle Air Control (lAC) Valve ('96 - 98 A/T and Dl6Y7 enginel
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from theECM/PCM in order to maintain the proper idle speed,
BIMETAL
VALVESTOPPER
1P1509 Thescantool indicates Diagnostic Trouble Code (DTC) P1509: A problem in the idle Air Control (tAC)valve circuit.
ECM/PCM CONNECTOR A I32PIPGl IBLKI
IAC VALVE 3P CONNECIOR
IACV NIACV P
IGP
Terminal side of maleterminals
*: IACV N line
1 1-198
The MIL has b€€n roported on.DTC P1509 is stored.
Problem verification:1. Do the ECM/PCM Reset Proce-oure.2. Turn the ignition switch ON (ll).
Intermittent failura, systom ia OKat this time. Check tor poo. con-noctions or loose wires at C109llAC valve) and ECM/PCM.
ls DTC P1509 indicated?
Check for an opon in the wirer{PG lines):Measure voltage between bodvground and ECM/PCII connectorterminals A10 and A23 individu
Repair op€n in the wires betwoenECM/PCM and G101 llocated attho thermostat housing).
ls there more than 1.0 V?
Chock th€ ECM/PCM inpui volt-agel1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)from the ECM/PCM.3. Turn the ignition switch ON (ll).4. Measu re voltage betweenbody ground and ECM/PCMconnector terminals A14 andA13* individually.
Ch6ck th6 IAC valve:1. Turn the ignition switch OFF.2. Disconnect the IAC valve 3Pconnector,3, Measure resistance betweenIAC valve 3P connector termi-nal No.2 and terminals No. 1and 3 individually.
ls there 16 - 28 g?
Substitute a known-good ECM/PCM and recheck. lf symptom/indication goos away, replaceth€ origin.l ECM/PCM.
SHAFT
rAcv N loRNl*
(To page 11-199)
Wire side of lemale terminals
123a56El011
121314r5161718t9202:22321
272AA30
IACV P {BLK/BLUI

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lFrom page 11-198)
Chock for an opon in tho wilo(lGP lins):'1. Turn the ignition switch OFF.
2. Disconnect the IAC valve 3P
connector,3. Turn the ignition switch ON (ll),
4. At the wire hamess, measure
voltage between IAC valve 3P
connector terminal No. 2 and
body ground.
Raprir op€n in th€ wirc botw.€nth. IAC vrlv6 and PGM.FI mtin
rehy.ls there baftery voltage?
Check for rn open in tho wil.s(IACV P,IACV Nr linesl:
1. Turn the ignition switch OFF.
2. Disconnect the ECM/rcM con-
necror A (32P).
3. Check for continuity betweenIAC valve 3P connecto. terma_nal No. 3 and ECM/PCM con-nector terminal A14 (a nd
between IAC valve 3P connec-tor terminal No. 1 and ECM/
rcM connector terminal A13l*.
Ropair opan in tha wito bgtwoon
ths IAC vrlv! rnd ECM or PCM
{A14, 413.1.
Check for e lhort in tho wiros(IACV e nCV Nr linc):
Check for continuity between
body ground and ECM/PCM con-
nector terminals A14 and A13*
individually.
Rapair rhort in thr wi]. batwaonth. IAC v.lvc .nd ECM/PCfvl {A14,Ar3.t.ls there continuity?
Check the IAC V.lvo:1. Disconnect the IAC Valve 3P
3. Measure resistance betweenIAC Valve 3P connector termi-
nai No. 2 and terminals No. 1
and No. 3 individuallY.
ls there 16 - 28 O?
Subrtituto a known-good ECM/PCM and r€ch€d( lt .vmptom/indicalioo gp€. .way, ruplace tho odgiml Eqvt/FCM.
IAC VALVE 3P CONNECTOR IClG'}
IGP IYEL/BIX)
tAcv N (oRNt*
IACV N
Wirc side of lemale teaminals
IAC VALVE 3P CONNECTOR
IACV P
Terminal side of mal6tetmtnats
(32P)
ll
toRNt*tIIACV P(BLK/8LU}
ECM/PCMCONNECIOR A
IACV P(BLK/BLU}
Io,tl0't1
1Z13ta15l617tal9mx22321
2521i6a3o
,|31.57aIl0tl
12t3r. lrst511r8t92022232a
272aA30
IACV P (BLK/SLU}
rla
-: IACV N line
1 1-199

