1991 ACURA NSX brake sensor

Transmission Assembly

Removal

20. Remove the intermediate shaft heat cover and the intermediate shaft mounting bolts.
21. Pry the intermediate shaft out of the differential. Pull and remove it. NOTE:
• Coat all precision finished surfaces with clean engine oil or grease.
• Tie plastic bags over the driveshaft ends.

Corrosion resistant bolt/nut
INTERMEDIATE SHAFT
SUPPORT BASE
INTERMEDIATE SHAFT INTERMEDIATE SHAFT
HEAT COVER
INTERMEDIATE SHAFT
MOUNTING BOLT
22. Remove the parking brake cable holder and the wheel sensor wire clamp.
23. Remove the bolt, and separate the toe control arm from the side beam (see section 18).
24. Remove the damper fork bolt (see section 18).
25. Remove the bolts, and separate the lower control arm from the side beam. 26. Pry the driveshaft out of the differential. Pull and remove it. NOTE:
• Coat all precision finished surfaces with clean engine oil or grease.
• Tie plastic bags over the driveshaft ends.

Corrosion resistant bolt/nut
DAMPER FORK BOLT SELF-LOCKING NUT

Replace.

TOE CONTROL ARM
WHEEL SENSOR WIRE CLAMP PARKING BRAKE
CABLE HOLDER
FLANGE BOLT
LOWER CONTROL ARM SELF-LOCKING NUTReplace. ADJUSTING

BOLT
ADJUSTING

CAM
SELF-LOCKING NUT

Replace.
SET RING

Replace.ProCarManuals.com

Illustrated Index

The accumulator contains high-pressure nitrogen gas; do not puncture, expose to flame or attempt to
disassemble the accumulator or it may explode; severe personal injury may result.

HYDRAULIC SYSTEM
Relieving Accumulator/line pressure, page 19-62 ('91-'92) ('93-'96)

MASTER CYLINDER
Index/Torque, page 19-12

Inspection, page 19-13

ABS CONTROL UNIT Replacement, page 19-70

BRAKE BOOSTER

Tests, page 19-14 Pushrod clearance adjustment, page 19-15

UNDER-HOOD

RELAY BOX B

UNDER-HOOD
FUSE/RELAY BOX

REAR WHEEL SENSOR

Inspection, page 19-71

Replacement, page 19-72
POWER UNIT
Torque/Inspection, page 19-66
ACCUMULATOR/PRESSURE SWITCHIndex/Torque, page 19-67 FRONT WHEEL SENSOR
Inspection, page 19-71
Replacement, page 19-72
MODULATOR/SOLENOID UNIT

Index/Torque, page 19-63 ('91-'92) ('93-'96)
Solenoid Leak Test, page 19-64 ('91-'92) ('93-'96)
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Anti-lock Brake System (ABS) Description

Features/Construction/Operation

General

In a conventional brake system, if the brake pedal is depressed excessively, the wheels can lock before the vehicle

comes to a stop. In such a case, the stability of the vehicle is reduced if the rear wheels are locked, and maneuverabily of

the vehicle is reduced if the front wheels are locked, creating an extremely unstable condition.

The Anti-lock Brake System (ABS) modulates the pressure of the brake fluid applied to each caliper, thereby preventing

the locking of the wheels, whenever the wheels are likely to be locked due to excessive braking. It then restores normal

hydraulic pressure when there is no longer any possibility of wheel locking.

4-Channel Anti-lock Brake System (ABS) Features

• Increased braking stability can be achieved regardless of changing driving conditions.

• The maneuverability of the vehicle is improved as the system prevents the front wheels from locking.

• When the anti-lock brake system goes into action, kickback is felt on the brake pedal.

• The anti-lock brake system is equipped with a self-diagnosis function. When an abnormality is detected, the ABS in-

dicator light comes on. The location of the abnormality can be diagnosed from the frequency of the system indicator

light display blinks.

• This system has individual control of the front and rear wheels. Braking force is controlled on each of the four wheels

independently, resulting in optimum braking effects on the four wheels.

The system has a fail-safe function that allows normal braking if there's a problem with the anti-lock brake system.

