ACURA RL KA9 1996 Service Repair Manual

The scan tool indicates Diagnostic Trouble Code (DTC) P0420: Insufficient flow in the Exhaust Gas Recirculation

(EGR)
system.

Description

Deterioration (clogging, leakage, etc.) in the EGR line or EGR valve is detected by means of the changes in manifold abso-

lute pressure before and after the operation of the EGR valve.

If deterioration has been detected during two consecutive driving cycles, the MIL will come on and DTC P0401 will be

stored.

Possible Causes

• Clogging, leakage in the EGR line

• Faulty EGR valve

Troubleshooting Flowchart

Is DTC P0401 indicated?
Intermittent failure, system is OK

at this time.

YES

Clean the intake manifold EGR

port and EGR passage with car-

buretor cleaner.

Clean the passage inside the

EGR valve with carburetor

cleaner or replace the valve.
NO
Problem verification:

1. Do the PCM Reset Procedure.

2. Connect the ACS service con-

nector.

3. Test-drive under the following

conditions.

— Without any electrical load

— Transmission in posi-

tion

— Decelerate from 55 mph

(88 km/h) for at least 5 sec-

onds.
The MIL has been reported on.

DTC P0401 is stored.ProCarManuals.com

Emission Contro l Syste m
Exhaus t Ga s Recirculatio n (EGR ) Syste m (cont'd )
The sca n tool indicate s Diagnosti c Trouble Code (DTC ) P1491 : An insufficien t lift of th e Exhaus t Gas Recirculatio n
(EGR) valve .
Is DT C P149 1 indicated ?
YES
Chec k fo r vacuu m to th e EG Rvalve :1. Disconnec t th e No . 1 1 hos e fro m
th e EG R valve .
2 . Connec t vacuu m pump/gaug e
t o th e hose .
3 . Star t th e engin e an d le t i t idle .
I s ther e an y vacuum ?
YES
Chec k fo r a malfunctio n i n th e
EG R valv e vacuu m contro l
solenoi d valve :
1 . Disconnec t th e contro l bo x 4 P
connector .
2 . Rechec k th e No . 1 1 hos e fo r
vacuum .
(T o pag e 11-169 )
Intermitten t failure , syste m is O Kat thi s time . Chec k fo r poo r con -
nection s o r loos e wire s a t C251 ,
C25 4 (locate d a t lef t shoc k tower) ,
C107 (EG R valve ) an d PCM .
NOVACUU M PUMP/GAUGE , 0 - 3 0 in.H g
A973 X - 04 1 - XXXX X
No. 1 1 VACUU M
HOSE
(To pag e 11-169 )
EGRVALV E
NO
Proble m verification :
1 . D o th e PC M Rese t Procedure .
2 . Connec t th e SC S servic e con -
nector .
3. Star t th e engine . Hol d th eengin e a t 3,00 0 rp m wit h n o
loa d (i n Par k o r neutral ) unti l
th e radiato r fa n come s on .
4 . Driv e th e vehicl e o n th e roa d fo r
approx . 1 0 minutes . Tr y to kee p
th e engin e spee d i n th e 1,70 0 -
2,50 0 rp m range .
Th
e MI L ha s bee n reporte d on .
DT C P149 1 is stored .
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(From pag e 11-168 )
I s ther e an y vacuum ?
NO
Chec k fo r a shor t i n th e wir e (E S
line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e PC M connec -
tor A (26P) .3. Chec k fo r continuit y betwee n
bod y groun d an d th e contro l
bo x 4 P connecto r termina l No . 2 .
Is ther e continuity ?
NO
Substitut e a known-goo d PC M
an d rechec k (se e pag e 11-42 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , re -
plac e th e origina l PCM .
(Fro m pag e 11-168 )
Chec k fo r a malfunctio n i n th e
EG R valve :1. Mov e th e vacuu m pump/gaug e
t o th e EG R valve .
2. Wit h th e engin e a t idle , appl y26.7 kP a (20 0 mmHg , 8. 0 in.Hg )
o f vacuu m to th e EG R valve .
Doe s th e engin e stal l o r ru n
roug h an d doe s th e EG R valv e
hol d vacuum ?
