bulb ACURA NSX 1991 Service Repair Manual

Engine Control Module (ECM)

NOTE: If this symptom is intermittent, check for a loose No. 5 BACK-UP LIGHTS, ALTERNATOR,

TURN SIGNALS (15 A) fuse in the under-dash fuse/relay box, a poor connection at ECM terminal

A7, or an intermittent open in the BLU wire between the ECM (A7) and the gauge assembly.

Is the low oil pressure light on?

Try to start the engine.

Does the engine start?

Check for an open in the wire or

bulb:

1. Turn the ignition switch OFF.

2. Connect the ECM connector ter-

minal A7 to body ground with a

jumper wire.

3. Turn the ignition switch ON (II).

Is the MIL on?

Substitute a known-good ECM,

and recheck. If symptom/indica-

tion goes away, replace the origi-

nal
ECM.
— Repair short in the wire

between No. 5 BACK-UP

LIGHTS, ALTERNATOR, TURN

SIGNALS (15 A) fuse and

gauge assembly.

— Replace No. 5 BACK-UP

LIGHTS, ALTERNATOR, TURN

SIGNALS (15 A) fuse.

ECM CONNECTOR A (26P)

Check for an open in the wires

(PG line):

1. Turn the ignition switch ON (II).

2. Measure voltage between

body ground and ECM connec-

tor terminals A12 and A25 indi-

vidually.
WIRE SIDE OF FEMALE TERMINALS

Is there less than 1.0 V?
Repair open in the wire(s)

between ECM and G101 (located

at intake manifold) that had

more than 1.0V.

— Repair open in the wires

between ECM (A7) and gauge

assembly.

— Replace the MIL bulb.
WIRE SIDE OF FEMALE TERMINALS
ECM CONNECTOR A (26P)
Substitute a known-good ECM

and recheck. If symptom/indica-

tion goes away, replace the origi-

nal
ECM.
Turn the ignition switch ON (II).
The Malfunction Indicator Lamp

(MIL) never comes on (even for

two seconds) after ignition is

turned ON (II).ProCarManuals.com

Troubleshooting Precautions

EPS Indicator Light

Under normal conditions, the EPS indicator light in the gauge assembly comes on when the ignition switch is turned to

the ON (II) position, then goes off after the engine is started. This indicates that the bulb and its circuits are operating cor-

rectly. If there is any trouble in the system, the EPS indicator light turns on during driving, and the power steering assist is

turned off. When the EPS indicator light comes on, the control unit memorizes the DTC. In this case, the control unit does

not activate the EPS system after the engine starts again but it keeps the EPS indicator light on.

Diagnostic Trouble Code (DTC)

• The lowest DTC is indicated first.

• The DTCs continue blinking until the ignition switch is turned off.

• The DTCs are erased from the control unit when the EPS control unit VBU power supply or connector is disconnected.

• The EPS system can be reset and the control unit's memory can be erased by disconnecting the CLOCK (7.5 A) fuse for

more than ten seconds.

Self-diagnosis:

The CPU (central processing unit) controls the following when it detects a problem during self-diagnosis:

1. Turns the EPS indicator light ON to alert the driver.

2. Power assist stops, and normal manual steering operation resumes (except DTC 21 and DTC 33).

3. The EPS control unit memorizes the diagnostic trouble code (DTC).

4. After the DTC is stored in the control unit, the CPU stops self-diagnosis.

Troubleshooting:

• Before starting the troubleshooting, clear the DTC by disconnecting the CLOCK (7.5 A) fuse for ten seconds or more,

and test-drive the car. Check that the symptom of the trouble appears again, and then troubleshoot. If the problem is an

intermittent problem, the system does not become active after the engine starts even though the problem is solved.

• When both EPS indicator light and A/T "D" indicator light come on, perform the A/T troubleshooting first.

• When the customer's reported problem cannot be verified in the car, ask the customer about the conditions when the

EPS indicator light came ON, then test-drive the car under those conditions, if possible. If the EPS indicator light does

not come ON during the test, check for loose connections or poor contacts at the connectors by wiggling the harness,

etc.

• The connector terminal numbers are viewed from the wire side for the female terminals and from the terminal side for

the male terminals.