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

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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 Gontrol System
Air Gonditioning Signal ('96 - 98 Models, '99 - 00 Dl6Y5 engine with M/Tl
a {32P1ECM/PCM CONNECTORS
Wire side of female terminals
c l3lPl
This sjgnals the ECM/PCM when there is a demand for cooling from the air conditioning system.
(To page 11-205)
Check for a short in the wire{ACS line):1. Turn the ignition switch OFF.2. Disconnect the A/C pressure
switch 2P connector {see section 22).3. Turn the ignition switch ON (ll).
4. Measure vo lta ge betweenECM/PCM connector termi-nals C5 and A9.
Check for a .hort in the wi.e {ACSline):1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector C (3lPi.
3. Check tor continuity betweenbody ground and ECM/PCMconnector terminal C5,
ls there approx. 5 V?
Reotir short in the wi.e betweenthe ECM/PCM lc5l and rhe A/Cpressure switch.
ls there continuity?
- Substitute a known-goodECM/rcM .nd re.fieck. f Dre-scribed voltage is now availtble, replace the original ECft4/PCM,- See the air conditioner inspe-tion ls€e s€ction 221.
Check tor an op€n in the wireIACC lin6l:1. Turn the ignition switch OFF.2. Reconnect the A/C pressure
switch 2P connector.3. Turn the ignition switch ON (ll).
4. Momentarily connect ECM/PCM connector terminals A9and A17 with a jumper wire
LGl IBRN/8LKIACS {BLU/RED)
2361I9't0Itt3a89t0
12't31al5l617t8t920232all12l3l!ai5!617'tE
252l2A2930232a252930
ACS (BLU/BEDI
LGl IBRN/BLKI
123aslslrl lolgl ro lrr I
121314l516y)nltslnl/@) zr I zr I
25271!M1 1-/r
ACC
11-204
IBLK/RED)JUMPER WIRE

(From page 11-204)
Check for an open in the wir€(ACC linel:Momentarily connect underhood
fuse/relay box 9P connector teF
minal No. 5 to body ground with
a iumper wire several times.
ls there a clicking noise from
the IVC compressor clutch?
See air conditionor inspection(see 3oction 221.ls there a clicking noise from
the Py'C compressor clutch?
Repair open in the wire between
rhe ECM/PCM lAl7l and th6
under-hood fu3e/rolaY box 9P
connector lC352l.
Check for the oPeration of the
Alcl1. Start the engine.2. Turn the blower switch ON
3. Turn the AJC switch ON.
Chock tor an open in the wire
IACS linel:Measure voltage between ECM/
PCM connector terminals A9 and
c5.
Does the Ay'C operate?
Air conditioning signal is OK.Repair open in the wire b€tweenthe EcM/PcM lC5) and the A/c
3witch.ls there less than 1.0 V?
- Substiiute a known-goodECM/PCM and recheck ll
symptom/indication 9oesaway, .oplace the originalECM/PCM.- See the air condhioner insP€c_tion {see s€c{ion 22).
UNDER.HOOD FUSE/BELAYBOX 9P CONNECTOR 1C352)
12Ia
589
ACC (BLK/RI
Wire side ofACC (BLK/REDI
Wire side of female
terminals
JUMPERWIRE
ECM/PCM CONNECTORSrfA t32P)
LGlc {31Pl
t
(BRN/BLK)ACS IBLU/RED)
I23a9101t3I89t0
121315l611la1920232att12't3la't5t617ta
25272A2930232a2930
Wire side of lemale terminals

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JUMP€RWIRE
UNDER-HOOO FUSE/RELAYsox 9P coNNEcroR lca52l
123a
5689
ACC (8LK/REDI
Wire side ofterminals
ECM/PCM CONNECTORS
A (32P1
female
Wire side of {emale terminals
(From page 11-206)
Check for an open in the wite
IACC lino):Momentarily connect under_hood
luse/relay box 9P connector teF
minal No. 5 to body ground with
a jumper wire several times.
ls there a clicking noise from
the Iy'C compressor clutch?
S6e air conditioner insPoction
l3oa section 221ls there a clicking noise lrom
the ly'C compressor clutch?
Ropair open in tho wilo betwg€n
the ECM/PCM lA17) and the A/C
clutch rolay.
Chock for the oporation of lho
AIC:1, Start the engine.
2. Turn the blower switch ON
3. Turn the ray'C switch ON.
Check lor an open in the wiro(ACS lino):Measure voltage between ECM/
PCM connector terminals A27
and 820.
Does the Iy'C operate?
Air conditioning signal is OK.Repair op6n in the wiro bctwoon
lhe ECM/PCM lA27l and tho A/C
3witch.ls voltage lessthan 1.0 V?
- Sub6iitut€ r known€ood ECtt /PCM and rccheck. ll sYmP-
tom/indication 9oe3.waY,replaca the original ECM/PCM- See the ai. condhionGr in3p€c-tion lsee soc{ion 221.
11-207

