1995 ACURA TL light

TWC/WU-TWC
Inspection
1. Usin g a flashlight , mak e a visua l chec k fo r plugging ,
meltin g o r crackin g o f th e catalyst .
TWC:
WU-TWC :
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CAUTION:

• Puncturing the insulation on a wire can cause poor or intermittent electrical connections.

• Bring the tester probe into contact with the terminal from the connector side of wire harness connectors in the engine

compartment. For female connectors, just touch lightly with the tester probe and do not insert the probe.

RUBBER SEAL
TESTER PROBE

WIRE HARNESS

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4. A/ C Compresso r Clutc h Rela y
When th e EC M receive s a deman d fo r coolin g fro m th e ai r conditionin g system , i t delay s th e compresso r fro m bein g
energized , an d enriche s th e mixtur e to assur e smoot h transitio n to th e A/ C mode .
5 . Evaporativ e Emissio n (EVAP ) Purg e Contro l Solenoi d Valv e
Whe n th e engin e coolan t temperatur e i s belo w 167° F (75°C ) ('9 7 - 9 8 models : 158° F (70°C) , th e EC M control s th e
EVA P purg e contro l solenoi d valv e whic h cut s vacuu m to th e EVA P purg e contro l caniste r diaphragm .
6 . Intak e Ai r Bypas s (IAB ) Contro l Solenoi d Valv e
Whe n th e engin e spee d i s belo w 4,80 0 rpm , th e IA B contro l solenoi d valv e i s activate d b y a signa l fro m th e ECM ,
intak e ai r flow s throug h th e smalle r chamber , the n hig h torqu e i s delivered. At speed s highe r tha n 4,80 0 rpm , th e
solenoi d valv e i s deactivate d b y th e ECM , an d intak e ai r flow s throug h th e large r chambe r i n orde r t o reduc e th e
resistanc e in airflow .
7 . Exhaus t Ga s Recirculatio n (EGR ) Contro l Solenoi d Valv e
Whe n th e EG R is require d fo r contro l o f oxide s o f nitroge n (NOx ) emissions , th e EC M control s th e EG R contro l
solenoi d valv e whic h supplie s regulate d vacuu m to th e EG R valve .
8 . Alternato r Contro l
Th e syste m control s th e voltag e generate d a t th e alternato r i n accordanc e wit h th e electrica l loa d an d drivin g mode ,
whic h reduce s th e engin e loa d to improv e th e fue l economy .
ECM Fail-safe/Back-u p Function s
1. Fail-saf e Functio n
Whe n a n abnormalit y occur s in a signa l fro m a sensor , th e EC M ignore s tha t signa l an d assume s a pre-programme d
valu e fo r tha t senso r tha t allow s th e engin e to continu e to run .
2 . Back-u p Functio n
Whe n a n abnormalit y occur s in th e EC M itself , th e fue l injector s ar e controlle d b y a back-u p circui t independen t o f th e
syste m in orde r t o permi t minima l driving .
3 . Self-diagnosi s Functio n [Malfunctio n Indicato r Lam p (MIL) ]
Whe n a n abnormalit y occur s i n a signa l fro m a sensor , th e EC M supplie s groun d fo r th e MI L an d store s th e DT C in
erasable memory . Whe n th e ignitio n i s initiall y turne d on , th e EC M supplie s ground for th e MI L fo r tw o second s t o
chec k th e MI L bul b condition .
4 . Tw o Tri p Detectio n Metho d ('9 5 - 9 6 models )
T o preven t fals e indications , th e Tw o Tri p Detectio n Metho d is use d fo r th e MA F sensor , H02S , fue l metering-related ,
idl e contro l system , EC T sensor , an d EG R syste m self-diagnosti c functions . Whe n a n abnormalit y occurs , th e EC M
store s i t i n it s memory . Whe n th e sam e abnormalit y recur s afte r th e ignitio n switc h i s turne d OF F an d O N (II ) again ,
th e EC M inform s th e drive r b y lightin g th e MIL .
However ,
to eas e troubleshooting , thi s functio n is cancelle d when you shor t the servic e check connector . The MI L will
the n blin k immediatel y whe n a n abnormalit y occurs .
5 . Tw o (o r Three ) Drivin g Cycl e Detectio n Metho d ('9 5 - 9 6 models )
A "Drivin g Cycle " consist s o f startin g th e engine , beginnin g close d loo p operation , an d stoppin g th e engine . I f misfir -
in g tha t increase s emission s o r EVA P contro l syste m malfunctio n i s detecte d i n tw o consecutiv e drivin g cycles , o r
TW C deterioratio n is detecte d in thre e consecutiv e drivin g cycles , th e EC M turn s th e MI L on .
However , t o eas e troubleshooting , thi s functio n is cancelle d whe n yo u shor t th e servic e chec k connector . Th e MI L wil l
the n blin k immediatel y whe n a n abnormalit y occurs .
6 . Tw o Drivin g Cycl e Detectio n Metho d ('9 7 - 9 8 models )
T o preven t fals e indications , th e "tw o drivin g cycl e detectio n method " i s use d fo r th e H02S , fue l metering-related ,
idl e contro l system , EC T sensor , EG R system , TW C an d EVA P contro l syste m an d othe r self-diagnosti c functions .
Whe n a n abnormalit y occurs , th e EC M store s i t i n it s memory . Whe n th e sam e abnormalit y recur s afte r switc h i s
turne d OF F an d O N (II ) again , th e EC M inform s th e drive r b y turnin g o n th e MIL .
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PGM-FI System