YES
Chec k fo r a n ope n i n th e wir e
(VCC 2 line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EG R valv e
positio n senso r 3 P connector .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n th e
EG R valv e positio n senso r 3 P
connecto r terminal s No . 1 an d
No. 3 .
Is ther e approx . 5 V ?
NO
(T o pag e 11-170 ) Chec
k vacuu m hos e routin g o f
th e entir e EG R system . I f hos e
routin g i s OK , replac e th e EG R
valv e vacuu m contro l solenoi d
valve.
CONTRO L BO X 4P CONNECTO R (C257 )
Wir e sid e o f femal e terminal s
Repai r shor t i n th e wir e betwee n
PC M (A6 ) an d EG R valv e vacuu m
contro l solenoi d valve .
VACUU M
PUMP/GAUGE ,
0 - 3 0 in.H g
A973 X - 04 1 -
XXXX X
Replac e th e EG R valve .
EGRVALV E
No. 1 1VACUU M
HOS E
EG R VALV E POSITIO N SENSO R CONNECTO R (C107 )
Wir e sid e o f femal e terminal s
YES
(To pag e 11-170 )
NO
YE S
YE S
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Emission Contro l Syste m
Exhaus t Ga s Recirculatio n (EGR ) Syste m (cont'd )
(From pag e 11-169 )
PCM CONNECTO R D (22P )
Chec k fo r a n ope n i n th e wir e
(VCC 2 line) :
Measur e voltag e betwee n th ePC M connecto r terminal s D2 1and D22 .
Is ther e approx . 5 V ?
NO
Substitut e a known-goo d PC M
an d rechec k (se e pag e 11-42 fo r
immobilize r information) . I f
symptom/indicatio n goe s away ,
replac e th e origina l PCM . Repai
r ope n in th e wir e betwee n
th e EG R valv e an d PC M (D21) .
(Fro m pag e 11-169 )
Chec k fo r a n ope n o r shor t i n th e
EG R valv e positio n sensor :
1 . Tur n th e ignitio n switc h OFF .
2 . A t th e senso r side , measur e
resistanc e betwee n th e EG R
valv e positio n senso r 3 P connec -
tor terminal s No . 1 an d No . 2 .
Is ther e continuit y o r resis -tance o f 10 0 k o r higher ?
NO
Chec k fo r a n ope n o r shor t i n th e
EG R valv e positio n sensor .
Measur e resistanc e betwee n th e
EG R valv e positio n senso r 3 P con -
necto r terminal s No . 2 an d No . 3 .
I s ther e 10 0 Kf i o r higher ?
YES
Chec k fo r a n ope n o r shor t i n th e
wir e (EGR L line) :
1 . Reconnec t th e EG R valv e
positio n senso r 3 P connector .
2. Tur n th e ignitio n switc h O N (II) .3. Measur e voltag e betwee n th ePC M connecto r terminal s D1 7and D22 .
Is ther e approx . 1. 2 V ?
(T o pag e 11-171 ) EG
R VALV E POSITIO N SENSO R CONNECTO R
Replac e th e EG R valve . Termina
l sid e o f mal e termina l
Replac e th e EG R valve .
PCM CONNECTO R D (22P )YES
Wir e sid e o f femal e terminal s
(T o pag e 11-171 )
NO
NO
YE S
YE SWir e sid e o f femal e terminal s
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(From pag e 11-170 )
PCM CONNECTO R D (22P )
Chec k fo r a shor t i n th e wir e
(EGR L line) :Chec k fo r continuit y betwee n
PC M connecto r termina l D1 7 an d
th e bod y ground .
I s ther e continuity ? Repai
r ope n in th e wir e betwee n
the EG R valv e an d th e PC M (D17) .
YES
Repai r shor t i n th e wir e betwee nthe EG R valv e an d PC M (D17) .
(From pag e 11-170 )
Chec k fo r a n ope n in th e wir e (IG 1
line) :1. Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e contro l bo x
connector .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n bod y
groun d an d th e contro l bo x
connecto r termina l No . 1 . Wir
e sid e o f femal e terminal s
CONTRO L BO X 4P CONNECTO R (C257 )
Wir e sid e o f femal e terminal s
I s ther e batter y voltage ?
YES
Chec k th e vacuu m routing :