Construction

In addition to the conventional braking system, the anti-lock brake system is composed of: gear pulsers attached to the

rotating part of individual wheels; wheel sensors, which generate pulse signals in correspondence to the revolution of the

gear pulsers; ABS control unit, which controls the working of the anti-lock brake system by performing calculations bas-

ed on the signals from the individual wheel sensors and the individual switches; a modulator unit, which adjusts the

hydraulic pressure applied to each caliper on the basis of the signals received from the ABS control unit; an accumulator,

in which high-pressure brake fluid is stored; a pressure switch, which detects the pressure in the accumulator and

transmits signals to the ABS control unit; a power unit, which supplies the high-pressure working fluid to the ac-

cumulator by means of a pump; a motor relay for driving the power unit; a fail-safe relay, which cuts off the solenoid

valve ground circuit when the fail-safe device is at work; and, an ABS indicator light.ProCarManuals.com

Anti-lock Brake System (ABS) Description

Features/Construction/Operation (cont'd)

ABS Control Unit

The ABS control unit consists of a main function section, which controls the operation of anti-lock brake system, and

sub-function, which controls the pump motor and "self-diagnosis."

1. Main Function

The main function section of the ABS control unit performs calculations on the basis of the signals from each wheel

sensor and controls the operation of the anti-lock brake system by putting into action the solenoid valves in the

modulator unit for each front and rear brake.

2. Sub-Function

The sub-function section gives driving signals to the pump motor and also gives "self-diagnosis" signals, necessary

for backing up the anti-lock brake system.

Self-Diagnostic Function

Since the anti-lock brake system modulates the braking pressure when a wheel is about to lock, regardless of the driver's

intention, the system operation and the braking power will be impaired if there is a malfunction in the system. To prevent

this possibility, at speeds above 6 mph (10 km/h), the self-diagnosis function monitors the main system functions. When

an abnormality is detected, the ABS indicator light comes on.

There is also a check mode of the self-diagnosis system itself: when the ignition switch is first turned on, the ABS in-

dicator light comes on and stays on for a few seconds after the engine starts, to signify that the self-diagnosis system is

functional.

Fail-Safe Function

If an abnormality is detected, the ABS control unit turns off the fail-safe relays and motor relay. In this condition, the

anti-lock brake system is prevented from functioning, yet the basic brake system continues to operate normally.

The ABS Indicator Light Comes On

1. When the fluid pressure pump runs more than 120 seconds.

2. When the parking brake is applied for more than 30 seconds while the vehicle is being driven.

3. When the rear wheel(s) is (are) locked more than a specified time.

4. When the wheel rotation signal is not transmitted due to faulty wire or sensor.

5. When the operation time of the solenoid valve(s) exceeds a predetermined valve, and the ABS control unit finds an

open in the solenoid circuit.

6. When the output signals from both main functions in the ABS control unit are not transmitted to the solenoid

valve(s).ProCarManuals.com

ALB Checke r
Function Tes t
NOTE :
• Th e AL B checke r i s designe d t o confir m prope r
operatio n of the anti-loc k brak e syste m (ABS ) b y
simulatin g eac h syste m functio n an d operatin g con -
dition . Befor e usin g th e checker , confir m tha t th e
anti-loc k brak e syste m (ABS ) indicato r ligh t i s no t in -
dicatin g som e othe r proble m wit h th e system . Th e
light shoul d g o o n whe n th e ignitio n i s firs t turne d o n
an d the n g o of f an d sta y of f on e secon d afte r th e
engin e i s started .
• Th e checke r shoul d b e use d throug h modes ,
1-5, t o
confir m prope r operatio n of the system , i n an y on e
of th e followin g situations :
Afte r replacin g an y AB S component .
Afte r replacin g o r bleedin g th e syste m flui d ( 0
mod e no t necessary) .
Afte r an y bod y o r suspensio n repai r tha t ma y
hav e affecte d th e sensor s o r thei r wiring .
• Th e procedur e fo r mode s
1-5 ar e o n thi s pag e an d
19-42 , mod e 0 (whee l senso r signal ) i s o n pag e
19-43 .
1. Wit h th e ignitio n switc h off , disconnec t th e 6- P in -
spectio n connecto r fro m th e connecto r cove r
locate d unde r th e glov e bo x an d connec t th e 6- P in -
spectio n connecto r t o th e AL B checker .
07HAJ-SG0010Bsee pag e 19- 2 fo r othe r applicabl e checkers .
NOTE: Plac e th e vehicl e o n leve l ground with th e
wheel s blocked , pu t th e transmissio n i n neutra l fo r
manua l transmissio n models , an d i n fo r
automati c transmissio n models .
2 . Star t th e engin e an d releas e th e parkin g brake .
3 . Operat e th e AL B checke r a s follows :
(1 ) Tur n th e Mod e Selecto r switc h t o "1" .
(2 ) Pus h th e Star t Tes t switch :
— Th e tes t i n progres s ligh t shoul d com e ON .
— In on e o r tw o mor e seconds , al l fou r monito r
light s shoul d com e o n (I f no t th e checke r i s
faulty) .
— Th e AB S indicato r ligh t shoul d no t com e O N (I f i t
come s o n th e checke r harnes s t o th e 6- P con -
necto r connectio n i s faulty) .
NOTE : Whe n tes t i n progres s indicato r ligh t ON ,
don't tur n th e Mod e Selecto r switch .
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