Engine Control Module (ECM)

Is the low oil pressure light on?

Try to start the engine.

Does the engine start?

Check for an open in the wire or

bulb (MIL line):

1. Turn the ignition switch OFF.

2. Connect the ECM connector ter-

minal A7 to body ground with a

jumper wire.

3. Turn the ignition switch ON (II).
NOTE: If this symptom is intermittent, check for a loose fuse No. 1 (BACK UP

LIGHTS, METER LIGHTS, 10 A) in the under-dash fuse/relay box, a poor con-

nection at ECM terminal A7, or an intermittent open in the GRN/RED wire

between the ECM (A7) and the gauge assembly.

Is the MIL on?

Substitute a known-good ECM

and recheck. If symptom/indica-

tion goes away, replace the origi-

nal
ECM.
— Repair short in the wire

between NO. 1 (BACK-UP

LIGHTS, METER LIGHTS) (10

A) fuse and gauge assembly.

— Replace No. 1 (BACK-UP

LIGHTS, METER LIGHTS) (10 A)

fuse.

Check for an open in the wires

(PG1, PG2 lines):

1. Turn the ignition switch ON (II).

2. Measure voltage between

body ground and ECM con-

nector terminals A12 and A25

individually.

Is there less than 1.0 V?

Repair open in the wires

between ECM (A7) and gauge

assembly.

Replace the MIL bulb.
ECM CONNECTOR A (26P)

Wire side of female terminals

Repair open in the wire(s)

between ECM and G101 (located

at left side of engine) that had

more than 1.0 V.

ECM CONNECTOR A (26P)

Wire side of female terminals
The Malfunction Indicator Lamp

(MIL) never comes on (even for

two seconds) after ignition is

turned on.

Turn the ignition switch ON (II).

