1991 ACURA NSX Service Repair Manual

Charging System

Troubleshooting

Alternator/Regulator Test

Use the SUN VAT-40 (or equivalent) tester.
2. Attach the negative tester cable and the voltmeter

negative lead to the top of the intake manifold.

LOAD ADJUSTER

(CARBON PILE)
FULL FIELD

LEAD (BLU)

VOLTMETER

NEGATIVE

LEAD (BLK)

VOLT

SELECTOR

FIELD

SELECTOR

INDUCTIVE

PICK-UP

(GRN)
POSITIVE

CABLE (RED)
NEGATIVE

CABLE (BLK)
VOLTMETER

POSITIVE

LEAD (RED)

1. Attach the positive tester cable and the voltmeter

positive lead to the jump start terminal in the

engine compartment fuse/relay box.

POSITIVE CABLE

VOLTMETER

POSITIVE LEAD

JUMP

START

TERMINAL

- ENGINE COMPARTMENT

FUSE/RELAY BOX
VOLTMETER

NEGATIVE LEAD
NEGATIVE CABLE

NEGATIVE MARK

3. Attach the inductive pick-up to the B terminal wire

of the alternator with its arrow pointing away from

the terminal.

NOTE: The arrow must point away from the B

terminal.

INDUCTIVE PICK-UP

ARROW
ALTERNATOR

B TERMINAL

ALTERNATOR
TEST SELECTOR

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NOTE: B e sur e th e batter y is sufficientl y charge d
(see pag e 23-68 ).
Connec t th e Su n VAT-4 0 (se e
pag e 23-102 ) an d tur n th e selec -
to r switc h t o positio n 1 (star -
ting) .
Star t th e engin e an d le t i t idl e un -
ti l i t reache s norma l operatin g
temperature .
Raise th e engin e spee d t o 2,00 0rpm an d hol d i t there .
Is th e voltag e ove r 15. 1 V ?
Releas e th e accelerato r peda l
and le t th e engin e idle .
Mak e sur e al l accessorie s ar eturne d off . Tur n th e selecto rswitch t o positio n 2 (charging) .
Remove th e inductiv e pick-u p
an d zer o th e ammeter .
Attach th e inductiv e pick-u p t oth e B termina l wir e o f th ealternato r wit h it s arro w pointin gaway fro m th e terminal .
Rais e th e engin e spee d t o 2,00 0
rpm an d hol d i t there .
Is th e voltag e les s tha n 13. 9 V ?
(T o pag e 23-104 ) Replac
e th e voltag e regulator .
Tes t th e batter y (se e pag e23-68).
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Charging Syste m
Troubleshootin g
(From pag e 23-103 )
Appl y a loa d wit h th e VAT-4 0
unti l th e batter y voltag e drop s t o
betwee n 12-13. 5 V .
Is th e amperag e 8 5 A or more ?
With th e engin e spee d stil l a t2,00 0 rpm , full-fiel d th e alter -nator.
Turn th e ignitio n switc h off .
Disconnec t th e 4- P connecto r
fro m th e alternator .
Tur n th e ignitio n switc h O N (II) .
Chec k fo r voltag e in th e YE L wir e
a t th e I G termina l an d i n th e
WHT/GR N wir e a t th e S termina l
o f th e 4- P connector .
I s ther e batter y voltag e in bot h
wires ?
Chargin g syste m is OK .
NOTE : Attac h a prob e to th e VAT-4 0 full-fiel d tes t
lead , an d inser t th e prob e int o th e full-fiel d acces s
hole a t th e bac k o f th e alternator . Switc h th e fiel d
selecto r t o " A (Ground) " positio n momentarily , an d
chec k th e amperag e reading .
CAUTION : Th e voltag e wil l ris e quickl y whe n th e
alternato r i s full-fielded . D o no t le t i t excee d 18 V
o r yo u ma y damag e th e electrica l system .
FULL-FIEL D ACCES S HOL E
END COVE R
REGULATO R(Located insid e th e en d cove r
I s th e alternato r outpu t 8 5 A or
more ?Test an d repai r th e alternato r
(se e pag e 23-106 ).
IG (YEL )
S (WHT/GRN )
Repair ope n in th e YE L wir e o r th eWHT/GR N wire .
Replac e th e voltag e regulator .
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Alternator Replacemen t
1. Disconnec t th e negativ e cabl e fro m th e battery .
2 . Disconnec t th e 4- P connecto r fro m th e alternator .
3 . Remov e th e nu t an d th e BL K wir e fro m th e B
terminal .
BLK WIR ENUT 1 2 N- m(1.2 kg-m , 8. 7 Ib-ft )
4-P CONNECTO R
4. Remov e th e pulle y cove r fro m th e alternator .
PULLEY COVE R
5. Remov e th e nu t fro m th e adjustment-loc k bolt ,
loose n th e mountin g bol t an d th e adjustin g bolt ,
the n remov e th e bel t fro m th e pulley .
ADJUSTMENT-LOC KNUT45 N- m (4. 5 kg-m . 3 3 Ib-ft )
ADJUSTIN G BOL T
8 N- m (0. 8 kg-m , 6 Ib-ft )
ADJUSTMENT-LOC KBOLT
ALTERNATO R
BRACKE T
MOUNTIN G BOL T45 N- m (4. 5 kg-m , 3 3 Ib-ft )
6. Remov e th e adjustin g bolt , adjustment-loc k bol t
an d th e mountin g bolt , the n remov e th e alternato r
fro m th e bracket .
7 . Instal l th e alternato r i n th e revers e orde r o f
removal .
8. Adjus t th e alternato r bel t tensio n afte r installin g th e
alternato r (se e pag e 23-109 ).
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Charging Syste m
Alternato r Overhau l
NOTE: I t i s onl y necessar y t o separat e th e pulley , driv e
end housin g an d roto r whe n th e fron t bearin g need s
replacement .
Loosen th e locknu t wit h 1 0 m m an d 2 2 m m wrenche s
to remov e th e pulle y fro m th e rotor . I f necessary , us e a n
impac t wrench .
TERMINA L INSULATO R
PULLEY
22 m m BO XWRENC H
10 m m BO X WRENC H
EN D COVE R PULLE
Y LOCKNU T
11 5 N- m (11. 5 kg-m , 8 3 Ib-ft )
REA R HOUSIN G ASSEMBLY
BRUS H HOLDE R
INSULATO R
BRUSHE S
Inspection , pag e 23-10 7
SPACE R RIN G
REA R BEARIN GDIOD
E (RECTIFIER ) ASSEMBL YTest, pag e 23-10 7
INSULATO R SLEEV E
BEARIN G RETAINE R
STATO R THROUG H BOL T
Do no t disassemble .
STATOR ASSEMBLY/DRIV E EN D HOUSIN GTest, pag e 23-10 8
PULLE Y LOCKNU T115 N- m(11. 5 kg-m , 8 3 Ib-ft )
ROTO RTest, pag e 23-10 8
CAUTION : D o no t ge t greas e
o r oi l o n th e sli p rings .
FRONT BEARIN G
PULLEY
BRUSH HOLDE R
VOLTAG E REGULATO R
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Rectifier Test

