1997 HONDA CIVIC Check engine light is on

tAlternator (ALT) FR Signal ('99 - 00 Models except Dl6Y5 engine with M/T)
This signals the ECM/PCM when the Alternator {ALT) is chargingECM/PCM CONNECTORS
Wire side of female terminals
ECM/PCM CONNECTOR C (31P}
lt
lP
ALT CONNECTORS IClO4I
JUMPER
JUMpER WlnE
WIRE
Wire side of female termlnals
ECM/PCM CONNECTOR C (31PI
3P*NO
Check lor an op€n in the wire (ALT
F line,:1. Turn the agnition switch OFF
2. Disconnect the negative bat-
tery cable {rom the battery.
3. Disconnect the ECM/PCM con'
nector C (31P).
4. Disconnect the 4P (3P)* con'
nector from the ALT.
5. Connect the ALT 4P (3P)* con-
nector terminal No 4 (No. 1)*
to bodY ground with a iumper
6. Check lor continuity between
body ground and ECM/PCM
connector terminal C5
--?--1l2l|#i3l.l
otriJrwxrr (V)
neor Y
lnsoeclion oI ALT FB Signal.
Check {or a short in the wire {ALT
F line):1. Disconnect the 4P (3P)+ con
nector from the ALT
2. Turn the ignition switch ON (ll)
3. Measurc voltage between EcM/
PCM connector terminals C5
and 820.Check tor a short in the wirc (ALt
F line):1. Turn the ignition switch OFF
2. Disconnect the negative bat_
tery cable from the baRery'
3. Disconnect the ECM/PCM con'
nector C (31P).
4. Check for continuity between
body ground and ECM/PCM
connector terminal C5
ls there aPProx. 5 V?
Check the operation otthe ALT:
1. Turn the ignition switch OFF.
2- Reconnect the ALT 4P (3P)*
connector to the ALT
3. Start the engine. Hold the
engine at 3,000 rpm wrth no
load {in Park or neutrali until
the radiator fan comes on,
then let it idle.
4- Measure voltage between ECM/
PCM connector terminals C5
and 820.
Repair short in the wire between
the EcM/PCM {C5l and the ALT.
Substitute a known-good ECM/
PCM and rechock. lf P.esc.ibedvoltage is now availabl€, ieplace
tho original ECM/PCM
Does the voltage decrease when
headlights and rear delogger are
turned on?
ALT FF signal is OK.
Repair oPen wire betwoen t|lo
ECM,/PCM {C5) and the ALT.
ALT F (WHT/RED)
Wire side of temale terminals
*: Canada model
Wire side of female termrnals

ldle Control System
Brake Switch Signal ('96 - 98 Models, '99 - 00 Dl6YS engine with M/Tl
This signals the ECM/PCM when the brake pedal is deoressed.
LGlBKSW(GRN/WHTI
D {16P)
Wire side of female t€rminals
Inspection of Brake Switch Signal.
Are the brake lights on withoutdepressing the brake pedal?
Depress the brake pedal.
Inspect the HORN (15 A) fuse inthe under-hood fuse/ relay box.Do the brake lights come on?
- Repair short in the wirebetween the brake 3whch andrhe HORN 115 At lu3e.- Replace the I|oRN 17.5 A) tus€.
Repair open in the wirebetween the brake switch andthe HORN 115 Al fuse.Inspect th6 br.ke switch {s6€section l9l.Check tor an open in the wireIBKSW line):1. Oepress the brake pedal.2. Measure voltage betweenECM/PCNI connector terminalsAg and D5 with the brake pedaloepresseo.
Repair open in the wire b€tweenthe ECM/PCM {Dsl and the brakeswitch.
ls there battery voltage?
Brakc switch sign.l is OK.
ECM/PCM CONNECTOFS
A (32PtIBRI\v
,la678101112I
121311151617t8192022232aI9101112
25212Aa3013141516
11-210

IJBrake Switch Signal ('99 - 00 Models except Dl6Y5 engine with M/Tl
This signals the ECM/PCM when the brake pedal is depressed
I
lnsoection ot Brake Switch signal.
Are the brake lights on without
depressing the brake Pedal?
Depress the brake Pedal
Inspect the HoRN {15 A} fuse in
the underhood fuse/ relay box'Do the brake lights come on?
- R.pair short in the wiro be'
tween the brake switch and
the HORN (15 Alfuse.- Replac€ the HORN (15 A) tuse.
- Repair open in the wite be'
tween the brako switch and
the HORN (15 Alfuse.- lnsoect the brake switch (3ec
section tgl.
Check fot an oPen in the wire
{BKsw linel:
1. Depress the brake Pedal.2. Measure vohage beween ECM/
PCM connector terminals A32
and 820 with the brake Pedaldepressed.
Bepair open in the wire between
the ECM/PCM (A32) and the
brake switch.
Brake switch signal i5 OK
ECM/PCM CONNECTORS
BKSW (GRN/WHTI
LG1 {BRN/BLK)
Wire side o{ female terminals