ldle Control System
ldle Speed Setting
Inspection/Adiustmenl
'96, '97 Dl6Y5. '96 - 00 Dl5Y8 sngine with M/T
NOTE:
. Before setting the idle speed, check the following
items:- The MIL has not been reported on.- lgnition timing- Spark plugs- Air cleaner- PCV system
o (Canada) Pull the parking brake lever up. Start the
engine, then check that the headlights are off.
1. Start the engine. Hold the engine at 3.000 rpm withno load (taansmission in neutral) until the radiatorfan comes on, then let it idle.
2. Connect a tachometer.
3. Disconnect the IAC valve connector.
4.lf the engine stalls, restart the engine with the accel-
erator pedal slightly depressed. Stabilize the rpm at1,000, then slowly release the pedal until the engineidles.
Check idling in no-load conditionsr headlights. blowerfan. rear defogger, radiator fan, and air conditioner
are not operating.
ldle spsed should be:
450 1 50 rpm
11-220
Adjust the idle speed, if necessary, by removing thecap and turning the idle adjusting screw.
NOTE; After adjusting the idle speed in this step,recheck the ignition timing (see section 23).
lf it is out of spec, go back to step 4.
IDLE
6. Turn the ignition switch OFF.
7. Reconnect the 2P connector on the IAC valve, then
do the ECM reset procedure.
8. Restart and idle the engine with no-load conditionsfor one minute, then check the idle speed.
NOTE: (Canada) Pull the parking brake lever up.Start the engine, then check that the headlights areoff.
ldle sp€sd should b€:
670 i 50 rpm IUSA)750 t 50 rpm {Canada}
9. ldle the engine tor one minute with headlights {Low)ON. and check the idle speed.
ldle speed should be:
750 :r 50 rpm
10. Turn the headlights off. ldle the engine for oneminute with heater fan switch at Hl and air conditioneron, then check the idle speed.
ldle speed should be:
810150 rpm
NOTE: lf the idle speed is not within specification,see Symptom Chan on page 11-84.

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'96.'97 D16Y5 engine with CVT,'96 - 00 D16Y8 ongins
with A/T and'96 - 00 Dl6Y7 €ngine
Adiust the idle speed using a Honda PGM Tester if pos-
sible. lf not, use the following procedure:
NOTEI
. Leave the IAC valve connected
. Betore setting the idle speed. check the following
items:- The MIL has not been reported on'
- lgnition timing
- Spark Plugs- Air cleaner- PCV system
1. Connect a tachometer.
2. Start the engine. Hold the engine at 3,000 rpm wirh
no load (in Park or neutral) until the radiator fan
comes on, then let it idle.
3. Check the idle speed with no-load conditions: head-
iights, blower fan, rear defogger, radiator fan, and
air conditioner are not operatlng
ldl€ spoed should be:
USA:
D16Y5 engine with CVT, D16Y7 engine with A/T'
Dl6YB engine with A/T:
700 :r 50 rpm (in E or El Positionl
D16Y7 engine with M/T:
670 i 50 rpm
Canada:
Dl6Y8 sngin€, Dl6Y7 engins:
M/T750 t 50 rpm
NT750 1 50 rpm (in E or El Position)
Adjust the idle speed, if necessary, by removing the
cap and turning the idle adiusting screw 1/2-turn
clockwise or counterclockwise
D16Y5, D16Y8 engine:
IDLEADJUSTING
Dl6f, ongine:
NOTE: When you remove the ACL housing, do not
disconnect the IAT sensor connector
After turning the idle adjusting scrow 1/2-turn'
check the idle speed again. lf it is out of spec, turn
the idle adjusting screw 1/2-turn agaan'
NOTE: Do not turn the idle adjusting screw more
than 1/2-turn without checking the idle speed'
ldle the engine for one minute with heater fan
switch at Hl and air conditioner on, then check the
idle speed.
ldle speed should be:
M/T810150 rpm
A/T. CvT810 t 50 rpm (in El or E Position)
NOTE:
. Do not turn the idle adjusting screw when the air
conditioner is on.
. lf the idle speed is not within specification. see
Symptom Chart on page 11-84 (cont'd)
11-221