JUMPER WIREProCarManuals.com

Idle Contro l Syste m
Alternato r (ALT ) F R Signa l
This signal s th e EC M whe n th e Alternato r (ALT ) i s charging .
Is ther e approx . 5 V ?
Chec k th e operatio n o f th e ALT :
1 . Tur n th e ignitio n switc h OFF .
2 . Reconnec t th e AL T GR N 4 P
connecto r t o th e ALT .
3 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n o
loa d (transmissio n in o r
position ) unti l th e radiato r fa n
come s on , the n le t i t idle .
4 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d A26 .
Doe s th e voltag e decreas e whe n
headlight s an d rea r defogge r ar e
turne d on ?
Chec k fo r a n ope n in th e wir e (AL T
F line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e negativ e bat -
ter y cabl e fro m th e battery .
3 . Disconnec t th e EC M connec -
tor D (22P) .4. Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
5 . Connec t th e AL T 4 P connecto r
termina l No . 4 to bod y groun d
with a jumpe r wire .6. Chec k fo r continuit y betwee nbody groun d an d EC M con -necto r termina l D5 .
I s ther e continuity ?
Se e th e AL T inspectio n (se e
sectio n 23 ). EC
M CONNECTOR S
A (26P)D (22P)
Wire sid e o f femal e terminal s
D (22P)
Repai r shor t i n th e wir e betwee nthe EC M (D5 ) and th e ALT .
ALT F R signa l i s OK .
ALT GR N 4P CONNECTO R (C127 )
JUMPE R WIR E
Wir e sid e o f femal e terminal s
Repai r ope n wir e betwee n th e
ECM (D5 ) and th e ALT .
ECM CONNECTO R D (22P )
Wir e sid e o f femal e terminal s
Substitut
e a known-goo d EC M
an d recheck . I f prescribe d voltag e
i s no w available , replac e th e origi -
nal ECM .
Is ther e continuity ?
Chec
k fo r a shor t i n th e wir e (AL T
F line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e negativ e bat -
ter y cabl e fro m th e battery .
3 . Disconnec t th e EC M connecto r
D (22P) .4. Chec k fo r continuit y betwee n
bod y groun d an d EC M con -
necto r termina l D5 .
Chec
k fo r a shor t i n th e wir e (AL T
F line) :
1 . Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
2 . Tur n th e ignitio n switc h O N (II) .
3 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d A26 .
Inspectio
n o f AL T F R Signal .
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Brake Switc h Signa l
This signal s th e EC M whe n th e brak e peda l i s depressed .
Inspection o f Brak e Switc h Signal .
Are th e brak e light s o n withou tdepressin g th e brak e pedal ?Inspec t th e brak e switc h (se e sectio n 19 ).
Depres s th e brak e pedal .
D o th e brak e light s com e on ?
Is th e fus e OK ?
Chec k fo r a n ope n i n th e wir e(BKS W line) :
1 . Depres s th e brak e pedal .
2 . Measur e voltag e betwee n EC M
connecto r terminal s D1 2 an d
A26 wit h th e brak e peda l de -pressed . Repai
r shor t i n th e wir e be -
twee n th e brak e switc h an d
th e STO P HOR N (2 0 A ) fuse .
Replac e th e STO P HOR N (2 0 A )
fuse .
ECM CONNECTOR S
A (26P)D (22P )
Wire sid e o f femal e terminal s
Is ther e batter y voltage ? Repai
r ope n i n th e wir e betwee n
th e EC M (D12 ) an d th e brak e
switch .
Brak e switc h signa l i s OK . Repai
r ope n i n th e wire be-
twee n th e brak e switc h an d
th e STO P HOR N (2 0 A ) fuse .
Inspec t th e brak e switc h (se e
sectio n 19 ).
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Idle Spee d Settin g
Inspection/Adjustmen t
NOTE:
• Befor e settin g th e idl e speed , chec k th e followin g
items:
— Th e MI L ha s no t bee n reporte d on .
— Ignitio n timin g
— Spar k plug s
— Ai r cleane r
— PC V syste m
• (Canada ) Pul l th e parkin g brak e leve r up . Star t th e
engine , the n chec k tha t th e headlight s ar e off .