Brake Ligh t Failur e Senso r Tes t
1. Firs t mak e sur e th e brak e light s com e o n whe n th e
brak e peda l i s pressed .
• I f al l th e brak e light s com e on , g o t o ste p 2 .
• I f on e o f th e brak e light s doe s no t com e on , chec k
whethe r th e bul b is blown . I f th e bul b is OK , g o
to ste p 2 .
• I f non e of the brak e light s com e on , chec k th e
brak e ligh t circui t.
2 . Ope n th e trun k lid , an d remov e th e tri m pane l tha t
cover s th e righ t taillight . Watc h th e
ligh t i n th e safet y indicato r whe n th e A (WHT/GRN )
wir e o f th e 6- P connecto r i s grounde d an d th e igni -
tion switc h is turne d fro m OF F to O N (II) .
RIGH T FAILUR E SENSO R
6- P CONNECTO R
Vie w fro m wir e sid e
If th e ligh t come s o n an d stay s
on , chec k fo r a n ope n in th e A (WHT/GRN ) wir e
betwee n th e safet y indicato r an d th e righ t failur e
sensor .
If th e ligh t doe s no t sta y on , g o
t o ste p 3 .
3. Watc h th e ligh t a s yo u tur n th e igni -
tion switc h fro m OF F to O N (II) , wit h th e B (GRN )
wire o f th e 6- P connecto r grounde d an d th e brak e
peda l pressed .
If th e ligh t come s o n an d stay s
on, replac e th e righ t failur e sensor .
If th e ligh t doe s no t sta y o n , g o
t o ste p 4 . 4
. Remov e th e rea r tri m pane l tha t cover s th e lef t tail -
light . Watc h th e ligh t a s yo u tur n th e
ignitio n switc h fro m OF F to O N (II) , wit h th e A (GRN )
wire o f th e 6- P connecto r grounde d an d th e brak e
peda l pressed .
LEFT FAILUR E SENSO R
6-P CONNECTO R
View fro m wir e sid e
If th e ligh t come s o n an d stay s
on , ther e is a n ope n in th e A (GRN ) wir e betwee n
th e lef t failur e senso r an d th e righ t failur e sensor .
If th e ligh t doe s no t sta y on , g o
t o ste p 5 .
5. Watc h th e ligh t a s yo u tur n th e igni -
tion switc h fro m OF F to O N (II) , wit h th e B (BLK ) wir e
of th e 6- P connecto r grounde d an d th e brak e peda l
pressed .
• I f th e ligh t come s o n an d stay s
on , replac e th e lef t failur e sensor .
• I f th e ligh t doe s no t sta y on , chec k
fo r a n ope n in th e B (BLK ) wir e betwee n th e lef t
failur e senso r an d ground , an d chec k fo r a poo r
groun d a t G551 .
ProCarManuals.com

Brake Lights

Component Location Index

BRAKE SWITCH
Test, page 23-211

HIGH MOUNT BRAKE LIGHT (LED)
LED Replacement, page 23-212
('94-'96) ('91-'93)

Replacement, page 23-212 ('94-'96) ('91-'93) Test, page 23-211

RIGHT TAILLIGHT
Bul
b
Replacement, page 23-196
Failure Sensor Test, page 23-153
LEFT TAILLIGHT Bulb Replacement, page 23-196 Failure Sensor Test, page 23-153
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