1999 HONDA CIVIC Ignition

[F16551l Th" ""un toot indicates Diagnostic Trouble Code (DTC) P1681: TIVA,/TMB signal line failure
Problem verification:1. Do the ECM Reset Procedure.
2. Drive the vehicle Ior several
miles at varying speeds
lnt.rmittent failure, system is OK
at ihis time. Check tor Poor con-
nections or loos€ wires at C131
llocated under right side of dash),
C438 ITCM) and ECM.
ls DTC P1655 indicated?
Check lor an oPen in the wire(TMA line):1. Turn the ignition switch OFF
2. Disconnect ECM connector C(31P)from the ECM
3. Turn the ignition switch ON (ll).
4- Measure vo ltag e between
ECM connector terminal Cg
and body ground.
Check for a short in the wire
ITMA line,:Measure voltage between TCM
22P connector terminal No 7 and
body ground.ls there battery vohage?
Ropair shod in the wire bstwe€n
the EcM (C!l) and the TcM.ls there battery voltage?
Check for an open in the wire
{TMB line}:1. Turn the ignition switch OFF
2. Reconnect ECM connector c(31P).
3. Disconnect the 22P connector
from TCM.4. Turn the ignition switch ON (ll).
5. Measure vo ltage between
TCM 22P connector termlnal
No. 6 and body ground.
Repair open in the wire between
th€ EcM {Ca) and the TcM.
Check for a 3ho.t in the wire
{TMB lin6,:Measure voltage between ECM
connector terminal C30 and bodyground,
ls there battery voltage?
Substitute a known'good ECM
and recheck. It symPtom/indica'tion goes away, teplace the origi-
nal ECM.
Reoair short in the wile b6tween
the ECM {C30} and the TCM.ls there baftery voltage?
f,epair open in the wire between
the EcM (C30) and the TcM.
IJA/T Signal (TMA/TMBI ('96 - 98 Dl6Y5 engine with GW)
ECM CONNECTOR C 131P}TMA IGRYI
fcu22PCONNECTOR
ll
TMB*{PNK}
231678910
1t'12131415161718
232a252930
Wire side oI temale
terminals
tl,
1 1-189

I
L
1D16Y5, D16Y8 engine with M/T 81642 engine)I
D16Y7 engine:
{From page 11-192)
Check the IAC valve:Disconnect the 3P connector from
the IAC valve.
Check the IAC valve:Disconnect the 2P connectorfrom the IAC valve.
Does the engine speed drop or
the engine stall?
Adiust the {base} idle speod (see
page 11-220 - 2231.It it's impos-
aible, clean the ports in lhe throt'
tle bodv,
(From page 11-192i
Check Ior vacuum leaks:1. Turn the ignition switch OFF.2. Remove the intake air ductfrom the throttle body.
3. Start the engine and let it idle.
4. Put your finger on the lowerpon in the th.ottle body.
Ch€ck tor vecuum loaks, m.kesure the throttle valve is com_pletaly closed, end repair as nec-Does the engine speed droP?
Adiust the idle speed (see page
11-220 - 2231. lf it's impossible,
reolace the IAC velve.UPPERPORT
1 1-1 93

ldle Control System
ldle Air Control (lACl Vatve ('96 - 98 Dl6ys, Dl6yB engine with M/Tl
The scan tool indicates Diagnostic Trouble Code (DTC) P1508: A problem in the ldle Air Controt flAC) varvecircuit.
The IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the ECM inorder to maintain the proper idle speed.
IAC VALVE 2P CONNECTOR ICl3A)
,flrcerh-:J iYEL/BLKI
!.__-,/ -lt(v)
-T-=
Wire side of female terminals
tAcv(BLK/
ELUI
ECM CONNECTOR A I32PI
Wire side oI lemal€ terminals
VALVE
6a10ll12t3r5t6l7t8t920232a
t*25&a2A3o
The MIL hss b€on repo.ted on.DTC P'l508 i. itorod.
Problem vorification:1. Do the ECM/PCM Reset Pro-cedure,Start the engine, and warm ituP to normal operating tem-perature.
Intormittont t!llur., sy.tcm b OKat thb tim6. Chsck fol poor con-ncctionr or loo3e wirot at C138(lAC valv.l.nd ECM.
ls DTC P1508 indicated?
Check for an opcn in the wiro(lGPl line):1. Turn the ignition switch OFF.2. Disconnect the IAC valve 2Pconnector.3. Turn the ignition switch ON (ll).
4. Measure vohage between bodyground and the IAC valve 2Pconnectorterminal No. 2.
R.prir opan in the wiro botwa.nIAC valv..nd PGM-FI main r.l.y.
Chock for an opon or sho in thewire (IACV linal:1. Turn the ignition switch OFFand reconnect the IAC valveconnector.2. Disconnect the ECM connectorA (32P).
3. Turn the ignit;on switch ON (ll).4. Measure voltage betweenbody ground and ECM con-nector terminal A12.
(To page 1l-195)
11-194

ldle Gontrol System
ldle Air Control (lAG) Valve ('99 - 00 Dl6Y8 engine with M/T, Bt6A2 enginel
[Fl50g l ]h" scan tool indicates Diagnostic Trouble Code (DTC) P1508: A problem in the ldle Air Controt AC) vatve- CtrCUtt.
The IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the ECM inorder to maintain the proper idle speed.
IAC VALVE 2P CONNECTOR IC138'
la rcprI - {YEL/8LKI 2t--d,
Y-=
Wire side ot female terminals
Wire side of lemale terminals
VALVE
The MIL has boon r€oorted on.DTC P1508 is srored.
Probl6m verification:1. Do the ECM/PCM Reset Pro-cedure.2. Start the engine, and warm itup to normal operating lem-perature.
Intermittent tailure, system is OKat this timg. Check to. poor con-noctions or loose wires at C138{lAC valvel and ECM.
ls DTC P1508 indicated?
Ch6ck for an open in the wir€{lGPl lino}:1. Turn the ignition switch OFF.2. Disconnect the IAC valve 2Pconnector.3. Turn the ignition switch ON (ll).
4. Measure voltage between bodyground and the IAC valve 2Pconneclor termina I No.2,
Repair opon in the wire bgtwoenIAC valve and PGM-Fl main relay.
Check tof an open or short in thewire {IACV line}l1. Turn the ignition switch OFFand reconnect the IAC valve
2. Disconnect the ECM connectorB {25P).3. Turn the ignition switch ON (ll).
4. Measure voltage betweenbody ground and ECM conn€ctor terminal 823.
(To page 11-197)
1 1-1 96

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

t
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

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