NOTE: The diodes are designed to allow current to

pass in one direction while blocking it in the opposite

direction. Since the alternator rectifier is made up of

eight diodes (four pairs), each diode must be tested for

continuity in both directions with an ohmmeter that has

diode checking capability; a total of sixteen checks.

1. Check for continuity in each direction, between the

B and P, and between the E (ground) and P ter-

minals of each diode pair. All diodes should have

continuity in only one direction.

E (GROUND)

2. If any of the eight diodes fails, replace the rectifier

assembly. (Diodes are not available separately.)
Alternator Brush Inspection

1. Remove the end cover, then take out the brush

holder by removing its two screws.

2. Measure the length of the brushes with a vernier

caliper.

Alternator Brush Length:

Standard: 10.5 mm (0.41 in)

Service Limit: 3.5 mm (0.14 in)

ALTERNATOR BRUSHES

VERNIER CALIPER

If the brushes are less than the service limit,

replace the assembly.ProCarManuals.com

Charging System

Rotor Slip Ring Test

1. Check that there is continuity between the slip rings.

2. Check that there is no continuity between the slip

rings and the rotor or rotor shaft.

ROTOR SHAFT

SLIP RINGS
ROTOR

3. If the rotor fails either continuity check, replace the

alternator.
Stator Test

1. Check that there is continuity between each pair of

leads.

2. Check that there is no continuity between each lead

and the coil core.

LEADS

COIL CORE

3. If the coil fails either continuity check, replace the

alternator.ProCarManuals.com

Alternator Belt Adjustment
Deflectio n Method :
1 . Appl y a forc e o f 10 0 N (10kg , 2 2 Ibs ) betwee n th e
alternato r an d crankshaf t pulley , an d measur e it s
deflection .
Deflection : 11-13. 5 m m (0.43-0.5 3 in )
NOTE : O n a brand-ne w belt , th e deflectio n shoul d
b e 6- 8 m m (0.24-0.3 1 in ) befor e th e bel t ha s
ha d an y runnin g tim e o n th e engine .
ADJUSTIN G BOL T8 N- m (0. 8 kg-m , 6 Ib-ft )
MOUNTIN G BOL T45 N- m (4. 5 kg-m , 3 3 Ib-ft )
ADJUSTMENT-LOC KNUT45 N- m (4. 5 kg-m , 3 3 Ib-ft )CRANKSHAF T PULLE Y
2. I f bel t deflectio n i s incorrect , loose n th e
adjustment-loc k nu t an d th e mountin g bolt .
3 . Tur n th e adjustin g bol t unti l bel t deflectio n i s cor -
rect , the n retighte n th e nu t an d bolt .
4 . Rechec k th e bel t tension . Tensio
n Gaug e Method :
1 . Attac h th e bel t tensio n gaug e t o th e bel t an d
measur e bel t tension .
Tension : 450-65 0 N (45-6 5 kg , 99-14 3 Ibs )
NOTE : O n a brand-ne w belt , th e tensio n shoul d b e
900-110 0 N (90-110 kg, 198-24 3 Ibs) befor e
the bel t ha s ha d an y runnin g tim e o n th e engine .
MOUNTIN G BOL T45 N- m (4. 5 kg-m , 3 3 Ib-ft )
ADJUSTIN G BOL T8 N- m (0. 8 kg-m , 6 Ib-ft )BELT TENSIO N GAUG E07JGG - 001010 A
ADJUSTMENT-LOC KNUT45 N- m (4. 5 kg-m ,33 Ib-ft )
CRANKSHAF T PULLE Y
2. I f bel t tensio n is incorrect , loose n th e adjustment -
loc k nu t an d th e mountin g bolt .
3 . Tur n th e adjustin g bol t unti l bel t tensio n is correct ,
the n retighte n th e nu t an d bolt .
4 . Rechec k th e bel t tension .
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