• After the repair, test-drive the car and check that the EPS indicator light does not come ON again during the test. (Refer

to the Symptom-to-System Chart for diagnostic period.)ProCarManuals.com

Troubleshooting
Anti-lock Brak e Syste m (ABS ) Indicato r Ligh t
Temporar y Drivin g Conditions :
1. Th e AB S indicato r ligh t wil l com e o n an d th e AB S
contro l uni t memorize s th e diagnosti c troubl e cod e
(DTC ) unde r certai n conditions .
NOTE : Th e DT C explaine d o n page s 19-46 .
• Th e tire(s ) adhesio n is los t du e to excessiv e cor -
nerin g speed .
DTC: 5, 5-4 , 5-8 .
• Th e vehicl e lose s tractio n whe n startin g fro m a
stuc k conditio n o n a muddy , snowy , o r sand y
road.
DTC: 4-1 , 4-2 , 4-4 , 4-8 .
• Whe n th e parkin g brak e is applie d fo r mor e tha n
3 0 second s whil e th e vehicl e i s bein g driven .
DTC: 2.
• Th e vehicl e is drive n o n extremel y roug h road .
Th e AB S is OK , i f th e AB S indicato r ligh t goe s
of f afte r th e engin e i s restarted .
2 . I f yo u receiv e a customer' s repor t tha t th e AB S in -
dicato r ligh t sometime s come s on , chec k fo r a DTC .
I f a DT C is stored , refe r t o th e appropriat e trouble -
shootin g (se e pag e 19-46 ). I f n o DT C is stored ,
chec k th e syste m usin g th e AL B checke r t o confir m
whethe r ther e is an y troubl e in th e system . Se e pag e
19-41 .
3. Th e AB S indicato r ligh t wil l com e o n an d th e AB S
contro l uni t wil l stor e a DT C whe n ther e i s insuffi -
cien t batter y voltag e t o th e AB S contro l unit . A n
exampl e woul d b e whe n th e batter y is s o wea k tha t
th e ca r mus t b e jump-started . Afte r th e batter y i s
sufficientl y recharged , th e AB S indicato r ligh t wil l
wor k normall y afte r th e engin e i s stoppe d an d
restarted .
However , afte r rechargin g th e battery , th e DT C
mus t b e cleare d fro m th e AB S contro l unit' s
memor y b y disconnectin g th e AB S 2, 3 (20A ) fus e
fo r a t leas t thre e seconds . AB
S Indicato r Ligh t Circuit :
CAUTION : Us e onl y th e digita l multimete r t o
chec k th e system .
1. Th e indicato r ligh t doe s no t g o o n whe n th e ignitio n
switc h i s turne d on .
Chec k th e followin g items . I f the y ar e OK , chec k
th e AB S contro l uni t connectors .
I f no t loos e o r disconnected , instal l a ne w AB S con -
tro l uni t an d recheck :
• Blow n AB S indicato r ligh t bulb .
• Ope n circui t i n YE L wir e betwee n No . 5 (1 5 A )
fus e an d gaug e assembly .
• Ope n circui t i n BLU/WH T wir e betwee n gaug e
assembl y an d AB S contro l unit .
• Loos e componen t groundin g of the AB S contro l
uni t t o th e body .
2 . Th e AB S indicato r ligh t remain s O N afte r th e engin e
i s started , howeve r th e AB S indicato r ligh t doe s no t
blin k an y cod e o r sub-code . Chec k th e followin g
items :
• Loos e o r poo r connectio n of the wir e harnes s a t
th e AB S contro l unit .
• Fault y AB S 2, 3 (20A ) fuse .
• Ope n circui t i n WHT/BL K wir e betwee n AB S 2, 3
(20A ) fus e an d AB S contro l unit .
• Ope n circui t i n YEL/BL K wir e betwee n fus e No .
4 (1 5 A ) an d AB S contro l unit .
• Shor t circui t i n BLU/WH T wir e betwee n gaug e
assembl y an d AB S contro l unit .
• Ope n circui t i n WHT/BL U wir e betwee n alter -
nato r an d AB S contro l unit .
• Loos e componen t groundin g o f th e AB S contro l
uni t t o th e body .
I f th e proble m is no t found , substitut e a known-goo d
AB S contro l uni t an d rechec k whethe r th e AB S in -
dicato r ligh t remain s ON .
ProCarManuals.com

