VTEC
Ref€r to page 11-32 thru I l-39 beforo troubleshooting.
-g: -mi !5*3ij'i:,*o:",,XTl.Lamp
(MlL) indicates Disenostic rrouble code (Drc) 2r:A problem in the wEc
\,__-:-/ \.---l-l
Iel- -l 2,1 l-
MIL h.. b..n Fport d on.Wrth aaavica chack connac,tot
iomp.d, Codc 2l i. indic.t.d.
Oo tho ongino control module(ECM) Rg3ot Procgduro.
w6rrn up engine to normal op€r-ating tsmporature (the coolingfan comog on).
Do th€ Road Test.'
lmormitt.m t ilur., .yrtom i. OK!t thi.tim..Chacl tor poor connactiont otloo.. wircr !l VTEC .ol.noidv.lv. lnd ECM.
ls MIL on and does it indi-cato cod€ 21?
Turn tho ignition switch OFF.
Oisconnect tho 1P connsctorlrom the VTEC solenoid valvo.
Chock for continuity betw66n 1Pconn6clor terminal and body
9rcUnO.
ls there '14 - 30 07R.pl.c. th. VTEC rolonoid v.lvr,
' Road Test:Accelerate in 1st gear to 6n engino spood ovor 6000 rpm.Hold thst engine sp€ed tor at least two seconds.lflhe MIL do6s not coms on during th€ first road tost,reoeat this test two more tim95.
YES
(To pago G37l
6-36
wEc
6-38
Troubleshooting Flowchart - VTEC Pressure Switch
Refer to page 11-32thru 11-39 beJore troubleshooting'
-.+- -r";-r- Malfunction Indicator Lamp (MlL) indicates Oiagnostic Troubles Code (DTC) 22: A problem in the VTEC- l{{?l- ;l ziz r: pressur€ Switch circuit.
-lr@l- |22 1-
* Road Test:Accolerato in lst gear to an engine speed over 6000 rpm
Hold that engine speed for at least two seconos'
lf the MIL does not come on during the first road test'
reoeat this test two more limes.
- MIL har bagn.oportcd on.- With t.rvic. chack connactor
iump.d, cod€ 22 it indic.t.d.
Do the engine control module(ECM)Reset Procedure.
Warm !p engine to normal oper-
ating temperstur€ (cooling fan
comes on).
Do the Boad T€st.'
Intc.mift.nt failu.o, ry3tom ia OK
at thi. tim..Chack for pool connaction3 ol
loo!. rvirat at VTEC Ptasturo3whch and ECM.
ls MIL on and does it indi'
cate code 22?
Turn lhe ignition switch OFF
Disconnect the 2P connector
lrom the VTEC Pressure switch.
Check Ior continuity between
BLK terminal and body ground.
Rcpair opcn in BLK wit. botwcon
2P connector rnd body ground
tG101l.
Check for continuity between
8LU/8LK terminal and D6 termi'
nal.
(To page 6 39)
Troubleshooting
Troubleshooting Guide
NOTE: Across each row in the chart. the systems that could be sources of a symptom are ranked in the order they should
be inspected staning with O. Find the symptom in the left column, read across to the most likely source. then refer
to the page listed at the top of that column. lf inspection shows the system is OK, try the next mosr likely system O, etc,
* lf codes other then those listed above are indicated, count the number of blinks again. It the MIL is in fact blinking
^ these codes, replace the ECM.
qy, lf the MIL is on while the engine is running. connect the SCS shon connector to the service check connector. It no
code is displayed {MlL stays on steady), the back-up system is in operation.
Substitute a known-good ECM and recheck. lf the indication goes away, replace the original ECM.
