ACURA NSX 1991 Service Repair Manual

Bleeding
Air Bleedin g wit h AL B Checke r
1. Disconnec t the 6- P inspection connector (PNK )
fro m th e connecto r cove r locate d unde r th e glov e
box , an d connec t th e 6- P inspectio n connecto r t o
th e specia l tool .
CONNECTO RCOVER
ALB CHECKE R07HAJ - SG0010 B 6-P INSPECTIO NCONNECTO R
CAUTION: Plac e th e vehicl e o n leve l groun d wit h
th e wheel s blocked . Pu t th e transmissio n in neutra l
for manua l transmissio n models , o r i n fo r auto -
mati c transmissio n models .
2 . Fil l th e modulato r reservoi r t o th e MA X leve l line .
NOTE : D o no t reus e aerate d brak e flui d tha t ha s
bee n ble d fro m th e powe r unit .
3 . Blee d high-pressur e flui d fro m th e maintenanc e
bleeder wit h th e specia l tool.BLEEDE R T-WRENC H07HAA-SG00100or07HAA-SG00101
SOLENOI D UNI T
ACCUMULATOR /PRESSURE SWITC HPOWERUNIT
MAINTENANC EBLEEDER8 x 1.2 5 mm9 N- m (0. 9 kg-m ,6.5 Ib-ft )
4. Star t th e engin e an d releas e th e parkin g brake .
NOTE : Depres s th e brak e peda l firml y whil e tes t i n
progres s ligh t i n ON .
5. Ther e shoul d b e a t leas t tw o stron g kickbacks .
I f not , repea t step s 2 throug h 5 , a s necessary .
6 . Fil l th e modulato r reservoi r u p t o th e MA X leve l
line.
RESERVOI R CA P
MAX LEVE L LIN E
7. Instal l th e reservoi r cap .
8 . Chec k th e anti-loc k brak e syste m functio n i n al l
mode s b y usin g th e AL B checker .
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ABS Contro l Uni t
Replacemen t
SRS component s ar e locate d in thi s area . Revie w th e SR S
componen t locations , precautions , an d procedure s in th e
SR S
sectio n 2 4 befor e performin g repair s o r service .
1 . Remov e th e dashboar d lowe r cove r an d glov e box ,
an d disconnec t th e ligh t connector .
GLOVE BO X
DASHBOAR D LOWE R COVE R
2. Mov e th e heate r duc t t o th e righ t an d remov e it .
HEATE R DUC T
3. Disconnec t th e connector s fro m th e AB S contro l uni t
b y removin g th e wir e harnes s band .
ABS CONTRO L UNI T
4. Remov e th e fou r contro l uni t attachin g bolts , the n
remov e th e bracke t wit h th e contro l unit .
5. Remov e th e AB S contro l uni t fro m th e bracket .
ABS CONTRO L UNI T
BRACKE T
CONTRO L UNI T
ATTACHIN G BOLT S
10 N-m (1.0 kg-m, 7 Ib-ft)
6. Installatio n i s th e revers e o f remova l procedure .
NOTE : Afte r installation , star t th e engin e an d mak e
sure tha t th e AB S indicato r ligh t goe s off .
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Fail-Safe Relays/Moto r Rela y
Inspectio n
1. Chec k fo r continuit y betwee n terminal s an d
There shoul d b e n o continuity .
2. Connec t a 1 2 V batter y acros s terminal s an d
There shoul d b e continuit y betwee n terminal s
and
Pulsers/Sensor s
Inspection
1. Chec k th e pulse r fo r chippe d o r damage d teeth .
2 . Measur e ai r ga p betwee n th e senso r an d pulse r al l
th e wa y aroun d whil e rotatin g th e driveshaf t b y
hand .
(A) - (B) = Standard: 0.4-1.0 mm
(0.02-0.04 in.)
NOTE: I f th e ga p exceed s 1. 0 m m (0.0 4 in) , th e
probabilit y i s a distorte d knuckl e whic h shoul d b e
replaced .
KNUCKL E
SENSOR
PULSER
ABS Control Unit
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Pulsers/Sensors
Front Senso r Replacemen t
NOTE:
• B e carefu l whe n installin g th e sensor s t o avoi d
twistin g th e wires .
• Afte r senso r replacemen t confir m prope r opera -
tion (se e pag e 19-43 ).
CORROSIO N RESISTAN T BOL T6 x 1. 0 m m10 N- m (1. 0 kg-m . 7 Ib-ft )
6 x 1. 0 m m10 N- m (1. 0 kg-m ,7 Ib-ft )
8 x 1.2 5 mm22 N- m (2. 2 kg-m ,16 Ib-ft )
Rear Senso r Replacemen t
8 x 1.2 5 mm22 N- m (2. 2 kg-m , 1 6 Ib-ft )
NOTE :
• B e carefu l whe n installin g th e sensor s t o avoi d
twistin g th e wires .
• Afte r senso r replacement , confir m prope r opera -
tion (se e pag e 19-43 ).
CORROSIO N RESISTAN T BOL T
6 x 1. 0 m m10 N- m (1. 0 kg-m , 7 Ib-ft )
6 x 1. 0 m m10 N- m (1. 0 kg-m ,7 Ib-ft )
6 x 1 0 m m10 N- m (1. 0 kg-m ,7 Ib-ft )
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Special Tools

Ref.
No.