ldle Control System
ldle Speed Setting
Inspection/Adiustmenl
'96, '97 Dl6Y5. '96 - 00 Dl5Y8 sngine with M/T
NOTE:
. Before setting the idle speed, check the following
items:- The MIL has not been reported on.- lgnition timing- Spark plugs- Air cleaner- PCV system
o (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 withno load (taansmission in neutral) until the radiatorfan comes on, then let it idle.
2. Connect a tachometer.
3. Disconnect the IAC valve connector.
4.lf the engine stalls, restart the engine with the accel-
erator pedal slightly depressed. Stabilize the rpm at1,000, then slowly release the pedal until the engineidles.
Check idling in no-load conditionsr headlights. blowerfan. rear defogger, radiator fan, and air conditioner
are not operating.
ldle spsed should be:
450 1 50 rpm
11-220
Adjust the idle speed, if necessary, by removing thecap and turning the idle adjusting screw.
NOTE; After adjusting the idle speed in this step,recheck the ignition timing (see section 23).
lf it is out of spec, go back to step 4.
IDLE
6. Turn the ignition switch OFF.
7. Reconnect the 2P connector on the IAC valve, then
do the ECM reset procedure.
8. Restart and idle the engine with no-load conditionsfor one minute, then check the idle speed.
NOTE: (Canada) Pull the parking brake lever up.Start the engine, then check that the headlights areoff.
ldle sp€sd should b€:
670 i 50 rpm IUSA)750 t 50 rpm {Canada}
9. ldle the engine tor one minute with headlights {Low)ON. and check the idle speed.
ldle speed should be:
750 :r 50 rpm
10. Turn the headlights off. ldle the engine for oneminute with heater fan switch at Hl and air conditioneron, then check the idle speed.
ldle speed should be:
810150 rpm
NOTE: lf the idle speed is not within specification,see Symptom Chan on page 11-84.

ldle Control System
ldle Speed Setting (cont'dl
Inspeqtion/Adiustment
38 D16Y5 engine whh M/T,'99 - 00 81642 engine
NOTE: Before setting the idle speed, check the follow-ing items;- The MIL has not been reported on.- lgnition timing- Spark plugs- Air cleaner- PCV system
'1. Start the engine. Hold the engine at 3,000 rpm withno load (transmission in neutral) until the radiatorfan comes on, then let it idle.
Connect a tachometer.
Disconnect the IAC valve 2P connector and the EVAPpurge controlsolenoid valve 2P connector.
EVAP PURGECONTROLSOLENOID VALVE
lf the engine stalls, restart the engine with the accel-erator pedal slightly depressed. Stabilize the rpm at1.000, then slowly release the pedal until the engineidles.
Check idling in no-load conditions: headlights, blowerfan, rear defogger, radiator fan, and air conditionerare not operating.
ldl€ speed should be:
450 i 50 rpm
11-222
lf necessary, adjust the idle speed, by removrng lnecap and turning the idle adjusting screw.After adjusting the idle speed recheck the ignitlontiming (see section 23). lf it is out of spec, go backto step 4. |DLE
6. Turn the ignition switch OFF.
7. Reconnect the 2P connectors to the IAC valve andthe EVAP purge control solenoid valve, then do theECM reset procedure.
8. Restart and idle the engine with no-load conditionsfor one minute, then check the idle sDeed.ldle speed should bo:
USA:
D16Y5 engine: 670 i 50 rpm
81642 engine: 700 i 50 rpm
Canada:
81642 engine: 750 t 50 rpm
NOTE: lf the idle speed increases to 8lO t 50 rpm,this means the EVAP system is purging the canister.To stop the purging temporarily, raise the enginespeed above 1,000 rpm with the accelerator pedal,
then slowly release the pedal.
9. ldle the engine for one minute with headlights(Low) ON. and check the idle speed.
ldle speed should be:
750 i 50 rpm
10. Turn the headlights off. ldle the engine for oneminute with heater fan switch at Hl and air condi-tioner on, then check the idle soeed.ldls speed should be:
810 t 50 rpm
lf the idle speed is not within specification, seeSymptom Chart on page 11-84.