USA:
MALFUNCTION
INDICATOR
LAMP {MIL)
CANADA: ----l CHECK-ltGl- ENGTNE- | - LTGHT
- { -1t-
* * *: 818C1 engine
1-32
SYMPTOM
PGM.FI
ENGINECONTROLMOOULE
HEATEOOXYGENSENSOR
MANIFOLOAESOLUTEPRESSURESENSOR
TOP DEAD CINTTR/CRANKSHAFTPOSTT|ON/CYLINDERPOSITION SENSOR
ENGINECOOLANTTEMPfRA.TURTSENSOR
THROTTTEPOStTtONSENSOR
INfAKE AIRTEMP€RA.TUREsar,rs0R
BARO.METRICPRESSURESENSOR
IGNITIONOUTPUTSIGNAL
vEHtct-ESPfEDSENSOR
11.4246, 47,5011-56l1-581l-6011-6211-641t-661r-68
MALFUNCTION INOICATORLAMP (MIU" TURNS ON1 lor:t:]:lrmr:- i;:i'-tK3t-16l-16l'-\-16l/-----\
-r:+r-
-{"Pr:-o_-16l-.z-\r6t/_-\
MALFUNCTION INOICATORLAMP (MIL)'' BLINKS:O. or-8.-D:o.:@.
o, O'l3l/__-\.E-o.:O: or tr]--i !l/ -i-\| 7 t-/__-\
--l-l-l r0 I/----\| 13 |z_---\
\.--r--l
I r5 t-/.---\-t 17 t-/-]-\
ENGINE WON'T STAffTo@@
DIFFICULT TO STARTENGIN€ WHEN COLO@@(9)o
IRREGULARIDLING
WHEN COTDFAST IDLEouT 0f sPtc@@
ROUGH IDLE@o
RPM TOOHIGH@@
RPM TOOLOW@
FREOUENTSTALLING
WHILE@@
AFTER@
POOnPERFOEM.ANCE
MISFIRE ORROUGHRUNNING@@@
FAITSEMISSIONTEST@@@
Loss 0FPOWER@@@
Troubleshooting
Self-diagnostic Procedures
When the Malfunction Indicator Lamp {MlL) has been reported on, do the following:
'1. Connect the SCS short connecto. to Service Check Connector as shown. (The 2P Service Check Connector is
located under the dash on the passenger side of the car.) Turn the ignition switch on.
DATA LII{KCONNECTOR (3PI
NOTE:Do not attachjumper wire.
2. Note the Diagnostic Trouble Code (DTC): The MIL indicates I code by the length 8nd numbsr ot blinks. The MIL
can indicate multiple component problems by blinking separate codes, one after another. Codes 1 through Igre
indicated by individual shon blinks. Codes 1O through 43 are indicated by a series of long and shon blinks. Th€
number of long blinks equals the first digit, the number ot short blinks equals the second digit. Sometimes the
firsr blink is difficult to see; always count the blinks at least twice to verify the code.
MALFUNCTIOI{INDICATORLAMP
CANADA:CHECKENGINELIGHTIMIL}
Sgprrate Prcbaomr:shT
-n-----n- =n- = s.o DTc 1
+!+1].TL;I!!=- = s.. Drc 3-L ,JU '" " " = Sce DTC 13
Long .hon
Multiplr Probl.ln.:
J-l_tx-TL-n-ffu-r- = S€. DTC 1 lnd 3-J.rrU-L-r]tltlr'l- __-tnrua = Sce DTC 3 and 4Jll-lrl-t-----Tt/'tnj]_ = S.. DTC 3 lnd 14
11-34
Troubleshooting
Self-diagnostic Procedures (cont'dl
':818C1 engine
a lf codes other than those listed above are indicated, verifv the code. lf the code indicated is not listed above, replace
rhe ECM.
a The MIL may come on, indicating a system problem when, in fact, there is a poor or intermittent electricalconnection.
First, check the electrical connections, clean or repair connections it necessary.
o The MIL and @ indicator light may light simultaneously when the Diagnostic Trouble Code (DTC) 6, 7 or 17. Check
the PGM-Fl system according to the PGM-Fl system troubleshooting, then recheck the l!! indicator light. ll it lights,
see page 14-5O, 51.
a The MIL does not come on when there is a malfunction in the A/T Fl signal or Electrical Load Detector (ELDI circuits.
However, it will indicate the codes when the Service Check Connector is shorted.