Tool Number

07PAZ-0010100
Description

SCS Service Connector
Qty

1

19-84('91-'93)('94-'96)Page ReferenceProCarManuals.com

Component Location s
ENGINE CONTRO L MODUL E (ECM )
ABS CONTRO L UNI T
UNDER-HOO D
FUSE/RELA Y BO X
RIGHT-FRON T
WHEE L SENSO R RIGHT-REA
R WHEE L SENSO R
TRANSMISSIO N CONTRO L MODUL E (TCM )
THROTTL E BOD Y
THROTTL E ACTUATO R
LEFT-REARWHEEL SENSO R
TC S SWITC H
LEFT-FRON T
WHEE L SENSO R
TCS CONTRO L UNI T
LATERAL ACCELERATION (Lg) SENSOR
A/T GEA R POSITIO N SWITC H
UNDER-DAS H FUS E BO X
GAUG E ASSEMBL Y UNDER-HOO
D FUSE/RELA Y BO X
BRAK E LIGHTS/HOR N (2 0 A ) FUS E
TC S INDICATO R LIGH T
I G S W (A ) (5 0 A ) FUS E
UNDER-DAS H FUS E BO X CLOC
K (7. 5 A ) FUS E
BACK-U P LIGHTS/ALTERNATOR /
TUR N SIGNAL S (1 5 A ) FUS E
STEERIN
G ANGL E SENSO R
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System Descriptio n
Outline
Role o f Syste m
Th e NSX/NSX- T tractio n contro l i s a variabl e syste m designe d t o enhanc e tractio n durin g acceleratio n an d cornering . I t
doe s s o b y determinin g th e optimu m amoun t o f whee l spi n fo r an y give n drivin g situation , the n suppressin g surplu s
engin e powe r accordingly .
Thi s versio n o f TC S ha s a latera l acceleratio n (Lg ) senso r an d a deceleratio n contro l functio n t o improv e tractio n contro l
durin g acceleratio n an d deceleratio n whil e cornering . Whe n downshiftin g quickl y t o a ver y lo w gea r o n a slipper y surface ,
th e drivin g wheel s ten d t o sli p becaus e o f engin e braking , resultin g i n lowe r directiona l stability . T o counterac t this , th e
deceleratio n contro l functio n control s engine braking wit h th e TC S contro l unit .
Constructio n an d Functio n
Th e TC S contro l uni t get s signal s abou t th e vehicle' s speed , direction , an d roa d condition s fro m sensor s a t th e wheel s an d
th e steerin g column . Base d o n thes e signals , th e contro l uni t wil l determin e th e optimu m amoun t o f whee l spin . Becaus e
th e syste m is variable , th e contro l uni t ma y determine , dependin g o n th e drivin g conditions , tha t som e whee l spi n i s bene -
ficia l (thu s enhancin g straight-lin e acceleration) , o r tha t n o whee l spi n i s beneficia l (thu s enhancin g cornering) . Fo r an y
give n drivin g situation , th e contro l uni t wil l determin e th e amoun t o f whee l spi n bes t suite d t o th e driver' s need s and , i f
necessary , wil l the n signa l th e throttl e actuato r an d Engin e Contro l Modul e (ECM ) t o reduc e engin e power .
Th e syste m is automaticall y "ready " wheneve r th e engin e i s started , bu t ca n b e manuall y cancele d wit h th e TC S switch .
However , onc e activated , th e syste m canno t b e cancele d unti l i t i s onc e agai n in th e read y state .
ENGIN E CONTRO L MODUL E (ECM )
STEERIN G ANGL E SENSO R
TC S SWITC H RIGHT-REA
R WHEE L SENSO R
THROTTL E BOD Y
ABS CONTRO L UNI T
RIGHT-FRON T
WHEE L SENSO R THROTTL
E ACTUATO R
LEFT-REARWHEEL SENSO R
LEFT-FRON T
WHEE L SENSO R TC
S CONTRO L UNI T
LATERAL ACCELERATION (Lg) SENSOR
Components :
• Whee l sensors : Th e TC S "shares " th e whee l sensor s wit h th e ABS . Th e whee l sensor s transmi t whee l spee d signal s t o
th e TC S throug h th e AB S contro l unit .
• Steerin g angl e sensor : Th e steerin g angl e senso r signal s th e TC S contro l uni t abou t th e amoun t o f steerin g angle .
• Latera l acceleratio n (Lg ) sensor : Th e L g senso r detect s th e latera l acceleratio n o f th e vehicl e an d signal s th e TC S con -
trol unit .
• TC S contro l unit : Th e TC S contro l uni t detect s th e drivin g conditio n signal s fro m th e sensor s and , i f necessary , signal s
th e throttl e actuato r an d th e Engin e Contro l Modul e (ECM) . Thi s versio n ha s a latera l acceleratio n (Lg ) sensor , whic h
improve s th e tractio n contro l performanc e durin g cornering .
• Throttl e actuator : Th e throttl e actuato r open s an d close s th e throttl e valv e accordin g to th e tractio n contro l signa l fro m
the Engin e Contro l Modul e (ECM) .
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Construction an d Functio n
