
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

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

Fuel Supply System
- Repair op€n or short in thewir€ betlveen the PGM-FI mainrelay and the No. 31 STARTERSIGNAL 17.5 A) fuse.- RoDlace the No. 31 STARTERSIGNAL {7,5 Al tuse in theunder-dash luse/rolay box.
ls there battery voltage?
Check tor an open in the wire(FLR linel:1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector A (32P).
3. Check for continuity betweenthe PGM-FI main relay 7P con-nector terminal No. 1 and ECM/PCM connector terminal A16.
Repair open in the wir6 botweenthe ECM/PCM (A161 and rhePGM-FI main relay.
Check for an open in the wires{lGPl, lGP2 line3):1. Reconnect the ECM/PCM con-nector A {32P).2. Reconnect the PGM-Fl mainrelay connector.3. Turn the ignition switch ON (ll).
4. Measure voltage betweenECN4/PCM connector terminals81 and 820, and betweenBg and 820.
- Repair open in the wire bet-ween th. ECM/PCM (81, Bg)snd the PGM-F main rolay.- Roplace th€ PGM-FI main relav.
Chock tor an open in th6 ECM/PCM:1. Turn the ignition switch OFF.2. Measure vo ltage betweenECM/PCM connector terminalsA16 and 82 when the ignitionswitch is first turned ON lll) for
Sub3titute . known-good ECM/PCM and rochock. lf prescribedvohege is now available, replacethe original ECM/PCM.
ls there 1.0 V or less?
Chock the PGM-Fl m.in r6lay{see p.ge 11-2371.
PGM-FI Main Relay (cont'd)
_._(9x . qq -gqerll _
PGM.FI MAIN FELAY 7P CONNECTOR {C4€}FLR
ECM/PCM CONNECTORS
A (32P1
Wire side ot female terminals
Wire side of fem6le terminals
ECM/PCM CONNECTOR B {25PIIGP2 {YEL/BLKI
IGRN/YEL}
IGP2(YEL/BLKI
Wire side of female terminals
11-240
IJ
'l'

Electrical Troubleshooting ('96 - 98 Modelsl
Troubleshooting Flowchart - Linear Solenoid
NOTE: Record all freeze data before vou troubleshoot,
Po$ible Caus6
. Disconnoctod lineaJ solonoidconnectot. Short or open in linoar solenoid
' Faulty linoar solonoidLINEAR
Terminal side ol male terminals
PCM CONNECTOR B I25PI
Wire side of female terminals
SOLENOID CONNECTOR
l;r]l
TT
YI
LI
REDWHT
OBO ll Scan Tool indicates CodeP176a.Self-diagnosi3 E indicatorlight indicates Code 16,
Measure Linear Solenoid Resist-ance at the Solenoid Connecto.:1. Turn the ignition switch OFF.2. Disconnect the 2P connectorlrom the linear solenoid connector,3. Measure the resistance ofthelinear solenoid.
ls the resistance approx. 5.0 O?
Check Linear Solenoid for a ShonCircuit:1. Disconnect the B 125P) connec-tor from the PCM.2. Check for continuity betweenthe body ground and the B1terminal and 82 terminal inda-vidually.
Repair short in the wires bgtwoenthe Bl and 82 terminab and thelineti solsnoid.
Meaaure Linoar Solenoid RGi3t-anc€:1. Connect the linear solenoidconnector.2, Meas u re the resistancebetween the 81 and 82 termi-nals,
Ropair looso terminal or open inthe wires botwe€n the 81 and 82telminals end the linear solenoid.
ls the resistance approx. 5.0 O?
To page 14-73
14-72

Electrical Troubleshooting ('gg - 00 Models)
Troubleshooting Flowchart - A/T Gear position Switch (Short)
NOTE: Record all freeze data before you troubleshoot.
Po$ible Cause
' Short in A/T go.r positionswhch wire. Faulty A/T goar position switch
NOTE: Code P1705 (5)the PCM received twoinputs at the same time.
is caused whengear position
PCM CONNECTORS
LGl (BRN/BLK) LG2 (BRN/BLKI
Wire side of femaleterminals
B {25P1 llD (16P1
. OBD ll Scan Tool indicrtB CodeP1?05.. Solt-diagno3i3 E indicatorlight blink. tive times.
Observo the A/T Gear PositionIndicetori1. Turn the ignition switch ON fit).2. Observe the lVT gear positionindicator, and shift each posi,!on separately.
Does any indicator stay onwhen the shift lever is not inthat position?
The sFtom is OK at thi3 time.Check the wi.e harness for dam-aga.
Do all gear position indicatorsgo out?
Moasure ATP R Voltage:1. Shift to all positions otherthanE.2. Measure the voltage betweenthe DG and 82O o( 822 terfii-nats.
Check tor short in the wirebatwoen tha DB terminal and theA/T go.r porhion switch or A/Tg6ar po3ition indicator, andchock for opon in the wiresbetween the B20 and B22 t€rmi-n.ls and body ground (G10 . tfwir€c rro OK, chsck fo. loo3e tel-ftinal fit in the FCM connectors. llnoceisary, substiiute e known-good FCM and r€check.
ls there battery voltage?
To page 14-85
\
14-84

