ACURA NSX 1991 Service Repair Manual

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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Radiator an d Condense r Fa n Control s
Componen t Locatio n Inde x
RADIATO R FA NLOW RELA YWire colors : WHT/BLU ,YEL/BLK, RE D an d GRN/BL K
RADIATO R FA N
HIG H RELA Y
Wire colors : WHT/BL UBLK, YEL/BL K an d BLU/RE D
CONDENSE R FA N RELA Y
Wir e colors : WHT/GRN , BL K
YEL/BL K an d ORN/BL U
RIGH T CONDENSE R
FA N MOTO R
Test , pag e 23-11 7
Replacement , se e sectio n 2 2
UNDER-HOO D RELA Y BO X A
RADIATO R FA N
RESISTO RTest, pag e 23-116 ,
A/C TRIPL E PRESSUR E
SWITC H
See sectio n 2 2
LEF T CONDENSE R FA N
MOTO R
Test, pag e 23-11 7Replacement , se e sectio n 2 2
RADIATO R FA N MOTO RTest, pag e 23-11 7Replacement , se e sectio n 5
CLIMAT E CONTRO L UNI TTroubleshooting , se e sectio n 2 2
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THROTTLE VALV E CONTRO L
MOTO R RELA Y
ECM
FAN CONTRO LUNIT
ENGIN E COMPARTMEN T
FA N RELA Y (A/T )
Wir e colors : YEL/BLK ,
BLU/RED , WHT/GRN ,
an d WHT/BL U
Test , pag e 23-11 9
RADIATO R FA N CONTRO L SENSO R
Test, pag e 23-12 0
ENGIN E COMPARTMEN T FA N MOTO R (A/T )Test, pag e 23-11 8Replacement , pag e 23-11 8
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Radiator and Condenser Fan Controls

Description

Fan control system:

The cooling fan system is comprised of the radiator fan, condenser fan (left and right), engine compartment fan, radiator

fan low relay, radiator fan high relay, condenser fan relay, engine compartment fan relay, radiator fan resistor, radiator

fan control sensor, A/C pressure switch, fan control unit, climate control unit, and ECM.

The fan control unit controls the operation of the radiator fan and condenser fans.

It uses inputs from the radiator fan control sensor and the A/C pressure switches (A and B) in the A/C system to deter-

mine when the fans should run and at what speed.

Additionally, the temperature switch shuts down the A/C system if the engine coolant temperature (ECT) exceeds

266°F (130°C). If the pressure in the A/C system is higher than normal, pressure switch A closes and the fans will run at

high speed only. See the A/C section for the description and specifications of that function.ProCarManuals.com

Troubleshooting
NOTE: Th e number s i n th e tabl e sho w th e troubleshootin g sequence .
*: Refe r t o sectio n 2 2 fo r A/ C pressur e inspectio n o f th e A/ C system .
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