Page 348 of 1395
PGM-FI System
Crankshaft Position/Top Dead Center/Cylinder Position (CKP/TDC/CYP) Sensor
The scan tool indicates Diagnostic Trouble Code (DTC)
Center/Cvlinder Position tCKP/TDC/CYP) sensor circuit.
P1359:A problem in the Crankshaft Position/Top Dead
- The MIL has been reoorted on.- DTC P1359 is stored.
Problem verific.tion:1. Do the ECM/PCM Reset Proce-dure.2. Start the engine. lf the enginewon't start, crank it continu-ouslyfor at least 15 seconds.
Intermitteni lailure, system is OK.Check for ooor connections orloos€ wires al C121 {distributor}and at the ECM/PCM.
ls DTC P1359 indicated?
Check for poor connections orloose wires between the distribu'tor and the EcM/PcM.
Substitute a known-good ECM/PCM, and recheck. ll symplom/indication goes away, replace theoriginal ECM/PCM.
11-146
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Page 349 of 1395
ECM/PCM Internal Circuit
lFi6oil Th" """n tool indicates Diagnostic Trouble Code {DTC) P1607: An ECM/PCM Internal Circuit Problem.
- The MIL has been reoorted on.- DTC PlmT is slor6d.
Problom veritication:1. Do the ECM/PCM Reset Pro
2. Turn the ignition switch ON (ll).
3, Wait three seconds,
ls DTC P1607 indicated?
Sub3tiiut€ a known-good ECM/PCM and recheck. lf symptom/indication goes away, replace theoriginal ECM/rcM.
11-147
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Page 351 of 1395
ldle Control System
System Description
The idle speed of the engjne is controlled by the ldle Air Control (lAC) Valve'
The valve changes the amount of air bypassing into the intake manifold in response to electric current controlled by the
ECM/PCM. When the lAc valve is activated, the valve opens to maintain the proper idle speed.
YEL/ From PGM'FI
BLK TMAIN RELAY
VARIOUSSENSORS
4.
IAC VALVE
INTAKE MANIFOLD
After the engine starts, the IAC valve opens for a certain time. The amount of air is increased to raise the idle speed
about 150 - 300 rpm.
when the cootant temperature ts row, the lAc valve is opened to obtain the proper fast idle speed The amount o{
bvoassed air is thus controlled in relation to the engine coolant temperature
When the idle speed is out o{ specification and the scan tool does not indicate Diagnostic Trouble Code (DTC) P0505
or P1508, check the following items:
. Adjust the idle speed (see page 11-169, 170)
. Air conditioning signal (seepagell-1551
. ALT FR signal (see page 1l-159)
. Starter switch signal (see page 11-16'1)
. A,/T gear position signal (see section 14)
. PSP switch signal (seepagell-162)
. Brake switch signal (see page 11-165)
. Fast idlethermovalve (see page'11 168)
. Hoses and connecttons. IAC valve and its mounting O-rings
lf the above items are normat, suDslitute a known-good IAC valve and readjust the idle speed {see page 11-169, 170)
lf the idle speed still cannot be adjusted to specification (and the scan tool does not indicate DTC P0505 or Pl508)
after IAC valve reolacement, substitute a known-good ECM/PCM and recheck lf symptom goes away' replace the
original ECM/PCM.
11-149
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Page 354 of 1395
ldle Control System
ldle Air Control llAC) Valve
The scan tool indicates Diagnostic Trouble Code (DTC) Pl508: A probtem 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/PCM inorder to maintain the proper idle speed.
37 model;
IAC VALVE 2P CONNECTOR {C132}
,f rcp'# IYEL/BI.(II2f-1-d)
Y
Wir€ side of female terminals
PCM CONNECTOR A I32PI
tacvIBLK/BLU)
From AIR To INTAKECLEANER MANIFOLD
Wire side of female terminals
The MIL has beon .eport€d on.OIC Pl508 is sto.ed.
Problem veiification:1. Do the PCM Reset Procedure.2. Start the engine, and warm itup to normal operating tem-perature.
Inte.mittent failure, systcm b OKat thi3 time. Check tor poo. con-nections or loose wircs at C132(lAC v.lvel and at the PCM.
ls DTC Pl508 indicated?
Check lor an open in the wir6{lGPl lins}: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 2Pconnector term inal No.2.
Repair open in the wire trctwoontha IAC v!lv6 and the PGM-Flmain relly.
Chock for an opan o. short in thowi.e (lACv linel:1. Turn the ignition switch OFFand reconnect the IAC valve2P connector.2. Disconnect the PCM conneclorA (32P).
3. Turn the ignition switch ON {ll).4, Measure voltage betweenbody ground and PCM con-nector terminal A12.
{To page 1l-153)
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Page 355 of 1395
Bepair op€n or short in the wire
betweon th€ PCM {A121 and the
IAC vrlve.ls there baftery voltage?
Check the IAC valve function:Momentarily connect PCM con'nector terminals A12 and A10with a iumoer wire severaltimes,
Does the IAC valve click?