(From pag e 23-100 )
Turn th e ignitio n switc h off .
Chec k fus e No . 2 (1 5 A) .
I s th e fus e OK ?
Disconnec t th e 4- P connecto r
fro m th e alternator .
Tur n th e ignitio n switc h on .
Chec k fo r voltag e in th e YE L wir e
a t th e IG termina l o f th e 4- P con -
nector .
I s ther e batter y voltage ?
Groun d th e WHT/BL U wire at th e
L termina l o f th e 4- P connector .
Doe s th e chargin g syste m ligh t
com e on ?
Perfor m alternator/regulato r tes t(see pag e 23-102 ).
Replac e th e fuse .
L (WHT/BLU )
IG (YEL )
View fro m
termina l sid e
Repai r ope n i n th e YE L wire .
Check fo r a blow n chargin g
syste m ligh t bulb . I f th e bul b is
OK . repai r ope n in th e WHT/BL U
wire.
ProCarManuals.com

Gauge Assembly

Bulb Locations

GAUGE LIGHTS (1.4W x 2)

SRS INDICATOR LIGHT (1.4 W)

RIGHT TURN SIGNAL INDICATOR LIGHT (1.4 W)

EPS INDICATOR LIGHT (1.4 W)

BRAKE SYSTEM LIGHT (1.4 W)

SEAT BELT REMINDER LIGHT (1.4 W)

TCS INDICATOR

LIGHT (1.96 W)

LOW FUEL INDICATOR

LIGHT (1.4 W)

GAUGE LIGHT

(1.4
W)
HIGH BEAM INDICATOR LIGHT (1.4 W)

LEFT TURN SIGNAL INDICATOR LIGHT (1.4 W)

ABS

INDICATOR LIGHT (1.4 W)

CHARGING SYSTEM LIGHT (1.4 W)

MALFUNCTION

INDICATOR

LAMP (MIL)

(1.4W)

LOW OIL PRESSURE

INDICATOR

LIGHT (1.4 W)

GAUGE LIGHT

(1.4
W)

GAUGE LIGHT

(3.0
W)
GAUGE LIGHT

(3.0
W)
GAUGE LIGHT

(3.0
W)
CRUISE INDICATOR LIGHT

(1.96
W)ProCarManuals.com

Seat Bel t Reminde r Syste m
Seat Bel t Switc h Tes t
1. Slid e th e driver' s sea t al l th e wa y forward , the n dis -
connec t th e 2- P connecto r fro m th e sea t bel t switch .
2 . Chec k continuit y betwee n th e A an d B terminal s wit h
th e driver' s sea t bel t buckle d an d unbuckled .
• Ther e shoul d b e n o continuit y wit h th e driver' s
sea t bel t buckled .
• Ther e shoul d b e continuit y wit h th e sea t bel t un -
buckled .
CENTERBUCKL E
DRIVER' S SEA T
View fro m wir e sid e
Low Fue l Indicato r
Indicator Ligh t Tes t
1. Par k th e ca r o n leve l ground .
D o no t smok e whil e workin g o n th e
fue l system . Kee p ope n flam e awa y fro m th e wor k
area. Drai n fue l onl y int o a n approve d container .
2. Remov e th e drai n bol t fro m th e fue l tank , an d drai n
th e fue l int o a n approve d container .
The n instal l th e drai n bol t wit h a ne w washer .
3. Ad d les s tha n 1 1 (2. 9 U.S . Gal , 2. 4 Imp . Gal ) o f
fue l an d tur n th e ignitio n switc h on . Th e lo w fue l in -
dicato r ligh t shoul d com e o n withi n fou r minutes .
• I f i t does , g o t o ste p 4 .
• I f i t doesn't , g o t o ste p 5 .
4. Ad d 4 o f fue l (1. 1 U.S . Gal , 0.8 8 Imp . Gal) . Th e
ligh t shoul d g o of f withi n fou r minutes .
5 . I f th e ligh t di d no t com e o n i n ste p 3 , remov e th e
rea r bulkhea d pane l behin d th e driver' s seat , the n re -
mov e th e acces s panel , an d disconnec t th e 3- P con -
necto r fro m th e fue l gaug e sendin g unit . Connec t th e
A (BLK ) termina l t o th e C (YEL/BLU ) termina l wit h
a jumpe r wire .
• I f th e ligh t come s on , th e proble m is eithe r th e
sendin g uni t o r it s ground .
• I f th e ligh t doe s no t com e on , th e proble m is a n
ope n in th e C (YEL/BLU ) wir e to th e gaug e assem -
bly , o r n o powe r t o th e gauge , o r a ba d bulb .
ACCES SPANEL
3-P CONNECTO R
B (YEL/WHT )
A (BLK)C (YEL/BLU )
ProCarManuals.com

