ACURA NSX 1997 Service Repair Manual

Drive B y Wir e Syste m
System Descriptio n
The Driv e B y Wir e Syste m is a n electroni c throttl e contro l system .
Thi s syste m consist s of the throttl e valv e contro l moto r an d Throttl e Positio n (TP ) senso r assemble d i n Throttl e Bod y (TB) ,
th e accelerato r positio n sensor , an d th e Engin e Contro l Modul e (ECM) .
Driv e B y Wir e Syste m Functions :
Idl e Contro l Functio n
Whe n th e engin e i s idling , th e EC M control s th e throttl e valv e contro l moto r t o maintai n th e prope r idl e spee d accordin g
t o engin e loads .
Acceleratio n Contro l Functio n
Whe n th e accelerato r peda l i s depressed , th e EC M open s th e throttl e valv e dependin g o n th e accelerato r positio n senso r
signals .
(cont'd)
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Drive By Wire System

System Description (cont'd)

Cruise Control Function

The ECM controls the throttle valve control motor to maintain the set speed when the cruise control system is operating.

The throttle valve control motor takes the place of the cruise control actuator.

Traction Control System (TCS) Function

If wheel spin occurs during acceleration or cornering, the TCS control unit requests the ECM to reduce the engine power

by retarding the ignition timing and closing the throttle valve. If the wheels lock during deceleration, the TCS control unit

signals the ECM to open the throttle valve.

Engine Protection Function

When the engine speed exceeds 8,000 rpm (M/T) or 7,500 rpm (A/T), the ECM controls the throttle valve, regardless of the

accelerator position, to protect the engine from over-revving.

Fail-safe Function

On this system, the ECM monitors the position of the accelerator pedal with a dual circuit type accelerator position sensor,

and monitors the operation of the throttle valve control motor with a Throttle Position (TP) sensor.

When an abnormality occurs in the system, the ECM restricts the operation of the throttle valve control motor to allow the