1 . Reconnec t th e vacuu m pump /
gaug e to th e No . 1 1 hose .
2 . Star t th e engin e an d le t i t idle .
3 . A t th e contro l bo x side , con -
nec t th e batter y positiv e ter -
mina l t o th e EG R valv e vacu -
u m contro l solenoi d valv e
connecto r termina l No . 1 .
4 . Whil e watchin g th e vacuu m
gauge , connec t th e batter y neg -
ativ e termina l t o th e EG R valv e
vacuu m contro l solenoi d
valv e connecto r termina l No . 2 . Repai
r ope n in th e wir e betwee n
th e EG R valv e vacuu m contro l
solenoi d valv e an d No . 2 0 EC U
(PCM ) (2 0 A ) fus e i n th e under -
das h fuse/rela y box .
CONTROL BO X 4PCONNECTO R
Is ther e approx . 26. 7 kP a
(20 0 mmHg , 8. 0 in.Hg ) o f vacu -
um withi n 1 second ?
Termina l sid e
o f mal e terminal s
NO
YE SChec k th e vacuu m hoses :1. Tur n th e ignitio n switc h OFF .2. Inspec t th e No . 1 1 an d No . 3
hose s fo r leaks , restriction s o r
misrouting .
Are th e hose s OK ?
(T o pag e 11-172 ) Correc
t a s necessary .
YES
NO
N
O
Replac e th e EG R valv e vacuu m
contro l solenoi d valve .
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Emission Contro l Syste m
Exhaus t Ga s Recirculatio n (EGR ) Syste m (cont'd )
(From pag e 11-171 )
PCM CONNECTO R A (26P )
JUMPE R WIR E
Wir e sid e o f femal e terminal s
Doe s th e engin e stal l o r ru n
rough ? Repai
r ope n in th e wir e betwee n
PCM (A6 ) an d EG R valv e vacuu mcontrol solenoi d valve .
YES
Substitut e a known-goo d PC M
an d rechec k (se e pag e 11-42 fo r
immobilize r information) . I f
symptom/indicatio n goe s away ,
replac e th e origina l PCM .
Chec
k fo r a n ope n in th e wir e (E S
line) :1. Tur n th e ignitio n switc h OF Fand reconnec t th e contro l bo xconnector .2. Reconnec t th e No . 1 1 hos e t o
th e EG R valve .
3 . Star t th e engin e an d le t i t idle .
4 . Connec t PC M connecto r termi -
nal s A 6 an d A1 2 wit h a jumpe r
wire .
NO
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The sca n too l indicate s Diagnosti c Troubl e Cod e (DTC ) P1498 : A hig h voltag e proble m in th e Exhaus t Ga s
Recirculatio n (EGR ) valv e positio n senso r circuit .
The MI L ha s bee n reporte d on .
DT C P149 8 is stored .
Proble m verification :
1 . D o th e PC M Rese t Procedure .
2. Tur n th e ignitio n switc h O N (II) .
Is DT C P149 8 indicated ?
YES
Chec k fo r a n ope n i n th e EG R
valv e positio n senso r
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EG R valv e
positio n senso r connector .
3. Tur n th e ignitio n switc h O N (II) .4. Measur e voltag e betwee n th e
EG R valv e positio n senso r 3 P
connecto r terminal s No . 1 an d
No. 2 .
Is ther e approx . 5 V ?
NO
Chec k fo r ope n i n th e wir e (SG 2
line) :
Measur e voltag e betwee n PC Mconnecto r terminal s D2 2 an d D21 .
I s ther e approx . 5 V ?
NO
Substitut e a known-goo d PC Mand rechec k (se e pag e 11-42 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
the origina l PCM .
Intermitten t failure , syste m is O K
a t thi s time . Chec k fo r poo r con -
nection s o r loos e wire s a t C251 ,
C25 4 (locate d a t lef t shoc k tower) ,
C10 7 (EG R valve ) an d PCM .
EGR VALV E POSITIO N SENSO R CONNECTO R (C107 )
Replac e th e EG R valve . Wir
e sid e o f femal e terminal s
PC M CONNECTO R D (22P )
Repai r ope n i n th e wir e betwee n
PC M (D22 ) an d EG R valv e posi -
tio n sensor . Wir
e sid e o f femal e terminal s
YES
YE
S
NO
