1991 ACURA NSX relay

Idle Contro l Syste m
Air Conditionin g Signa l
(From pag e 11-117 )
I s ther e a clickin g nois e fro m th e
A/ C compresso r clutch ?
Chec k fo r th e operatio n o f th e
A/C :1. Star t th e engine .
2 . Tur n th e blowe r switc h ON .
3 . Tur n th e A/ C switc h ON .
Doe s th e A/ C operate ?
Ai r conditionin g signa l i s OK . A/
C CLUTC H RELA Y 4P CONNECTO R
Chec k fo r a n ope n in th e wire :
Momentaril y connec t th e No . 4 ter -
mina l o f th e 4 P connecto r o n th e
A/ C clutc h rela y t o bod y groun d
severa l times .
WIRE SID E O F
FEMAL E TERMINAL S
I s ther e a clickin g nois e fro m th e
A/ C compresso r clutch ? Se
e ai r conditione r inspectio n (se e
sectio n 22 ).
Repai r ope n in th e wir e betwee n
th e EC M (AS ) an d th e A/ C clutc h
relay.
ECM CONNECTOR S
Chec k fo r a n ope n in th e wire :
Measur e voltag e betwee n EC M
connecto r terminal s C 2 an d A26 . WIR
E SID E O F FEMAL E TERMINAL S
I s voltag e les s tha n 1. 0 V ? Repai
r ope n in th e wir e betwee n
th e EC M (C2 ) an d th e A/ C switch .
Substitut e a known-goo d EC M
an d recheck . I f symptom/indi -
catio n goe s away , replac e th e
origina l ECM .
Se e th e ai r conditione r inspec -
tio n (se e sectio n 22 ).
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Starter Switch Signal

This signals the ECM when the engine is cranking.

Inspection of Starter Switch Sig-

nal.
NOTE:

• M/T: Clutch pedal must be depressed.

• A/T: Transmission in position.

ECM CONNECTORS

Measure voltage between ECM

connector terminals C6 and A26

with the ignition switch in the

start position.

WIRE SIDE OF FEMALE TERMINALS

Is there battery voltage?

Is the fuse OK?
Repair short in the wire

between the ECM (C6) and

the No. 7 STARTER SIGNAL

(7.5 A) fuse or the PGM-FI

main relay.

Replace the No. 7 STARTER

SIGNAL (7.5 A) fuse.
Starter switch signal is OK.