engine to continue to run.ProCarManuals.com

Idle Contro l Syste m
Air Conditionin g Signa l
This signal s th e EC M whe n ther e is a deman d fo r coolin g fro m th e ai r conditionin g system .
Inspectio n o f Ai r Conditionin gSignal.
Check fo r a shor t i n th e wir e
(AC S line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e 12 P connecto r
fro m th e coolin g fa n contro l
unit.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 C 2 an d
A26 .
Is ther e approx . 1 0 V ?
Chec k fo r a n ope n i n th e wir e
(ACS line) :1. Tur n th e ignitio n switc h OFF .
2 . Reconnec t th e 12 P connecto r t o
th e coolin g fa n contro l unit .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Momentaril y connec t EC M
connecto r terminal s A 8 t o
A2 6 severa l time s wit h ajumpe r wire .
(To pag e 11-119 )
Check fo r a shor t i n th e wir e
(AC S line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e EC M connec -
to r C (12P ) fro m th e ECM .
3 . Chec k fo r continuit y betwee n
EC M connecto r termina l C 2
an d bod y ground .
I s ther e continuity ?
Substitut e a known-goo d
EC M an d rechec k (se e pag e
11-3 9 fo r immobilize r infor -
mation) . I f prescribe d voltag e
i s no w available , replac e th e
origina l ECM .
Se e th e ai r conditione r inspec -
tio n (se e sectio n 22 ). Repai
r shor t i n th e wir e
betwee n th e EC M (C2 ) an d th e
coolin g fa n contro l unit .
Se e th e ai r conditione r inspec -
tio n (se e sectio n 22 ).
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(From pag e 11-118 )
Chec k th e A/ C operation :
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 . 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
several times .
Is 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.
Is voltag e les s tha n 1. 0 V ? Repai
r ope n i n th e wir e betwee n
th e EC M (C2 ) an d th e A/ C switch .
I
s ther e a clickin g nois e fro m th e
A/ C compresso r clutch ?
Substitute a known-goo d EC M
an d rechec k (se e pag e 11-3 9
fo r immobilize r information) . I f
symptom/indicatio n goe s
away , replac e th e origina l
ECM.See th e ai r conditione r inspec -
tio n (se e sectio n 22 ).
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Idle Contro l Syste m
Alternato r (ALT ) F R Signa l
This signal s th e EC M whe n th e Alternato r (ALT ) i s charging .
Inspection o f AL T F R Signal .
Chec k fo r a shor t i n th e wir e
(ALT F line) :
1 . Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
2 . Tur n th e ignitio n switc h O N (II) .
3 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d
A26.
Is ther e approx . 5 V ?
Chec k th e operatio n o f th e ALT :
1. Tur n th e ignitio n switc h OFF .2. Reconnec t th e AL T GRI M 4 Pconnecto r t o th e ALT .
3 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n oloa d (A/ T in o r position ,
M/ T in neutral ) unti l th e radiato r
fa n come s on , the n le t i t idle .
4 . Measur e voltag e betwee n EC M
connecto r terminal s D 5 an d
A26 .
I
Doe s th e voltag e decreas e whe n
headlight s an d rea r defogge r ar e
turne d on ?
(T o pag e 11-121 ) Chec
k fo r a shor t i n th e wir e
(ALT F line) :1. Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e negativ e bat -
ter y cabl e fro m th e battery .
3 . Disconnec t th e EC M connec -
to r D (22P ) fro m th e ECM .
4 . Chec k fo r continuit y betwee n
EC M connecto r termina l D 5
an d bod y ground .
I s ther e continuity ? Repai
r shor t i n th e wir e betwee n
the EC M (D5 ) and th e ALT .
Substitut e a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f pre -
scribe d voltag e is no w available ,
replac e th e origina l ECM .
AL T F R signa l i s OK .
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(From pag e 11-120 )
Chec k fo r a n ope n i n th e wir e
(ALT F line) :1. Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e negativ e batter y
cabl e fro m th e battery .
3 . Disconnec t th e EC M connec -
to r D (22P ) fro m th e ECM .
4 . Disconnec t th e GR N 4 P con -
necto r fro m th e ALT .
5 . Connec t No . 2 termina l t o bod y
groun d wit h a jumpe r wire .6. Chec k fo r continuit y betwee n
EC M connecto r termina l D 5
an d bod y ground .
I s ther e continuity ? Repai
r ope n in th e wir e betwee n
the EC M (D5 ) and th e ALT .
See th e AL T inspectio n (se esectio n 23 ).
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Idle Contro l Syste m
Automati c Transaxl e (A/T ) Gea r Positio n Signa l
Does th e indicato r ligh t prop -erly?See th e A/ T gea r positio n indica -
to r inspectio n (se e sectio n 14 ).
Chec k fo r a shor t i n th e wir e
(ATF P N line) :1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e SO P (C412 )connecto r fro m th e gaug eassembly .3. Disconnec t th e 26 P connecto r
fro m th e TCM .
4 . Tur n th e ignitio n switc h O N (II) .
5 . Measur e voltag e betwee n
EC M connecto r terminal s B 4
an d A26 .
Is ther e approx . 5V ? Chec