Substitute . known-good PCM
and r€check, lt 3ymptom/indica-tion goes away, replaco the origi_nalPCM,
(From page 11-152)
Wire side of female terminals
1-153
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Page 356 of 1395
The MIL has boen r.ported on.DIC Pl 508 b 3tored.
Problem veritication:L Do the ECM/PCM Reset Pro-cedure.2. Start the engine, and warm itup to normal operating tem-perature.
Int€rmittent failure, systom is OKal lhis timo. Check lor poor con-nections or looro wirca at C132(lAc vrlvel and .t rho EcM/PcM.
ls DTC P1508 indicated?
Chock tor an open in the wir6llGPl linel: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 2Pcon nector termina I No, 2.
Repair opon in the wira botwoonthe IAC valve and tho PGM-FImain aalay.
Check tor an open or short in thewire (IACV linel:1. Turn the ignition switch OFFand reconnect the IAC valve2P connector.2. Disconnect ECM/PCM con-nector B {25P).3. Turn the ignition switch ON {ll}.4. Measure voltage betweenbody ground and ECM/PCMconnector terminal 823.
Ropair open or short in thg wirebetween tho ECM/FCM lB23l andthe IAC valve.
ls there battery voltage?
Check the IAC valve func,tion:Momentarily connect ECM/PCMconnector terminals 823 and 82with a jumper wire several times.
Does the IAC valve click?
Subslitute . known-good ECM/PCM .nd rechock. lf symptom/indication goes aw.y, replac.th€ original ECM/PCM.
ldle Air Control (lAC) Valve {cont'd}
'98 - 00 models:
IAC VALVE 2P CONNECTOR {C132I
F rcpt*l tYELrBLxlI2/'-- rf)
Y
Wire side ot fem.le terminals
ECM/PCM CONNECTOR B (25PI
Wire side of female torminals
258
9'to1l13t7
1920212223
tAcv(BLK/BLUIv
PG1{BLKI
12 | t3 4 58
910 111317
1920 | 121)22
tAcv(BLK/
BLU)JUMPER WIRE
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Page 357 of 1395
Air Conditioning Signal
This signals the EcM/PcM when there is a demand for cooling from the air conditioning system.
'97 modol:
Wire side of lemale terminals
PCM CONNECTOR C (31PI
ACS IBLU/RED)
PCM CONNECTOR A (:TIPI
(cont'd)
1 1-1 55
Chock for a shorl in thc wiro(ACS linol:1. Turn the ignition switch OFF.2. Disconnect the A/C pressure
switch 2Pconneclor.3. Turn the ignition switch ON (ll).,1. [Ieasu re voltage betweenPCM connector terminals C5
and A9.
Check for . .hon in the wire IAGSlinel:1. Turn the ignition switch OFF.2. Disconnect PCM connector C(31P).
3. Check for continuity betweenbody ground and PCM con-nector torminal C5.
Reoaii short in tho wire b€twoenrh6 PCM (Csl and the A/C pres-
3urc 3witch.
- Subcdtrte a known{ood PCMand recheck. lf pr6actibed volt-age is now av{ilable, roplacethe origind PCM,- Soe the eir conditionor in3p€c-lion lsee soction 221.
Check tor an opon in the wite(ACC lino):1. TLrrn the ignition switch OFF.2. Roconnect the A/C pressure
switch 2P connector.3. Turn the ignition switch ON (ll).
4. Momenta rily connect PCMconnector terminals A9 and417 with a iumper wire sev'eraltimes,
Wire side of female terminals
JUMPER WIRE
(To page 11-156)Wire side oI Iemale terminals
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Page 358 of 1395
ldle Gontrol System
Air Conditioning Signal (cont'dl
(From page 11-'155)
JUMPERWIRE
UNOER.HOOD FUSE/RELAYBOX 9P CONNECTOR tqt52)
123I
56I
ACC IBLK/RWire side ofACC IBLK/REDIWire side of femaletermrnats
A t32PlPCM CONNECTORS C t3rp)
Wire side ol lemale terminals
Ch6ck for an open in th€ wire(ACC linel:Momentarily connect the under-hood fuse/relay box 9P connectorterminal No.5 to body groundwith a jumper wire several times.
ls there a cl;cking noise fromthe 4!/C compressor clutch?
ls there a clicking noise fromthe 4!/C compressor clutch?See air condiiioner inspection{see section 221.
Repai. op6n in the wire betwoenthe PcM (A17) and tho A/Cclutch relay.
Check the A/C operation:1. Start the engine.2. Turn the blower switch ON.3. Turn the A"/C switch ON.
Check for an open in the wire(ACS line):Measure voltage between PCMconnector terminals Ag and C5.
Does the A,/C operate?
Air conditioning signal is OK.
Repair open in the wire betweenthe PCM lCSl and the A/C awitch.ls there less than 1.0 V?
- Subqtitute a known-good FCM.nd r€ch6ck. lt 3ymptom/indi-cation goes awav, replece theoriginal rcM.- Soe th€ eir conditioner in3pec-tion (s6€ aec.tion 22).
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