\
I
'98 - 0O D16Y5 ongine with CvT
Adjust the idle speed using a Honda PGM Tester if pos-
sible. lf not, use the following procedure:
NOTE:
. Leave the IAC valve connected.
. Before s€tting the idle speed, check the following
rtems:- The MIL has not been reported on.
- lgnition timing
- Spark Plugs- Air clean€r
- PCV svstem
'1. Connect a tachometer.
2. Stan the engine. Hold the engine at 3,000 rpm w'th
no load (transmission in E or E] position) until the
radiator Jan comes on, then let it idle.
3. Check the idle speed under no-load conditions:
head lights, blower fan, rear defogger, radiator fan,
and air conditioner are not operatlng.
ldlo spaod ehould bo: 700 t 50 rpm
. lf the idle speed is within the specification, the
procedure is comPlete.
. lf the idle sDeed is out of specitication, 9o to step 4'
4. tf the idle speed is 810 1 50 rpm, this means the
EVAP system is purging the canister. To stop the
purging temporarily, raise the engine speed above
l,OO0 rgm with the accelsrator pedal. Slowly release
the pedal. and rscheck the idl€ speed.
. tf the idle speed is within the specificstion, the
Drocedure is comPlete.
. lf the idle sp€ed is out of spocification, go to step 5.
5. Disconnect th€ EVAP purgs control solenoid valve
2P connector.
EVAP PURGECONTROL
6. Remove the cap and turn the idle adiusting screw
1/2-turn clockwise or counterclockwlse
IDLE
7.After turning the idle adjusting screw 1/2-turn, check
the idl€ speed again. lf it is out of spec, turn the idle
adjusting screw 1/2-turn again.
NOTE: Do not turn the idle adjusting screw more
than 1/2-turn without checking the idle speed.
Turn the ignition switch OFF. Reconnect the EVAP
purge control solenoid valve 2P connector' then do
the ECM reset Procedure.
Start the engine. ldle the engine for one minute with
heater fan switch at Hl and air conditioner on, then
check the idle speed.
ldle spaed should be:
810 t 50 rpm (in El or E Posiiion)
lf the idle speed is not within specification, see
Svmptom Chart on Page 11-84.
9.
SOLENOID VALVE
11-223

Emission Gontrol System
System Description
The emission control system includes a Three Way Cata-lytic Convener (TWC), Exhaust Gas Recirculation (EGR)
system,. Positive Crankcase Ventilation (pCV) system andEvaporative Emission (EVAP) Control system. The emis-sion control system is designed to meet federal and stateemission standards.*: D16Y5 engine
Tailpipe Emission
Inspestion
@@ Do not smoke during ihis procedure. Keepany open flame away from your work area.
1. Start the engine. Hold the engine at 3,000 rpm withno load (in Park or neutral) until the radiator fancomes on. then let it idle.
2. Connect a tachometer.
Check and, if necessary, adjust the idle speed (see
page 11-220 - 223).
Warm up and calibrate the CO meter according to themeter manufacturer's instructions.
Check idle CO with the 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 areoff.
CO mete. should indicate 0.1% maximum.
NOTE: '98 Dl6Y5 engine - lf the idle speed incress-es to 8101 50 rpm, this means the EVAp system ispurging the canister. To stop the purging temporari-ly. raise the engine speed above 1,000 rpm with theaccelerator pedal, then slowly release the pedal.
11-252
eFORWARD -
Three Way Catalytic Converter
(TWCI
Doscription
The Three Way Catalytic Converter (TWC) is used toconven hydrocarbons (HC), carbon monoxide (CO), andoxides of nitrogen (NOx) in the exhaust gas to carbondioxide (COr), dinitrogen (N,) and water vapor.
D15Y5, D16
, engine:
'99 - 00 D16Y8, 81642 engine:
ENGINE SIDE
t

Emission Control System
Positive Crankcase Ventilation IPCVI System
Descripiion
The Positive Crankcase Ventilation (PCV) system is
designed to prevent blow-by gas from escaping to the
atmosphere. The PCV valve contains a spring-loaded
plunger. When the engine starts, the plunger in the PCV
valve is lifted in proportion to intake manifold vacuum
and the blow-by gas is drawn directly into the intake
manifold.
D15Y5, D16Y8, 816A2 ongins:
BREATHERHOSE
Dl6'|11 6ngin6:
-: aLOW-BY VAPOR-: FnESH AIF
11-266
tJ
lrcpection
1. Check the PCV hoses and connections for leaks and
clogging.
2. At idle, make sure there is a clicking sound from the
PCV valve when the hose between the PCV valve
and the intake manifold is lightly pinched with your
fingers or pliers,
D16Y5, D16Y8 ongins:
BREATHERHOSE
PCV VALVE
Gently pinch here.
Bl6A2 engins:VALVE
lf there is no clicking sound, check the PCV valve
grommet for cracks and damage. If the grommet is
OK, replace the PCV valve and recheck.
PCV