k fo r a shor t i n th e wir e
(AT F O N line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connecto r
B (16P ) fro m th e ECM .
3 . Chec k fo r continuit y betwee n
EC M connecto r termina l B 4
an d bod y ground .
I s ther e continuity ?
(To pag e 11-123 )
Repair shor t i n th e wir e betwee n
th e EC M (B4 ) an d th e gaug e
assembly .
Substitute a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f pre -
scribe d voltag e i s no w available ,
replac e th e origina l ECM .
This signal s th e EC M whe n th e transmissio n is in o r position .
Inspection o f A/ T Gea r Positio nSignal.
Check th e operatio n o f th e A/ T
gea r positio n switch :
1 . Tur n th e ignitio n switc h O N (II) .
2 . Observ e th e A/ T shif t positio n
indicato r an d selec t eac h posi -
tion separately .
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(From pag e 11-122 )
Chec k fo r a n ope n i n th e wir e
(AT F P N line) :
1. Tur n th e ignitio n switc h OFF .2. Reconnec t th e 30 P (C412 ) con -necto r t o th e gaug e assembly .
3 . Reconnec t th e 26 P connecto r
to th e TCM .4. Star t th e engine .
5 . Measur e voltag e betwee n EC M
connecto r terminal s B 4 an d
A26 wit h th e transmissio n inposition .
Is ther e les s tha n 1. 0 V ? Repai
r ope n i n th e wir e
betwee n th e EC M (B4 ) an d th egaug e assembly .Repair ope n i n GR N wir e
betwee n th e gaug e assembl y
an d th e A/ T gea r positio n
switch .
Chec k fo r a n ope n i n th e wir e
(AT P P N line) :
Measur e voltag e betwee n EC M
Connecto r terminal s B 4 an d A2 6
with th e transmissio n i n posi -tion.
Is ther e les s tha n 1.0V ? Repai
r ope n i n GRN/WH T wir e
betwee n th e gaug e assembl y an d
th e A/ T gea r positio n switch .
A/ T gea r positio n signa l i s OK .
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Idle Contro l Syste m
Neutra l Switc h Signa l (M/T )
This signal s th e EC M whe n th e transmissio n is in neutral .
Inspectio n o f neutra l switc h signal .
Chec k fo r a n ope n i n th e wir e
(NTS W line) :
1. Tur n th e ignitio n switc h O N (II) .2. Measur e voltag e betwee n EC M
connecto r terminal s B 4 an d
A26 .
Is ther e voltage ?
Chec k fo r a shor t i n th e wir e
(NTS W line) :
1. Shif t transmissio n int o gear .2. Measur e voltag e betwee n EC M
connecto r terminal s B 4 an d
A26 .
Is ther e approx . 5 V ?
Neutra l switc h signa l i s OK . I
s ther e voltage ? Replac
e th e neutra l switc h (se e
sectio n 13 ).
Repai r ope n i n th e wir e
betwee n th e EC M (B4 ) an d
th e neutra l switch .
Repai r ope n i n BL K wir e
betwee n th e neutra l switc h
an d G10 1 (locate d a t righ t mid -
dl e o f engine) .
Chec k fo r a shor t i n th e wir e
(NTS W line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e EC M connec -
to r B (16P ) fro m th e ECM .
3 . Disconnec t th e 3 P connecto r
fro m th e neutra l switch .
4 . Chec k fo r continuit y betwee n
EC M connecto r termina l B 4
Is ther e continuity ?Repair shor t i n th e wir e betwee nthe EC M (B4 ) an d th e neutralswitch .
Replac e neutra l switc h (se e
sectio n 13 ).
Substitut e a known-goo d EC M
an d rechec k (se e pag e 11-3 9
fo r immobilize r information) . I f
prescribe d voltag e i s no w
available , replac e th e origina l
ECM.
Chec k fo r a n ope n i n th e wir e
(NTS W line) :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e 3 P connecto r
fro m th e neutra l switch .
3 . Connec t neutra l switc h con -
necto r terminal s No . 1 to No . 3 .
4 . Tur n th e ignitio n switc h O N (II) .
5 . Measur e voltag e betwee n EC M
connecto r terminal s B 4 an d
A26 .
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Clutch Switc h Signa l (M/T )
This signal s th e EC M whe n th e clutc h is engaged .
Inspection o f clutc h switc h signal .
Chec k fo r a n ope n i n th e wir e
(MTCL S line) :
1 . Tur n th e ignitio n switc h O N (II) .
2 . Measur e voltag e betwee n EC M
connecto r terminal s C 4 an d
A26 .
Is voltag e les s tha n 1. 0 V ?
Chec k fo r shor t i n th e wir e
(MTCL S line) :
1 . Depres s th e clutc h pedal .
2 . Measur e voltag e betwee n EC M
connecto r terminal s C 4 an d
A26 .
(To pag e 11-126 ) Chec
k th e clutc h switch :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e 3 P connecto r
fro m th e clutc h switch .
3 . Chec k fo r continuit y betwee n
th e clutc h switc h connecto r
terminal s No . 1 an d No . 3 .
I s ther e continuity ? Adjus
t th e clutc h switch .
Replac e th e clutc h switch .
I s ther e approx . 5 V ? Repai
r ope n in th e wir e betwee n
th e EC M (C4 ) an d th e clutc h
switch.
Repair ope n in BL K wir e betwee n
th e clutc h switc h an d G40 1
(locate d behin d lef t kic k panel) .
Chec
k fo r a n ope n i n th e wir e
(MTCL S line) :
1 . Tur n th e ignitio n switc h O N (II) .
2 . Measur e voltag e betwee n th e
clutc h switc h connecto r termi -
na l No . 1 an d bod y ground .
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