DIAGNOSTIC
TROUBLE
CODE (DTCISYSTEM INDICATEDPsge
oENGINE CONTROL MODULE IECM)11-42
,lHEATED OXYGEN SENSOR IHO25)1 1-46
aMANIFOLD ABSOLUTE PRESSURE {MAP SENSOR)11-52
4CRANKSHAFT POSITION (CKP SENSOR)1 1-56
oENGINE COOLANT TEMPERATURE (ECT SENSOR)11-58
THROTTLE POSITION (TP SENSOR}11-60
ITOP DEAD CENTER POSITION (TDC SENSORI1 1-56
9No. 1 CYLINDER POSITION (CYP SENSOR)1 1-56
10INTAKE AIR TEMPERATURE (IAT SENSOR)11-62
13BAROMETRIC PRESSURE (BARO SENSOR}1|-64
14IDLE AIR CONTROL (IAC VALVE}11-42
tcIGNITION OUTPUT SIGNAL11-66
toFUEL INJECTOR1't-102
17VEHICLE SPEED SENSOR {VSSI11-68
20ELECTRICAT LOAD DETECTOR (ELD)'t 1-70
21VARIABLE VALVE TIMING & VALVE LIFT ELECTRONIC CONTROL SOLENOID
VALVE {VTEC SOLENOID VALVE)'6-36
22VARIABLE VALVE TIMING & VALVE LIFT ELECTRONIC CONTROL PRESSURE
SWITCH (VTEC PRESSURE SWITCHI-6-38
23KNOCK SENSOR {KS}-11-7 4
30A/T FI SIGNAL A11-76
3'rA/T FI SIGNAL B1 1-76
4'lHEATED OXYGEN SENSOR (HO25} HEATER11-47
43FUEL SUPPLY SYSTEM1 1-50
11-36
3. Fuel Cut-oft Control
a During deceleration with the throttle valve closed, current to the {uel injectors is cut otJ to improve fuel economy
at speeds over tollowing rpm:
. 8188l engine: 91O tpm (Canada model: 1,O50 rpm)
. 818C1 engine: 95O tpm (Canada model: l,O5O rpm)
a Fuel cut-olf action also takes place when engine speed exceeds, 7,O0O rpm {81 8B1 engine), 8,1O0 rpm (B 18Cl
engine), regardless oI the position of the throttle valve, to protect the engine from ovet-revving.
A/C Compressor Clutch Relay
When the ECM receives a domand for cooling trom the air conditioning system, it del8ys the compressor from being
enetgized, and enriches the mixture to assure smooth transition to the A/C mode.
Evaporative Emission (EVAP) Purge Control Solenoid Valve
When the engine coolant tempersture is below 163oF {73"C), the ECM supplies a ground to the EVAP pu.ge control
solenoid valve which cuts vacuum to the EVAP purge control diaphragm valve.
Intake Air Bypsss (lAB) Control Sol€noid Valve
When the engine rpm is below 5,750 rpm, the IAB control solenoid valve is activated by a signal from the ECM,
intske air flows through the long intake path, then high torque is delivered. At spaeds highe. than 5,750 rpm, the
solenoid valve is deactivated by the ECM, and intake air flows through the short intake path in order to reduce the
resistance in airflow.
ECM fail-safe/bEck-up Functions
1. Fail-sate Function
When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-progtammed
value tor that sensor that allows the engine to continue to run.
Back-uD Function
When an abnormalitv occurs in the ECM itself, the fuel iniectors are controlled by a back-up citcuit independent of
the system in order to permit minimal driving.
Self-diagnosis Function IMaltunction Indicator Lamp {MlL)1
Wh6n an abnormality occurs in a signal from a sensor, the ECM supplies ground for the MIL and stores the code
in erasable memory. When the ignition is initially turned on, the ECM supplies ground tor the MIL tor two seconds
to check the MIL bulb condition.
Two Trio Detection Method
To prevent tals€ indications, th€ Two Trip Dstection Method is used for the HO2S and fuel metering-related self-
diagnostic tunctions. When an abnormslity occurs, the ECM stores it in its memo.y. Wh€n the ssme sbnormality
recurs alter the ignition switch is turned OFF and ON ag8in, the ECM informs the driver by lighting the MlL.
