1999 HONDA CR-V Idle air

38 - 00 modeb:
Problem verification:1. Do the ECM/PCM Reset Proceoure.2. Stan the engine.3- Turn on the headlights.Intermittent feilure, sysl.m is OKat this time. Check for ooor con-nections or loose wires at C354(ELDI and at the ECM/PCM.
ls DTC P1298 indicated?
Check lor an open in the wire(lG1 line):'1. Turn the ignition and head-lights OFF.2. Disconnect the ELD 3P connector.3. Turn the ignition switch ON (ll).
4, Measu re voltage betweenbody ground and the ELD 3Pconnector terminal No. '1.Reprir open or short in th6 wirebotweon the No. 15 ALTERNA-TOR SP SENSOR {7.5 Al fuse inthe under-drah fuse/relay boxand the ELD.
Check tor an opon in tho wire{GND line}:1. Turn the ignition switch andheadlights OFF.2. Disconnect the ELD 3P connector.3. Check for continuity betweenbody ground and the ELD 3Pconnector terminal No. 2,
Repair opon in the wire betweenthe ELD conneclor and GilO2.
Ched( fo. an op€n in the wir€ (EL linel:Check for continuity between theELD 3P connector terminal No. 3and ECM/PCM connector termi-nalA30.
Repair op€n in tha wile botwecnthe EcM/PCM lA30l .nd rhe ELD.
Check for s malfunction in lhe ELD:1. Reconnect the ELD 3P con-nector.2. Start the engine and allow itto idle.3. While measuring voltagebetween ECM/PCM connectorterminals A30 and 820, turnthe headlights on (low).
Substiiute a known-good ECM/PCM and recheck. It symptom/indication goos away, replacethe original ECM/PCM.
ELO 3P CONNECTOR {c35/rl
Wire side of female terminals
Wire side of female terminals
Wire side ot temale terminals
ELD 3P CONNECTOR {C35,lt
EL IGRN/RED}Wire side of femaletermrnars
ECM/PCM CONNECTORS
A l32P)
11-141
www.emanualpro.com

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
www.emanualpro.com

ldle Control System
ldle Control System
I P0505 | The scan tool indicates Diagnostic T.ouble Code (DTCI PO5O5: ldlecontrol svstem mattunction.
NOTE: lf DTC P1508 is stored at the same time as DTC P0505, troubleshoot DTC P1508 first. then troubleshoot DTC p0505.
Possibls Cause
. IAC valve mechanical malfunction. Throttle body clogged port, improper adlustment. Intake manifold gasket leakaging. Intake air hose loose leakaging. Vacuum hose leakaging
a ECT sensor incorrect output. Throttle Position sensor incorrect output
Troubleshooting Flowchart
The MIL has been reDorted on.DTC P0505 is sto.ed.
Problem verificationi1. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator Ian comes on, thenlet it idle.2. With the scan tool, check thelollowing items.- Throttle position should beapprox. 10% with the throt-tle {ully closed.- Engine coolant temperature shorJld be 194 - 205'F(90 - 96"C).lf they are not within thespec., repair the faulty sen-sor circuit.3 Check the engine speed atidle with no-load conditions:headlights, blower fan. reardefogger, radiator lan, and airconditioner are not operaling,
Inte.mittent failure. syltem is OKat this time.ls it 750 {730)* i 50 rpm?
ls il 700 (680)' rpm or less?
{To page 11-151)(To page 1'l-151)
l:'99 - 00 models
www.emanualpro.com

(From page 11-150)
{From page 11-150}
THERMO VALVE(A/T onlyl
Check the IAC valve:Disconnect the 2P connector from
the IAC valve.
Does the engine speed droP
or the engine stall?
Adiust the (basel idl€ speed lseepage 11-169, 1t0). Itihe ba3e idle
speed cannot be adiust€d, clean
the Dorts in the throttle body.
UPPER
Check the tast idle lhermo valve:
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 throttle body.
Check engine cool.nt level and for
air in the cooling sy3lem. lf OK,
reolace the f.st idle thermo valve.Does the engine speed drop?
Put your Iinger on the uPPer Portin the throttle body.
Check for vacuum leaks, make
sure the throttle valve is com'pletely clo3ed. and repair as nec-Does the engine speed droP?
Adjust the idle spoed lsee Page11-169. 1701. lf the adiustmentdoes not correct lhe problem,
r.olace the IAC valve.
www.emanualpro.com