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Emission Contro l Syste m
Positiv e Crankcas e Ventilatio n (PCV ) Syste m
Descriptio n
Th e Positiv e Crankcas e Ventilatio n (PCV ) syste m is
designe d t o preven t blow-b y ga s fro m escapin g t o th e
atmosphere . Th e PC V valv e contain s a spring-loade d
plunger . Whe n th e engin e starts , th e plunge r i n th e PC V
valv e is lifte d in proportio n to intak e manifol d vacuu m an d
th e blow-b y ga s is draw n directl y int o th e intak e manifold .
BREATHE R PIP E
PCV HOS E
PCV VALV E
BLOW-B Y VAPO RFRESH AI R
Inspectio n
1. Remov e th e engin e cover . Chec k th e PC V hose s an d
connection s fo r leak s an d clogging .
PCV HOS E
PCVVALV E
BREATHE RPIPE
2. A t idle , mak e sur e ther e is a clickin g soun d fro m th e
PC V valv e whe n th e hos e betwee n th e PC V valv e
an d intak e manifol d i s lightl y pinche d wit h you r fin -
ger s o r pliers .
Gently pinc h her e
If ther e i s n o clickin g sound , chec k th e PC V valv e grom -
me t fo r crack s an d damage . I f th e gromme t i s OK ,
replac e th e PC V valv e an d recheck .
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Evaporative Emissio n (EVAP ) Control s
Descriptio n
Th e evaporativ e emissio n control s ar e designe d t o minimiz e th e amoun t o f fue l vapo r escapin g t o th e atmosphere . Th e
syste m consist s o f th e followin g components :
A . Evaporativ e Emissio n (EVAP ) Caniste r
A n EVA P caniste r i s use d fo r th e temporar y storag e o f fue l vapo r unti l th e fue l vapo r can be purge d fro m th e EVA P
caniste r int o th e engin e an d burned .
B . Vapo r Purg e Contro l Syste m
EVA P caniste r purgin g is accomplishe d b y drawin g fres h ai r throug h th e EVA P caniste r an d int o a por t o n th e throttl e
body . Th e purgin g vacuu m is controlle d b y th e EVA P caniste r purg e valve .
EVA P CANISTE R PURG E VALV E DUT Y CONTROLLE D AFTE R START -
IN G ENGIN E
*: '9 6 - 9 9 model s*1: '0 0 - 0 1 model sC. Fue l Tan k Vapo r Contro l Syste m
Whe n fue l vapo r pressur e in th e fue l tan k is highe r tha n th e se t valu e o f th e EVA P tw o wa y valve , th e valv e open s an d
regulate s th e flo w o f fue l vapo r t o th e EVA P canister .
Durin g refueling , th e fue l tan k vapo r contro l valv e open s wit h th e pressur e in th e fue l tank , an d feed s th e fue l vapo r t o
th e EVA P canister .
'96 - 9 9 models :
FUELTANKPRESSURESENSOR
EVAPTWO WAYVALVE
FUEL TANKEVAP VALVE
FUEL TAN K
EVAP CANISTE RPURGE VALV E
EVAPBYPAS SSOLENOI DVALVE
EVAPCANISTE RVENT SHU T VALV EEVAP CONTRO LCANISTER
EVAPTHRE EWAYVALV E
FUEL FIL LCAP
Fro mNo. 2 0 EC U (PCM )(20 A ) FUS E(in th e under-das hfuse/relay box )
VARIOU SSENSOR S
ENGINE COOLAN T TEMPERATUR E ABOV E 99° F (37°C) * 140° F (60°C)*1
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Emission Control System

Evaporative Emission (EVAP) Controls (cont'd)

'00 - 01 models:

From

No. 20 ECU
(PCM)

(20 A) FUSE

(in the under-dash

fuse/relay box)

FUEL TANK VAPOR

RECIRCULATION

TUBE
EVAP

BYPASS

SOLENOID

VALVE
EVAP

CANISTER

FILTER

EVAP

CANISTER

FUEL TANK VAROR

RECIRCULATION

VALVE
EVAP

TWO WAY

VALVE
FUEL TANK
EVAP

CANISTER

VENT SHUT VALVE
EVAP CANISTER

PURGE VALVE
VARIOUS

SENSORS
INTAKE

MANIFOLD

FUEL

TANK

PRESSURE

SENSOR
FUEL TANK

VAPOR CONTROL

VALVE

FUEL

FILL

CAP
FUEL TANK

VAPOR

SIGNAL

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