Repair open in the wire between

the ECM
(C6)
and the No. 7

STARTER SIGNAL (7.5 A) fuse.
Inspect the No. 7 STARTER SIG-

NAL (7.5 A) fuse in the under-

dash fuse box.ProCarManuals.com

Fuel Pum p Rela y
Troubleshootin g Flowchar t
Inspection o f fue l pum p relay .
Tur n th e ignitio n switc h t o STAR T
(III) position .
Does th e engin e start ?
Chec k fo r a n ope n in th e circuit :
1 . Sto p th e engine .
2. Tur n th e ignitio n switc h O N (II) .3. Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e batter y voltage ?
Proble m verification :
1 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n o
loa d (A/ T in position ,M/T in neutral ) unti l th e radia -
to r fa n come s on , the n le t i t
idl e fo r a t leas t on e minute .
2. Tur n th e ignitio n switc h OFF .3. Disconnec t # 4 hos e fro m th e
instal l pipe , connec t vacuu m
pum p t o th e hose .
4 . Appl y vacuu m 2 7 t o 4 0 kp a
(200 t o 300 mmHg , 8 to 1 2in.Hg) .
5 . Star t th e engine .
6 . Hol d engin e spee d a t 6,50 0
rpm (A/ T in position ,M/T in neutral) .
7 . Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e les s tha n 1. 0 V ? Inspec
t th e fue l pum p resisto r
(se e pag e 11-141 ).
ECM CONNECTO R F (26P )
WIR E SID E O F FEMAL E TERMINAL S
(T o pag e 11-140 )
4 HOS E
CONTRO LBOX
VACUU M PUMP /GAUGEA973X-04 1-XXXX X
Substitut e a known-goo d EC M
an d recheck . I f prescribe d volt -
ag e i s no w available , replac e th e
origina l ECM .
Fue l pum p rela y circui t i s OK .
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Fuel Suppl y Syste m
Fuel Pum p Rela y
(From pag e 11-139 )
FUEL PUM P RELA Y 4 P CONNECTO R
Chec k fo r ope n i n th e fue l pum p
relay:1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connec -tor F (26P ) fro m th e ECM .3. Disconnec t th e 4 P connecto r
fro m th e fue l pum p relay .
4 . Connec t fue l pum p rela y con -
necto r terminal s No . 2 to No . 4 .
5. Tur n th e ignitio n switc h O N (II) .6. Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground . CAUTION
: * th e "A " connecto r mus t b e
disconnecte d fo r thi s tes t o r th e EC M
will b e damaged .
WIRE SID E O F FEMAL E TERMINAL S
EC M CONNECTO R F (26P )
WIR E SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ?
Replace th e fue l pum p relay .
Chec k fo r a n ope n in th e wire :
1 . Remov e th e jumpe r wire .
2 . Measur e voltag e betwee n th e
fue l pum p rela y connecto r ter -
mina l No . 2 an d bod y ground .
I s ther e batter y voltage ? Repai
r ope n i n wir e betwee n th e
fue l pum p rela y an d th e No . 5
BACK-U P LIGHT S ALTERNATO R
TUR N SIGNAL S (1 5 A ) fus e in th e
under-das h fus e box) .
Repai r ope n o r shor t i n wir e
betwee n EC M (F4 ) an d th e fue l
pum p relay .
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Fuel Pum p Resisto r
Troubleshootin g Flowchar t
— Engin e wil l no t start .
— Inspectio n o f fue l pum p resis -
tor.
Chec k th e operatio n o f th e PGM -
F I mai n relay :
1 . Disconnec t th e fue l pum p
resisto r 2 P connector .
2 . Measur e voltag e betwee n fue l
pum p resisto r connecto r ter -
mina l No . 2 an d bod y groun d
when th e ignitio n switc h i sfirs t turne d O N (II) .
I s ther e batter y voltage ?
(fo r 2 seconds )
Doe s th e engin e start ?
Chec k fo r a n ope n in th e wire :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e C48 6 (6P ) con -
necto r (locate d behin d th e
sea t bac k panels) .
3 . Measur e voltag e betwee n th e
C48 6 (6P ) connecto r termina l
No . 3 an d bod y groun d whe n
the ignitio n switc h i s firs tturne d ON .
I s ther e batter y voltage ?
(fo r 2 seconds ) FUE
L PUM P RESISTO R 2P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
Inspec t th e PGM-F I mai n rela y
(se e pag e 11-143 ).
Replac e th e fue l pum p resistor .
C489 CONNECTO R (6P )
Inspec t th e fue l pum p (se e pag e
11-142 ).
TERMINA L SID E O F MAL E TERMINAL S
JUMPE
R WIR E
Chec k fo r a n ope n i n th e fue l
pum p resistor :
1 . Tur n th e ignitio n switc h OFF .
2 . Connec t fue l pum p resisto r
connecto r terminal s No . 1 an d
No. 2 wit h a jumpe r wire .3. Tur n th e ignitio n switc h t o
STAR T position .
Repai r ope n i n BLK/RE D wir e
betwee n th e fue l pum p resisto r
an d th e fue l pump .
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PGM-FI Mai n Rela y
Descriptio n
Th e PGM-F I mai n rela y actuall y contain s tw o individua l
relays .
Th e rela y i s locate d behin d th e passenger' s sea t bac k
