NOTE:. When there is no Diagnostic Trouble Code (DTC) stored, the MIL will stay on if the SCSservice connector is connected and the ignition switch is on.. lf this svmotom is intermittent, check for:- A loose Fl E/M (15 Aifuse in the underdash tuse/relay box- A loose No. 13 FUEL PUMP {15 A) fuse in the under-dash fuse/relay box- An intermittent short in the wire between the PCM (C7) and the service check con-
- An intermittent short in the wire between the PCM (A18) and the gauge assembly- An intermittent shon in the wire betlveen the PCM (D4) and the MAP sensor- An intermiftent short in the wire between the PCM {D10) and the TP sensor.PGM-Fl main relay.'See the OBD ll scan tool or Honda PGM Tester user's manuals lor specilic operatinginstructions,
NOTE: An open or short in the wire between the PCM (C8) and the DLC will keep thescan tool or Honda PGM Tester lrom communicating with the PCM. You should ioterpretthis as no DTCS are indicated.
PCM CONNECTORc l3lPl scs .BRNI
lTo page 11 84)Wire sid6 of f€male terminalg
(cont'dl
11-83
The Malfunciion lndicator Lamo{MlL) stavs on o. comes on afteltwo seconds,
Check the Oiegnosiic TroubleCode (DTC):
1. Connect an OBD ll scan toolor Honda PGM Tester.2. Turn the ignition switch ON 1lli.3. Read the DTC with the scantool or Honda PGII Tester.
Go to troubleshooting procedures(s€€ page 11501.Are any DTCIs) indicated?
Ch6ck lh6 DTC by MIL indication:1. Turn the ignition switch OFF.2. Connect the SCS service con-nector to the service checkconnector.3. Turn the ignition switch ON (ll).
- Repair opon or short in wi.6between the PCM (C8) andData Link Connector.- Go to troubloshooting proce-
dur€s {3ee page 11-601.
Does the MIL indicate any DTc?
Try to start the engine.
Does the engine start?
Check tor a short in the wire{SCS line):1. Turn the ignition switch OFFand turn the ignition switchoN flt).2. Measure voltage between thePCM connector terminal C7and body ground.
Repair short to body ground inthe wire between PCM lCTl andservice check connector.ls there approx. 5 V?
(To page 1'l-84)
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PGM-FI System
Engine Control Module/Poweftrain Control Module (ECM/PCM) -'98 - 00 Models (cont'dl
NOTE:. When there is no Diagnostic Trouble Code IDTC) stored, the MIL will stay on iI the SCSservice connector is connected and the ignition switch is ON (ll).. lf this symptom is intermittent, check for:- An intermittent short in the wire between the ECM/PCM (A10) and the service checkconnoctor- An intermittent short in the wire between the ECM/PCM (At8l and the gaugeassemDty. See the OgD ll scan tool or Honda PGM Tester user's manuals for specific operatingrnstructions.
ECM/FCM CONNECTOF A {32P)
Wire side of femsle t6rminals
The Malfunction lndicator LamolMlll 3lays on or comes on aftertwo 3econds.
Check the Dirgnostic TroubloCod€ (DTCI:'1. Connect a scan tool or HondaPGM Tester.2. Turn the ignition switch ON (ll).3. Read the DTC with the scantool or Honda PGM Tester.
Go to troublGhooting procadura.(3€c prg€ l lS0l
check tho DTc by MIL indication:1. Turn the ignition switch OFF.2. Connect the SCS service con-nector to the service checkconnector,3. Turn the ignition switch ON (ll).
Ropair op.n ol Bhort in wirob.twe.n thc ECM/FCtrl (A21)
and D.i. Link Connoctor.Go to troublo3hootlng proc€-dur6. lt o pag. 11.6lrl
Does the MIL indicate any DTC?
Try to start the engine.
Sub3titute r known"good ECM/PCM .nd roch.ck. lt .ymptom/indic.tion gooa awsy, repl.cothe origin.l ECM/PCM.
Does the engine stan?
Check tor a 3hort in the wireISCS linel:1. Turn the ignition switch OFFand turn the ignition switchoN { ).2- Measure voltage betweenbody ground and the ECM/PCi, conneclor terminal A10.
Ropria ahort to body ground intho wi.c Mwe.n tho ECM/PCMlA10l and aarvic. check connsc-tor.
lTo page 1l-89)
11-88
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PGM-FI System
Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1)
The Heated Oxygen Sensors (HO2S) detect the oxygen content in the exhaust gas and signal the ECM/PCM. In operation,
the ECM/PCM receives the signals from the sensor and varies the duration during which fuel is iniected. To stabilize the
sensor's output, the sensor has an internal heater. The Primary HO2S (Sensor 1) is installed in exhaust pipe A.
HO2S:
ztRcoNtAEI.IMENT
s€NsoRTERMINALSVOLTAGE IVI
HEATEBTERMINALS
The scan tool indicates Diagnostic Trouble Code (DTC) P0131: A low voltage
Oxygen Sensor (HO2S) {Sensor 1} circuit,
RICH - AIR. . LEANFUELNATO
problem in the Primary Heated
37 - 98 models:
HEATER
The MIL has been reoorted on.DTC P0131 is stoied.
Problem verification:1. Do the ECM/PCM Reset Pro-ceoure.Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on.Test-drive with the A/T in Eposition (M/T in 4th gear)Check the Primary HO2S{Sensor 1} output voltage withthe scan tool during accelera-tion using wide open throttle.