Safety Indicator

Component Location index

SRS components are located in this area. Review the SRS
component locations, precautions, and procedures in the
SRS section (24) before performing repairs or service.
SAFET
Y
INDICATOR (In the gauge assembly)

Removal, page 23-129 ('93-'96) ('91-'92)

Troubleshooting, page 23-152 ('94-'96) ('91-'93)
Input Test, page 23-150 ('94-'96) ('93) ('91-'92)

CEILING LIGHT

Test, page 23-201
ROOF LOCK SWITCH ( * 1)

Test, page 23-154 ('94-'96) ('91-'93)

PASSENGER'S DOOR SWITCH

Test, page 23-204
HIGH MOUNT BRAKE LIGHT

Test, page 23-211

BRAKE SWITCH

Test, page 23-211

DRIVER'S DOOR SWITCH

Test, page 23-204

ROOF HOLDER SWITCH (* 1)

Test, page 23-155 ('94-'96) ('91-'93)

ENGINE COMPARTMENT LID SWITCH

Test, page 23-325 ('93-'96) ('91-'92)
LEFT BRAKE LIGHT
FAILURE SENSOR

Test, page 23-153
TRUNK LATCH SWITCH

Test, page 23-205
RIGHT BRAKE LIGHT

FAILURE SENSOR

Test, page 23-153

*1: NSX-T (open top) only

Description

Safety Indicator System: LED's are used to indicate when the trunk lid, engine compartment lid, a door, or the roof is not latched, or when a brake
light is faulty, or when the roof is not stored or improperly stored in its holder. The LED's will go on and stay on for about
two seconds after the ignition switch has been turned ON, to show that the system circuit is functioning.

Brake Light Bulb Failure Indicator:

If all brake light bulbs are OK, the indicator light stays off because the ORN/WHT wire is grounded by the two brake light
failure sensors connected in series. With the brake lights off, the ground is provided through the diode, the failure sensor relay coil, and bulb filaments. With the brake light on, all four relays (two in the left sensor, two in the right sensor), con-
nected in series, supply ground. If any of the four bulbs is not working, the chain is broken and the ORN/WHT wire is not
longer grounded. The indicator light comes on.ProCarManuals.com

A/T Gear Position Switch

Replacement

SRS components are located in this area. Review the
SRS component locations, precautions, and procedures
in the SRS section (24) before performing repairs or ser-

vice.

1. Remove the console, then disconnect the 12-P and 2-P connectors from the A/T gear position switch.
SWITCH SLIDER (In )

PIN

A/T GEAR POSITION SWITCH
2. Remove the two position switch mounting bolts. 3. Position the slider on the new switch to as shown

above.
4. Shift the shift lever to , then slip the switch into
position,
5. Attach the switch with the two bolts. 6. Test the switch in the and positions. You
should be able to start the engine with the shift lever in position anywhere in the range of free
play.
7. Connect the 12-P and 2-P connectors, clamp the harness, and install the console. Bulb Replacement
SRS components are located in this area. Review the
SRS component locations, precautions, and procedures in the SRS section (24) before performing repairs or ser-

vice.

1. Remove the gauge assembly (see page 23-126).
2. Disassemble the gauge assembly (see page 23-129

('93-'96) ('91-'92)).

3. Remove the bulb from printed circuit board B.
PRINTED CIRCUIT

BOARD B

BULB (1.12 W)

4. Install the indicator in the reverse order of removal.ProCarManuals.com

5. Disconnect the 18-P and 10-P connectors.

CAUTION: Be careful not to damage the SRS wire

harness.

6. Remove the six screws, then remove the headlight-

turn signal switch assembly.

HEADLIGHT SWITCH

10-P CONNECTOR

18-P CONNECTOR

TURN SIGNAL SWITCH

7. If necessary, remove the turn signal cancel unit and

cancel switch.

TURN SIGNAL

CANCEL UNIT
TURN SIGNAL

CANCEL SWITCH
8. If necessary, remove the headlight switch bulb.

HEADLIGHT SWITCH

BULB (0.91 W)ProCarManuals.com

Retractor Switch Test

1. Remove the retractor switch (see previous page).

2. Check for continuity between the terminals in each

switch position according to the table.

Retractor Switch

RETRACTOR SWITCH

Retractor Switch
Retractor Switch Light Bulb Replacement

1. Remove the retractor switch (see previous page).

2. Turn the bulb 45° counterclockwise to remove it.

RETRACTOR SWITCH

BULB (0.84W)ProCarManuals.com