panel .
On e rela y i s energize d wheneve r th e ignitio n i s o n whic h
supplie s th e batter y voltag e t o th e ECM , powe r t o th e
fue l injectors , an d powe r fo r th e secon d relay .
Th e secon d rela y i s energize d fo r 2 second s whe n th e
ignitio n i s switche d on , an d whe n th e engin e i s runnin g
whic h supplie s powe r t o th e fue l pump . Rela
y Testin g
NOTE : I f th e ca r start s an d continue s t o run , th e PGM-F I
mai n rela y is OK .
1 . Remov e th e PGM-F I mai n relay .
2 . Attac h th e batter y positiv e termina l t o th e No . 3 *
termina l an d th e batter y negativ e termina l t o th e
No . 2 * termina l o f th e PGM-F I mai n relay . The n
chec k fo r continuit y betwee n th e No . 5 * termina l an d
No . 2 termina l o f th e PGM-F I mai n relay .
• I f ther e i s continuity , g o o n t o ste p 3 .
• I f ther e i s n o continuity , replac e th e rela y an d
retest .
3 . Attac h th e batter y positiv e termina l t o th e No . 4 ter -
mina l an d th e batter y negativ e termina l t o th e No .
7 * termina l o f th e PGM-F I mai n relay . The n chec k
tha t ther e i s continuit y betwee n th e No . 3 termina l
an d No . 1 termina l o f th e PGM-F I mai n relay .
• I f ther e is continuity , g o o n t o ste p 4 .
• I f ther e i s n o continuity , replac e th e rela y an d
retest .
4 . Attac h th e batter y positiv e termina l t o th e No . 1 ter -
mina l an d batter y negativ e termina l t o th e No . 2 *
termina l o f th e PGM-F I mai n relay . The n chec k tha t
ther e i s continuit y betwee n th e No . 5 * termina l an d
No . 2 termina l o f th e PGM-F I mai n relay .
• I f ther e i s continuity , th e rela y i s OK ;
I f th e fue l pum p stil l doe s no t work , g o t o
Harnes s Testin g in th e nex t column .
• I f ther e i s n o continuity , replac e th e rela y an d
retest .
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(From pag e 11-144 )
Chec k fo r a n ope n in th e wire :
Measur e voltag e betwee n th e
PGM-F I mai n rela y 4 P connecto r
termina l No . 4 an d bod y ground . PGM-F
I MAI N RELA Y 4 P CONNECTO R
I s ther e batter y voltage ? —
Replac e th e I G COI L (3 0 A )
fus e i n th e engin e compart -
men t fuse/rela y box .
— Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e I G COI L
(3 0 A ) fuse . WIR
E SID E O F FEMAL E TERMINAL S
Chec k fo r a n ope n o r shor t i n th e
wire :
1 . Tur n th e ignitio n switc h t o th e
STAR T (III ) position .
NOTE:• M/T : Clutc h peda l mus t b e
depressed .
• A/T : Transmissio n in
position .
2 . Measur e th e voltag e betwee n
th e PGM-F I mai n rela y 8 P con -
necto r termina l No . 3 an d
bod y ground . PGM-F
I MAI N RELA Y 8 P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ? —
Replac e th e No . 7 STARTE R
SIGNA L (7. 5 A ) fus e i n th e
under-das h fus e box .
— Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e No . 7
STARTE R SIGNA L (7. 5 A ) fuse .
Chec k fo r a n ope n in th e wire :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e EC M connec -
to r A (2 6 P ) fro m th e ECM .
3 . Chec k fo r continuit y betwee n
th e PGM-F I mai n rela y 8 P
connecto r termina l No . 2 an d
EC M connecto r termina l A4 .
WIRE SID E O F FEMAL E TERMINAL S
I s ther e continuity ? Repai
r ope n i n th e wir e betwee n
th e EC M (A4 ) an d th e PGM-F I
mai n relay .
(T o pag e 11-146 )
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Fuel Suppl y Syste m
PGM-F I Mai n Rela y
(From pag e 11-145 )
Chec k fo r a n ope n in th e wire :
1 . Reconnec t th e EC M connecto r
A (26P) .2. Reconnec t th e PGM-F I mai n
rela y 4 P an d 8 P connectors .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n
EC M connecto r terminal s
A13, C1, an d A12 .
ECM CONNECTOR S
WIRE SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ? Repai
r ope n i n th e wir e
betwee n th e EC M (A13 , C D
an d th e PGM-F I mai n relay .
Replac e th e PGM-F I mai n
relay.
Chec k fo r a n ope n in th e ECM :
1 . Tur n th e ignitio n switc h OFF .
2 . Measur e voltag e betwee n
EC M connecto r terminal s A 4
an d A1 2 whe n th e ignitio n
switc h i s firs t turne d o n fo r
tw o seconds .
Is ther e 1. 0 V or less ?
Substitut e a known-goo d EC M
an d recheck . I f prescribe d volt -
ag e is no w available , replac e th e
origina l ECM .
Chec k th e PGM-F I mai n rela y
(se e pag e 11-143 ).
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