1 . Star t th e engine . Hol d th e engine at 3,00 0 rp m wit h
no loa d (transmissio n i n o r position ) unti l th e
radiato r fa n come s on , the n le t i t idle .
2 . Connec t a tachometer .
3 . Disconnec t th e IA C valv e connector .
IAC VALV E
4.
5.
Star t th e engin e wit h th e accelerato r peda l slightl y
depressed . Stabiliz e th e rp m a t 1,000 , the n slowl y
releas e th e peda l unti l th e engin e idles .
Check idlin g in no-loa d conditions : headlights , blow -
er fan , rea r defogger , radiato r fan , an d ai r conditione r
ar e no t operating .
Idl e spee d shoul d be :
550 ± 5 0 rp m
(in o r position )
Adjust th e idl e speed , i f necessary, by turnin g th e
idl e adjustin g screw .
NOTE : Afte r adjustin g th e idl e spee d i n thi s step ,
rechec k th e ignitio n timin g (se e sectio n 23 ).
I f i t i s ou t o f spec , g o bac k t o ste p 4 .
IDL E ADJUSTIN G SCRE W
6. Tur n th e ignitio n switc h OFF .
7 . Reconnec t th e 2 P connecto r o n th e IA C valve , the n
d o th e EC M rese t procedure .
8 . Restar t an d idl e th e engine with no-loa d condition s
fo r on e minute , the n chec k th e idl e speed .
NOTE : (Canada ) Pul l th e parkin g brak e leve r up .
Star t th e engine , the n chec k tha t th e headlight s ar e
off.
Idle spee d shoul d be :
700 ± 5 0 rp m
(in o r position )
9 . Idl e th e engin e fo r on e minut e wit h headlight s (Low )
O N an d chec k th e idl e speed .
Idl e spee d shoul d be :
770 ± 5 0 rp m
(in o r position )
10 . Tur n th e headlight s off .
Idl e th e engin e fo r on e minut e wit h heate r fa n switc h
a t H I an d ai r conditione r on , the n chec k th e idl e speed .
Idl e spee d shoul d be :
770 ± 5 0 rp m
(in o r position )
NOTE : I f th e idl e spee d i s no t withi n specification ,
se e Sympto m Char t o n pag e 11-36 .
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Intake Ai r Syste m
Throttl e Bod y
Descriptio n
The throttl e bod y i s a single-barre l side-draf t type . Th e
lowe r portio n o f th e throttl e valv e i s heate d b y engin e
coolan t fro m th e cylinde r head . Th e idl e adjustin g screw ,
whic h increases/decrease s bypas s air , an d th e Evaporativ e
Emissio n (EVAP ) Contro l Caniste r por t ar e locate d o n th e
to p o f th e throttl e bod y ('9 5 - '9 6 model s only) .
THROTTL E
POSITIO N
(TP)SENSO R IDL
E ADJUSTIN G
SCREW
THROTTL EVALVE
THROTTL ESTOPSCRE W(non-adjustable )
Inspection
1.
2 .
Disconnec t th e vacuu m hos e fro m th e to p of the
throttl e body ; connec t a vacuu m gaug e t o th e throt -
tle body. *
Start th e engine . Hol d th e engin e a t 3,00 0 rp m wit h
no loa d (transmissio n in o r position ) unti l th e
radiato r fa n come s on , the n le t i t idle. *
VACUU MPUMP/GAUGE , 0-3 0 in.H gA973 X - 04 1 - XXXX X
3. Allo w th e engin e t o idle , an d chec k tha t th e gaug e
indicate s n o vacuum. *
I f ther e i s vacuum , chec k th e throttl e cabl e (se e
pag e 11-137 ).
4 . Chec k tha t vacuu m is indicate d o n th e gaug e whe n
the throttl e is opene d slightl y fro m idle. *
If th e gaug e indicate s n o vacuum , chec k th e throttl e
bod y port . I f th e throttl e bod y por t i s clogged , clea n i t
wit h carbureto r cleaner .
5 . Sto p th e engine , an d chec k tha t th e throttl e cabl e
operates smoothly withou t bindin g o r sticking .
If ther e ar e an y abnormalitie s chec k for :
• Excessiv e wea r o r pla y i n th e throttl e valv e shaft .
• Stick y o r bindin g throttl e leve r a t th e full y close d
position .
• Clearanc e betwee n throttl e sto p scre w an d throt -
tl e leve r a t th e full y close d position .
* : '95-9 6 model s onl y
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