Intermittent f.ilure, system is OKat this time. Check fo. poor con-nections or loose wirer at C111(Primary HO2S, SeGor 1) and atrh€ ECM/FCM.
Check the fuel pressure (see page
11-178).
Repair the fuel supply system.
{To page 11'111}
1 1-1 10
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The scan tool indicates Diagnostic Trouble Code (DTC) P0132: A high voltage problem in the Primary HeatedOxygen Sensor {Primary HO2S) (Sensor 1) circuit.
'97 - 98 models:
PHO2S
IWHTIsG2IGRN/BLK}
Wire side ot female terminals
PCM CONNECTOR D {16PI
JUMPER WIRE
PHO2S IWHTISG2 IGRN/BLK}
Wire side of temale terminals
I
(cont'dl
11-113
Problem verification:1. Do the ECM/PCM Resot Pro,ceoute,2. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on.3. Test-drive with the Ay'T in Eposition (M/T in 4th gear).4. Check the Primary H02S{Sensor 1}output voltage withthe scan tool during decelera-tion using completely closedthrottle.
Intormittent l.ilure, 3ystem ia OKat thb timo. Chcck fo. poor con-nections 01 looso wi.es at C111{Prim!ry HO2S, Sensor 1} andECM/PCM.
Does the voltage stay at 1.0 V
Check for an open in th6 PrimaryH()2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor 1) connector-3. Connect the Primary HO25lSensor 1) 4P connector termi-nals No. 1 and No. 2 with ajumper wire.4. Turn the ignition switch ON (ll).5. Check the Primary HO2S(Sensor 1) output voltage withthe scan tool,
ls there 1.0 V or more?
Ch€ck for an opon in the wires(PHO2S, SG2linesl:1. Turn the ignition switch OFF.2. Connect PCM connector ter-minals D7 and Dl1 with a
3. Turn the ignition switch ON (ll).4. Check the Primary HO2S{Sensor 1) output voltage withthe scan tool.
Roprir opon in the wire betweontho PCM {D7 01 D11l and thePrimsry HO2S {S6nsor 1).
ls there 1.0 V or more?
{'97 model}
{To page 11-114)
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PGM-FI System
Primary Heated Oxygen Sensor (Primary HO2S) lSensor 1) (cont'd)
tFO133 lhe scan tool indicates Diagnostic Trouble Code (DTC) P0133: A slow response problem in the Primary Heated: Oxysen Sensor (Primarv HO2S (Sensor 1) circuit.
Description
By controlling the airlfuel ratio with a Primary HO2S (Sensor 1) and a Secondary HO2S (Sensor 2), the deterioration of the
Primary HO2S (Sensor 1) can be evaluated by its feedback period. When the feedback period of the HO2S exceeds a cer
tain value during stable driving conditions, the sensor will be judged as deteriorated.
When deterioration has been detected during two consecutive trips, the MIL comes on and DTC P0133 will be stored.
NOTE: lf DTC P0131, P0132 and/or P0135 are stored at the same time as DTC P0133. troubleshoot those DTCS first, then
troubleshoot DTC P0133.
Possible Cause
. Primary HO2S (Sensor 1) Deterioration
. Primary HO2S Heater (Sensor 1) Deterioration
. Exhaust system leakage
Troubleshooting Flowchart
- The MIL has b6€n reoorted on.- DTC P0133 is stored.
Problem Verilication:'1. Do the ECM/PCM Reset Procedure.2. Connect the scan tool.3. Start the engine. Hold theengine at 3,000 rpm with noload lin Park or neutrali untilthe radiator fan comes on.4. Connect the SCS service connector.5. Test-drive under the followingcondations,55 mph (89 km/h) steadyspeed- M in @ position (E position and Over Drive ON)*,(M/T in sth gear)- Until readiness code comes
Intermittent failure, system is OKat this time. Check tor poor con-nections or loose wires at C111(Primary HO2S, Sensor 1) and althe ECM/PCM.
Replace the Primary HO2S {Sen-sor 11.
1 1-1 16
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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.
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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
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Emission Control System
Three Way Catalytic Converter {TWCI (cont'd}
1P0420 Thescantool indicates Diagnostic Trouble Code (DTC) P0420: Catalyst system efficiency belowthreshold.
DescriDtion
This system evaluates the catalyst's capacity by means of the HO2S (Primary and Secondary) output during stable driving
conditions. lf deterioration has been detected during three consecutive driving cycles, the MIL comes on and DTC P0420 will
be stored.
NOTE: lf some of the DTCS listed below are stored at the same time as DTC P0420, troubleshoot those DTCS first. then
troubleshoot DTC P0420.
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater
Possible Cause
. IWC Deterioration
. Exhaust system leakage
Troubleshooting Flowchart
- The MIL has been reDoried on.- DTC P0420 is stored.
Problem verification:1. Do the ECM/PCM Reset Procedure,2. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutrali untilthe radiator fan comes on.3. Connect the SCS service connector.4. Test-drive 40 - 55 mph (64 - 88km/h) for approx. lwo minutes.Then decelerate for at least 3seconds with the throftle completely closed. Then reducethe vehicle speed to 35 mph
156 km/h), and try to hold ituntil the readiness code
Intermittent tailure. system is OKat this time.ls DTC P0420 indicated?
Check the TWC (see section 9).lI nocessary, replace the TwC.
11-200
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