Electrical Troubleshooting ('99 - 00 Models)
Troubleshooting Flowchart - E Indicator Light Does Not Come On
FCM CONNECTOR B (25P}
LGl {8RN/ALKI{BRN/8LK}
Wire side ol temale terminals
LGl IBNN/BLK} LG2 {BRN/BLK)
i2t5 6q
910t7
LG2
o) (o
The Pll indicator light does notcome on when the ignitionswitch is fi.st turned ON (ll). lltshould come on for about twoseconda.l
Check the Service Check Con-nector:Make sure the special tool (SCS
Service Connector) is not connect-ed to the service check connector?
ls the specialtool {SCS ServiceConnector) is not connected tothe seNice check connector.
Disconnect the special tool fromthe service check connector andr6check.
Check the Dll lndicator LightiShift to d position.
Check for loose terminal fit in thePCM connecto13. It necessary.sub3titute a known-good PCMand recheck.
Does the @ indicator lightcome on?
Check the Ground Circuit:1. Turn the ignition switch OFF.2. Disconnect the B (25P) con-nector from the PCM.3. Check for continuity betweenthe 820 terminal and bodyground, and between the 822terminal and body ground.
Repair open in the wiresbetween the B20 rnd 822 termi-nals and ground (G101), andrep.ir poor ground (G1011.
Measure Power Supply CircuitVoltage:1. Turn the ignition switch ON {ll}.2. Measure the voltage betweenterminals B1 and 822 andbetween terminals Bg and820.
Repair open or short in the wi.obetween th6 81 and/or 89 termi-nals and the PGM-FI main relav,and between th€ PGM-FI mainr€ley rnd the under-hood tus€/relay box.
To page 14''103
14-102

Electrical Troubleshooting ('96 - 9g Models)
Troubleshooting Flowchart - A/T Gear position Switch (Short)
NOTE: Record all freeze data before you troubleshoot.
Posrible Cause
. Short in A/T go.r positionswitch wire. Faulty A/T g€ar polition switch
NOTE: Code P1705(5) is caused whenthe TCM receives two gear positionInputs at the same time.
TCM CONNECTOR A {26P}
Wire side of female terminals
To page 14-245
. OBD ll Scan Tool indicates CodeP1705.. Seif-diagnosis @ indicator lightblinksfive times.
Obsorve the A/T gear positionindicetor:1. Turn the ignition switch ON1[).2. Observe tho Ay'T gear positionindicator, and shift to eachposition separately.
Th6 lyrtcm i3 OK at thi. tima.Check the wi.s hamels for drm.ag9.
Do any jndicators stay on when thesh;ft lever is not in that position?
Measure ATP R Vohage:1. Shift to all positions other thanE.2. Measure the voltage betweenthe 411 and A13 or A26 termi-nats.
Check for sho.t in tho wireb€twoon the Al1 t rminaland th6A/l ge.r polhion switch or A/Tgear position indicstor. lf wilo isOK check for loos6 TCM conncc-tora. It nocassery, subrtitute aknown-good TCM and r€chsck.
ls there approx. 10 V?
Measure ATP NP Volt.ge:1. Shift to all positions otherthan @ or @.2. Measure the voltage betweenthe A10 and 413 or 426 termi-nals,Ch.ck tor 3hort in th€ wircb€twe€n thc Al0 termin.l andthe A/T 96r. porition indicrtor,or a short in the wilea b?twecntho A/T gerr porition indic.to.and the A/T geer positionswitch. It wires ar6 OK, chsck forloose TCM conn.clols. ll nccNe3-sa.y, substituto a known-goodTCM rnd locheck.
ls there approx. 10 V?
Measure ATP O Vohage:1. Shift to all positions otherthanE,2. Measure the voltage betweenthe Ag and A13 or 426 terminals.
Checl tor short in the wirelr€tweon tho A9 terminal and theA/T g6a. position 3witch. lf wireb OK. check tor loos€ TCM con-nectors. lf nocelsary, substhute aknown-good TCM and rechack.
ls there approx. '10 V?
14-244
b