However, to ease troubleshooting, this function is canc€ll€d when you short the service check connector. The MIL
will then blink immedistelv when an abnormality occurs.
4.
6.
2
4.
11-41
Th. ll.lfunction Indicltor Lamp
lMlll at!y3 on o. cornaa on alt6ltwo aacond!.
Connect the SCS short connectorto th6 sorvice check connector(see page 11-34).
Turn the ignition switch ON.
Go to iolfdiagnostic Proceduros(se€ pago 11-34).Does the MIL indicate anv Oi-agnostic Trouble Code (DTC)?
Romove th€ SCS shon connectorlrom the service ch€ck connector.
Turn the ignition switch OFF.
Try to start the engine.
Connect the test harness betweenthe ECM and connectors (see
page 11-37).
Turn the ignition switch ON.
Measure voltage botween D4 (+ )terminal and D22 { - ) terminal.
connect the SCS shonconnector to servlcecheck connector.ls there approx. 5 V?
Ropair shon to body g.ound inBRN/WHT wire betwoon th6 ECMlD4) end sorvlco chock connocto?.Measure voltage be_tween D4 {+} terminaland body ground.
- R6pair open in BRN/WHT witobotwoon EcM lD4) and s6rv-ice chock connactor.- Repoir opon in BLK wiro bo-twoon 36rvi@ chock connectoaand G4Ol.
ls there approx. 5 V?
InsDoct ECU {ECM) 115 A) tuse inth6 undeFhood luse/relav box.
- Rsolaco ECU {ECM} (15 Allus€.- R6pair shon in YEL/WHT wilobotw6on ECU lEcMl 115 A)fuso and PGM-FI main rolay.
Remove the scs shortConnector from theservice check con-nector.
ls the luss OK?
NOTE:
a When there is no code stored, the MIL willstay on if the service check con-
nector is shorted.
a tf this svmotom is intermittent, check for:
- A loose ECM fuse (15A) in the under-hood tuse/relay box
- A loose No. 24 fuse (ACG) (ALT) ( 1 5A: B1 8B 1 engine, 2OA: B18C 1 en-
gine) in the under-dash fuse/relay box- An intermittent short in the BRN/WHT wire between the ECM (D4) and
the service check connector- An intermittent oDen in the BLK wire between the service check con-
nector and G4O1- An intermittent shon in the GRN/ORN wire between the ECM (A 13) and
the gauge assembly.- An intermittent short in the YELMHT wire between the ECM (D19) and
the MAP sensor- An intermittent short in the YEL/BLU wire between the ECM (D20) and
the TP sensor
o ooooo ooo ooo o loooooooo liii:$A$.Ps,l o oo ooo ooooo
o oooo ooo o o ooo I oooooooooooooooooo
D4 (+)
l"oo,o'.
D22 t-l
uu,l
'NOTE: After repair, disconnect the SCS ShortConnsctor, test drive the car, and recheckthe MIL
lor a code.
(cont'd)
(To page 1 'l -44)lTo page 1 1-44)
11-43
mll )ffltl The Malfunction Indicator Lamp (MlL) indicates Diagnostic Trouble Code (DTCI 41: A problem in
Y- -:- the Heated Oxygen Sensor {HO2S) Heater circuit.
-.----r- \- l-l
tt(gt- -t tt I-r---7r
DIGITAL MULTIMETEBCommorcially availablo orKS-AHM-32-OO3
- Th6 MIL has boen roponod on.- With the SCS rhort connoc-to. connociod (aoe pago
11-341. codo 41 is indic.tod.
Do the ECM Reset Procedure {seepage 11-351.
Intoamittont tdl||.g, ryr-t m i3 OK at thi! timo(tost driv6 lnay bg ns-cearatYl.Chock tor poor conn6c-tions or looro wires atC223 llocatod at rightshod( row..l, C3O5 {lo-cated 6t loft ahock low-or), C424, C113(HO2S) and ECM.
ls the MIL on and does it indi-cste code 41?
Turn the ignition switch OFF.
Measurc tasistance betwgen ter-minals 3 snd 4 on the HO2S.
ls thero 1O-4O 0?
t€rminal side
(To page 1 1-481
(cont'd)