Page 302 of 1681

2.
1.
1.
2.
After the engine stans, the IAC valve opens for a certain time. The amount ol air is increased to raise the idle speed
about 150 - 300 rpm.
When the coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of
bypassed air is thus controlled in relation to the engine coolant temperature.
IDLE SPEEDtrpm,
ENGINECOOLANT TEMPERATURE
140
50
104
40
-1 32
-20 0
176 ('F)
80 fcl
When the idle speed is out of specification and the scan tool does not indicate Diagnostic Trouble Code (DTC) P0505
or P'1508, check the following items:. Adiust the idle speed (see page '11-111)
' ALT FR signal (see page 11-101). Air conditioning signal {seepage'11-102)' Brake switch signal (seepagell-104)
. Starter switch signal (see page 11-1051. A,4 gear position signal (see page 1l 106) (A"/T)
. PSP switch signal (see page 11-108) (USA)
. Fast idle thermo valve (see page 11-110). Hoses and connections. IAC valve and its mounting O rings
ll the above items are normal, substitute a known-good IAC valve and readjust the idle speed (see page 'l I -1 1 l).
lf the idle speed still cannot be adjusted to specification (and the scan tool does not indicate DTC P0505 or P1508) after
IAC valve replacement, substitute a known-good ECM and recheck. lf symptom goes away, replace the original ECM.
11-97
Page 303 of 1681

ldle Control System
ldle Control System
i P0505 | fne scan tool indicates Diagnostic Trouble Code (DTC) P0505: ldle control system malfunction,
NOTE: ll DTC Pl508 is stored at the same time as DTC P0505, troubleshoor DTC P1508 first. then troubleshoot DTC P0505.
Possible Cause
. IAC valve mechanical malfunctiorr
. Fast idle thermo valve malfunction (A"/T)
. Throttle body clogged port, improper adjustment
. Intake manifold, gasket leakage
. Intake air hose loose, leakage
a Vacuum hoses leakage
. ECT sensor incorrect output
. Throttle Position sensor incorrect output
Troubleshooting Flowchart
Problem verification:1. Start the engine. Hold theengine at 3,000 rpm wath noload 1in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check thefollowing items.- Throttle position should beapprox. 10% with the throttle fully closed.Engine coolant tempera-ture should be 116 212F(80 - 100'c).lf they are not within thespec., repair the faulty sensor crrcuft,3 Check the engine speed atidle with no-load conditions:headlights, blower fan, reardefogger, radiator fan, and airconditioner are not operating,
- The MIL has been reported on.- DTC P0505 is stored.
ls it 750 t 50 rpm (81881,
818C1 engines), 800 I 50 rpm(818C5 engine)?
Intermittent failur6, svstsm is OKat this tim€.
ls it 550 rpm (81881,818C1
engines), 600 rpm {818C5enginelor less?
-98
(To page 11'99)(To page 11-99)
Page 307 of 1681

ldle
Air
Gontrol System
Gonditioning Signal
\
This signals the ECM when there is a demand for cooling from the air conditioning system'
ECM CONNECTORS
a l32Pl
LGl(BRN/BLKI
c t31Pt
ACSIBLU/REDI
wire side of femal€ torminals
;
L
LGI
JUMPERWIRE
ACS IBLU/REDI
Check lor.3hort in thG wira(ACS lino):1. Turn the ignition switch OFF.2. Disconnect the A/C pressure
switch connector and A/Cdiode connector,3. Turn the ignition switch ON (ll).
4. Measu re voltage betwo€nECM connector terminals C5and A9.
Ch.ck to.. rhorl in th. wir. IACSlincl:1. Turn the ignition switch OFF.2. Disconnect the ECM connec-tor C (31P).
3. Ch6ck {or continuity betwe€n
body ground tnd ECM con-nector terminal C5.
lsthere approx.5 V?
Rapair rhort In tho wira batwaon
th. EcM {c5l and thc A/c pre.-
sur. rwitch ot A/C diod.,
- Subtlilut I known{ood Ecttllnd raahack. lf prtactibad voft-
rgo ir now avaihbla, tcplacalh. originll ECM.- Saa tha air condhiond in.plction 1... r.ction 221.
Check lor an opan in th€ wi.a(ACC lin.l:'1. Turn the ignition switch OFF.2. Reconnect th6 A,/C pressure
switch connector and A/Cdiode connector.3. Turn the ignilion switch ON (ll).
4. Momentarily connect ECMconnector terminals A'17 andAg wkh a iumper wire severaltimes,
(To page 11"103)
IBRN/BLKI
Ial,/l l8 I r0 I rl
12't516 11alrslzo ,/ l4l a3 | 2.
aa2621zel dt
IBLK/REDI
11-102
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Page 308 of 1681

(From page t 1'102)
Ch6ck {or an op6n in the wireIACC linel:Mo m enta rily connect the A/Cclutch relay 4P connector termi-nal No. 4 to body ground with a,umper wire several times.
ls there a clicking noise fromthe A,/C compressor clutch?
ls there a clicking noise fromthe 4,./C compressor clutch?See air conditione. insoection{s€e section 22).
Repai. op6n in the wire betwe€ntho ECM lA17l and the A/C clutch
Check tor the oparation of theA/C:1. Start the eogine.2. Turn the blower switch ON.3. Turn the !y'C switch ON.
Check lor sn open in th6 wireIACS line):Measure voltage between ECMconnector terminals C5 and A9,
Air conditioning signal i3 OK.Repafu open in the wire betweenthe ECM {C5} and th€ A/C D.es-sure switch or A/C diode.
ls voltage less than 1.0 V?
- Substitute e known-good ECM.nd .echeck. lf 3ymptom/indi-cation goes away, rcplaco th€original ECM.- 56€ the air conditionor inspcc-tion {3eo soction 221.
UNDER HOOD FUSE/RELAYBOX 9P CONNECTOR tC216)
JUMPERWIREACC {SLK/RED)Wire side of temale- terminals
A {32P)
LGl(BRN/BLKI
ECM CONNECTORS
Wire side of female terminals
c (31P)
ACS{BLU/RED}
I
'1.1-103
Page 316 of 1681