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)
www.emanualpro.com

Alternator (ALT) FR Signal
This signals the ECM/PCM when the Alternator (ALTI is charging.
,97 modet: PCM GONNECTORS
wire side of female terminals
ALT CONNECTOR (C1O5I
lPr-F- ALT F
lll2llw|{frREDl|3.r-'l-
lruueen wne
c (31P|
wire side ol f€male terminals
PCM CONNECTOR C I31P)
3Pr
JUMPERWIRE
Inspection ot ALT FR Signal.
Check lor a short in the wire
{ALT F line}:1. Disconnect the 4P 13Pi* connector from the ALT.2. Turn the ignition switch ON (ll)
3, Measure voltage betweenPCM connector terminals C17
and A9.Check for a short in the wire(ALT F linel:1. Turn the ignition switch OFF.2. Disconnect the negative bat'tery cable from the battery.3. Disconnect PCM connector C(31P).
4. Check for continuity betweenbody ground and PCM connector terminal C17.
ls there approx. 5 V?
Check th€ ope.ation of the ALT:
1. Turn the ignition switch OFF2. Reconnect the ALT 4P {3Pi*connector to the ALT.3. Start the engine. Hold theengine at 3,000 rpm with no
load (in Park or neutral) untilthe radiator fan comes on,
then let it idle.4. Measure voltage betweenPCM connector terminals C17and A9.
Ropeir short in the wir6 betweonthe PCM lC17l and the ALT.
Substitut. a known-good PCM
and recheck. lf prescribed volt-
age is now availablo, replace the
originalPCM.
Does the voltage decrease when
headlights and rear defogger are
turned on?ALT FR signal b OK.
Ch€d( for an op€n in tho wire IALTF linel:1. Turn the ignition switch OFF.2. Disconnect the negative bat-tery cable lrom the battery.3. Disconnect PCM connector C(31P).
4. Disconnect the 4P (3P)* con-nector lrom the ALT.5. Connect the ALT 4P (3P)* con-nector terminal No. 4 (No. 1)*to body ground with a iumper
6. Check for continuity betweenbody ground and PCN4 con'nector terminal Cl7.
Repair open wi.e between thePCM lCl7l and the ALT.ls there continuity?
ALT F IWHT/REDI
Wire side of female terminals
1 1-159
www.emanualpro.com

ldle Control System
Fast ldle Thermo Valve lA/T)
Description
To prevent erratic running when the engine is warming
up, it is necessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger.
When the engine is cold, the engine coolant surround-
ing the thermowax contracts the plunger, allowing addi-
tional air to be bvDassed into the intake manifold so that
the engine idles faster. When the engine reaches operat-
ing temperature. the valve closes, reducing the amount
of air bypassing into the intake manifold.
IDLEADJUSTING
IDLETHERMOVALVE
AIR BYPASS VALVE
11-168
Inspgction
NOTE: The fast idle thermo valve is factory adjusted; it
should not be disassembled.
1. Remove the intake air duct from the throttle body.
2. Start the engine,
3. Put your finger over the lower port in throttle body,
and make sure that there is air flow with the engine
cold (engine coolant temperature below 86"F, 30'C).
lf there is no air flow, replace the fast idle thermo
valve and retest,
O-RINGSReplace.
11.0 kgfl.m, 7.2 lbl.ftl
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.
Check that the valve is completely closed. lf the valve
is leaking, the idle speed will drop when you cover the
lower pon. Check the engine coolant level and for air
in the engine cooling system {see section 10). lf the
cooling system is OK, replace the fast idle thermo
valve and recheck.
www.emanualpro.com

ldle Speed Setting
Inspoction/Adiustmont
37 modsl:
NOTE:
. Before setting the idle speed, check the following
items:- The MIL has not been reportsd on.- lgnition timing- Spark plugs
- Air cleaner- PCV system
. lcanada) Pull the parking brake lever up. Stan 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 or a Honda PGM Tester.
Disconnect the 2P connector from the ldle Air Con-
trol (lAC) valve.
IAC VALVE
lf the engine stalls, restart the engine with the accel-
erator pedal slightly depr6ss6d, Stabilize the rpm at
1,000, then slowly release the pedal until the engine
idles.
Check idling in no-load conditions: hsadlights,
blower fan, rear d€fogger, radiator fan, and air con-
ditioner are not operating.
ldle spood should b.:
{80 t 50 rpm {in Park or noutr.ll
IDLE
7.
Adjust the idle sp6ed,
idle adjusting screw.
if necessary, by turning the
Turn the ignition switch OFF.
Reconnect the 2P connector to the IAC valve, then
remove the BACK UP (RAD|Ol (7.5 Al fuse in the
under-hood fuse/rslav box for 10 seconds to reset
the PCM.
Restart and let the engine idle with no-load condi-
tions for one minute, then check the idle speed.
NOTE: (Canadal Pullthe parking brake lever up. Stan
the engine, then check that the headlights are off.
ldlo Ep€ed rhould be:
75O t 50 rpm (in P.rk or noutr.ll
Let the engine idl6 for one minute with the head-
lights (Low) ON, and check th€ idl€ speed.
ldle lpcod 3hould bo:
750 t 50 ]pm (in Park or nautlal)
Turn the headlights off. Let th€ engine idle for one
minute with the headlights (Low) ON, heater fan
switch at Hl and air conditioner on. then check the idle
sDeeo.
ldl. specd should b6:
7d) 1 50 rpm {in Park or nautral}
lf the idle speed is not within specification, see the
symptom chart on page 11-64. (cont'd)
1 1-169
www.emanualpro.com