TCS Contro l uni t
Acceleratio n Contro l
Whe n th e driv e whee l spee d exceed s th e vehicl e spee d b y a give n amount , th e TC S contro l uni t judge s tha t th e driv e
wheel s ar e slipping , an d it output s th e tractio n contro l signa l t o reduc e engin e power .
Deceleratio n Contro l
Whe n th e driv e whee l spee d drop s belo w th e vehicl e spee d b y a give n amount , th e TC S contro l uni t judge s tha t th e driv e
wheel s ar e slipping , an d it output s th e tractio n contro l signa l t o contro l engin e brakin g properly .
Handlin g Contro l
Base d o n signal s abou t drivin g whee l an d drive n whee l rotationa l speeds , th e contro l uni t calculate s th e car' s "yaw" rate
(th e tur n rat e o f th e car' s body) . Base d o n signal s fro m th e steerin g angl e sensor , th e contro l uni t als o calculate s th e ya w
rat e expecte d b y th e driver . I f th e differenc e betwee n actua l an d expecte d ya w rate s is substantia l — tha t is , i f th e directio n
of th e car' s bod y will excee d the driver' s expecte d lin e — the contro l unit signal s the throttl e actuator , whic h close s the
throttl e valve , thu s reducin g engin e powe r an d maintainin g th e expecte d line .
Roug h Roa d Contro l
Base d o n signal s fro m th e whee l sensors , th e contro l uni t detect s a roug h roa d base d o n frequenc y o f whee l rotationa l
vibration . Th e contro l uni t the n signal s th e throttl e actuato r t o rela x engine power, thu s improvin g acceleratio n efficiency .
Gri p Contro l
Base d o n signal s abou t whee l spee d an d latera l acceleration , th e contro l uni t determine s th e efficienc y o f th e gri p o f th e
tire s o n th e roa d an d signal s th e throttl e actuato r t o rela x engine power i f necessary , thu s improvin g grip .
Mai n Contro l Bloc k
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System Descriptio n
Constructio n an d Functio n
Fail-Safe Functio n
I f th e contro l uni t detect s a n abnormality , i t shut s th e
tractio n contro l syste m of f an d cause s th e TC S indicato r
ligh t t o com e on . Howeve r i f th e abnormalit y i s detecte d
whil e th e TC S i s activated , th e contro l uni t firs t estab -
lishe s th e appropriat e whee l spi n velocity , the n shut s
th e syste m down , thu s preventin g excessiv e whee l spin .
Self-Diagnosi s Functio n
I f th e contro l uni t detect s a n abnormality , i t record s a
Diagnosti c Troubl e Cod e (DTC ) whic h ca n b e use d t o
diagnos e th e problem . Th e DT C is show n a t th e TC S
indicato r ligh t whe n th e Servic e Chec k connecto r termi -
nal s ar e connecte d wit h th e SC S servic e connector .
Steerin g Angl e Detectio n
Steerin g angl e is detecte d b y th e steerin g angl e sensor ,
locate d o n th e steerin g column . Th e senso r use s tw o
magneto-resisto r (MR ) element s t o determin e steerin g
angl e an d directio n o f rotation . Whe n th e drive r turn s
th e steerin g wheel , a magne t i n th e steerin g shaf t gener -
ate s wave s i n th e "MR " elements . Thes e wave s ar e
amplifie d an d converte d int o signal s whic h th e contro l
uni t ca n interpre t a s angl e an d directio n o f turn .
MR ELEMEN T
TCS INDICATO R LIGH T
MRELEMEN T
Vehicle Spee d Detectio n
Whee l rotatio n spee d i s detecte d b y th e whee l sensors ,
locate d a t eac h wheel . Th e signal s ar e sen t t o th e con -
tro l unit , whic h compare s eac h wheel' s spee d an d deter -
mine s whethe r tractio n contro l i s required .
GEAR PULSE R
WHEEL SENSO R
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Lateral Acceleration Detection

Lateral acceleration is detected by the lateral accelera-

tion (Lg) sensor located under the rear center trim panel.

The Lg sensor varies the output voltage in accordance

with the left or right side acceleration and sends it to the

TCS control unit as a lateral acceleration signal.
Lg SENSOR

90 degrees

VOLTAGE
RIGHT SIDE ACCELERATION

OUTPUT CHARACTERISTIC

LEFT

TURN
RIGHT

TURN
LATERAL

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