ldle Speed Setting
IDLEADJUSTINGSCREW
7.
6.Turn the ignition switch OFF.
Reconnect the 2P connectors to the IAC valve and
the EVAP purge control solenoid valve, then do the
ECM reset procedures.
Restart and idle the engine with no-load conditions
for one minute, then check the idle speed.
NOTE: (Canada) Pullthe parking brake lever up.
Start the engine, then check that the headlights are off.
ldle speed should be;
Bl88l €ngine:
Mfi750 i 50 rpm
A/T750150 rpm (in Park or neutral)
818C1 engine:750 i 50 rpm
818C5 engine: 800 i 50 rpm
NOTE: 81881, Bl8Cl engines - It the idle speed
increases to *1rpm, this means the EVAP system ispurging the canister. To stop the purging termporarily.
raise the engine speed above 1,000 rpm with the
accelerator pedal, then slowly release the pedal.
*1: 81881 engine
M/T: 820 i 50 rpm
Ay'T: 840 t 50 rpm
818Cl engine
850 I 50 rpm
(cont'd)
Inspection/Adiustmont
NOTE:
. When setting the idle speed, checkthe following items:- The MIL has not been reported on.- lgnition timing
Spark plugs- Air cleaner- PCV system
. (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 with
no load (in Park or neutral) until the radiator fan
comes on, then let it idle,
Connect a tachometer.
Disconnect the 2P connectors from the ldle Air
Control (lAC) valve and the EVAP purge control
solenoid valve.
2.
5.
if the engine stalls, restan the engine with the accel
erator pedal slightly depressed. Stabilize the rpm at
1,000, then slowly release the pedal until the engine
idles.
Check idling in no-load conditions: headlights, blower
fan, rear defogger, radiator fan, and air conditioner
are not ope€tlng.
ldlo speed should be;
B188l engine:
Mlf480 :l 50 rpm
A/T480 i 50 rpm (in Park or neutral)
B18C1 engine: /t80 t 50 rpm
818C5 sngine:550 t 50 rpm
lf necessary, adjust the idle speed, by turning theidle adjusting screw.
After adjusting the idle speed, recheck the ignition
timing {see section 23). lf it is out of spec, go back
to steo 4.
Page 317 of 1681
ldle Control System
ldle Speed Setting (cont'dl
ldle the engine for one minute with headlights (Low)
ON and check the idle speed.
ldle 3peed should b€;
B1881 engine:
MIT750 t 50 rpm
750 i 50 rDm (in Park or neutrall
818C1 engine: 7501 50 nm
818C5 engine: 8001 50 rpm
Turn the headlights off. ldle the engine for one min-
ute with heater fan switch at Hl and air conditioner
on, then check the idle speed.
ldl. spood should be;
Bl8Bl ongin.:
M/T820 i 50 rpm
lvT840 t 50 rpm (in Park or neutral)
818C1 €ngino: 850 i 50 rpm
818C5 engino: 1,050 t 50 rpm
NOTE: lf the idle speed is not within specification.
see Symptom Chart on page 1!-36.
\
L
i
lIh:
lffiiltfl!
ffi
| 11-112
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I
Page 334 of 1681
Air Cleaner (ACLI
ACL Element Replacement
ACL HOUSINGCOVER
ACL ELEMENTNormal conditions:Replace air cleaner elementevery 30,000 milos (48,000 km) or24 months, whichever comes first.Severe cond;tions:{Use normalschoduleexcept in dusty conditions)Clean air cleaner elementev6ry 15,000 mil€s {24,000 km} or12 months and replace every30,000 miles (48,000 km) or24 months, whichever comes tirst.
INTAKE AIR DUCT
)
11-129
Page 343 of 1681

t"iI
Emission Gontrol System
System Description
Three Way Catalytic Converter (TWCI
\
t
The emission control system includes a Three Way
Catalytic Converter (TWC), Positive Crankcase Ventilation
(PCV) system and Evaporative Emission (EVAP) Control
system. The emission control system is designed to meet
tederal and state emission standards.
InsDeciion
!@@ Do not smoke during this procedure. Keep
any open llame away from your work area.
1. Start the engine. Hold the engine at 3,000 rpm with
no load {in Park or neutral) until the radiator fan
comes on, then let it idle.
2. Connect a tachometer.
Check and adjust the idle speed, if necessary (see
page '11-11 ! ).
Warm up and calibrate the CO meter according to the
meter manufacturer's instructions.
Check idle CO with rhe headlights, heater blower,
rear window defogger, cooling fan, and air condition-
er off.
NOTE: {Canada) Pull the parking brake lever up.
Start the engine, then check that the headlights are
olf.
CO meter should indicste 0.17o maximum.
DescriDtion
The Three Way Catalytic Converter {TWC) is used to convert hydrocarbons (HC), carbon monoxide (CO), and oxides of
nitrogen (NOx) in the exhaust gas, to carbon dioxide (COr), dinitrogen {Nr) and water vapor.
Bl8Cl engine l818Bl, 818C5 engines is similar):
FRONT OFVEHICLE
PRIMAEYHEATEDOXYGEN SENSORIPRIMARY HO2S}
HOUSING
WAYCATALYSTS
SECONOARYHEATEDOXYGEN SENSOR{SECONDARYH02St
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