1991 ACURA NSX manual transmission

Oil Seal

Removal

1. Remove the differential assembly.

2. Remove the oil seal from the transmission housing.

OIL SEAL

Replace.
TRANSMISSION

HOUSING

3. Remove the oil seal from the torque converter

housing.

OIL SEAL

Replace.
TORQUE CONVERTER

HOUSINGProCarManuals.com

Bearing Preload

Adjustment

NOTE: If any of the items listed below are replaced, the

bearing preload must be adjusted.

TRANSMISSION HOUSING

TORQUE CONVERTER HOUSING

DIFFERENTIAL

TAPERED ROLLER BEARING and OUTER RACE

75 mm THRUST SHIM

90 mm WASHER

OIL GUIDE RING

1. Remove the bearing outer race and 75 mm thrust

shim from the transmission housing by prying up

on the bearing outer race or by heating the housing

to about 212°F (100°C).

CAUTION: Do not reuse the thrust shim if the

outer race was pried out.

NOTE:

• If the outer race was removed by heating the

case, let the transmission cool to room tempera-

ture before adjusting the bearing preload.

• Do not heat the transmission housing in excess

of 212°F (100°C).

• Replace the bearing with a new one whenever

the outer race is replaced.

• Repeat on the torque converter side.ProCarManuals.com

Electrical Power Steering (EPS)

Outline

The NSX/NSX-T uses an electric motor-driven power steering, which possesses the characteristics best suited for a mid-

engine automobile. This system is a power-assisted steering device, with a motor inside the steering gearbox driven by

the EPS control unit. Its distinctive features are described below:

• Minimized loss of engine horsepower and decreased fuel consumption.

• A linear steering feel and the reduction of kickback.

• The system is compact and lightweight because it requires no complicated hydraulic piping, etc.

ALTERNATOR

TRANSMISSION

CONTROL MODULE (TCM)

EPS CONTROL UNIT

VEHICLE

SPEED SENSOR

PULSE UNIT (MT)

BATTERY

STEERING GEARBOX
STEERING WHEEL

STEERING

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System Description

Major Components

The Electrical Power Steering system is composed of the following major components:

• A steering gearbox that converts rotary operation of the steering wheel into transverse operation via a rack and pinion

mechanism. Steering sensors and an actuating motor are incorporated.

• A control unit that computes the optimum amount of power assistance, taking into account steering torque, steering

speed, and vehicle speed. Self-diagnosis functions are included.

• A power unit that drives the motor according to the signals from the EPS control unit. A current sensor is built in to

give feedback information to the EPS control unit. Two relays shut off the power if a problem in the system occurs.

• The countershaft speed sensor on the automatic transmission or the differential speed sensor on the manual transmis-

sion sends a vehicle speed signal to the EPS control unit. Also the speedometer sends a vehicle speed signal to the EPS

control unit. The two signals are used as a double-check.ProCarManuals.com

Rotation Sensor

The rotation sensor is housed inside the steering gearbox near the pinion. It converts the rotation speed and direction of

steering into voltage signals. The rotation of the steering wheel is transmitted to the pinion, which drives the sensor by

accelerating its speed through the three pieces of transmission the gears. Acting as a kind of direct current generator, the

sensor generates direct current voltage proportionately with the rotational speed of the pinion. When the steering direc-

tion is reversed, the voltage is generated in the opposite direction. No power is generated when driving straight ahead

without turning the steering wheel.

Interface Circuit

The interface circuit is housed inside the steering gearbox near the pinion. It rectifies and amplifies the signals from the

torque sensor and the rotation sensor, and transmits the steering signals to the EPS control unit. A phase compensating

circuit is also built in, which changes the output signals in accordance with the drive signals input from the EPS control

unit.

TRANSMISSION GEARS

INTERFACE CIRCUIT

ROTATION SENSORProCarManuals.com

Steering angle sensor system check

1. Start the engine,
2. Push the TCS switch three times within three seconds.
NOTE: Always maintain the same number of rota-
tions.
3. Turn the steering wheel slowly from left to right more than 1.5 turns.

NOTE:
Start checking after the steering wheel moves at
least 1.5 turns from right to left.
Turn the steering wheel slowly, no faster than
one turn in four seconds.
4. Push the TCS switch twice within three seconds. NOTE: Always maintain the same number of rota-
tions.
5. Return the steering wheel to the left side slowly, and check the number of times the TCS indicator light
flashes after the wheel has moved approximately
one turn.

NOTE:

Start the check from the beginning when the steer-ing wheel moves at least one turn from left to
right, Turn the steering wheel slowly, no faster than one
turn in four seconds.
Standard number of times the TCS indicator light

flashes:
Manual Transmission: 5 times
Automatic Transmission: 2 times
6. If there is an abnormality, check the troubleshooting flowchart (see page 19-98('91-'93)('94-'96)
Selection of the adjusting shims for the steering angle

sensor air gap adjustment

NOTE:

The adjustment of the air gap between the steeringshaft and the steering angle sensor should be carried
out in order to obtain adequate sensor output.
The adjusting shim reference number is stamped on
the steering column. Select the adjusting shims that match the reference number using the table below.
Reference Number Locations

REFERENCE

NUMBER

STEERING

COLUMN
Selection of The Adjusting Shim
Adjusting Shim Parts Number

A:53395–SL0–A01
B: 53396–SL0–A01

C: 53397–SL0–A01
D: 53398–SL0–A01
Thickness

0.1 mm

0.2 mm

0.4 mm

0.7 mm
Color

Yellow
Black

Green

White

Reference Number

1

2

3

4

5

6

7

8
Shim (P/N): (Thickness)
Not used: (0 mm)

A:
(0,1
mm)
B:
(0.2
mm)

A + B:
(0.3
mm)
C:
(0.4
mm)

A + C:
(0.5
mm)

B + C:
(0.6
mm)
D:
(0.7
mm)ProCarManuals.com

Relay and Control Unit Locations

Rear Bulkhead

PGM-FI MAIN RELAY
THROTTLE VALVE CONTROL

MOTOR RELAY

Wire colors: BLK,

YEL/BLK, GRN/RED,

and WHT/BLU
TCS CONTROL UNIT
TRANSMISSION CONTROL

MODULE (TCM) (A/T)

PULSE UNIT (M/T)

DASH LIGHTS

BRIGHTNESS

CONTROL UNIT
FAN CONTROL

UNIT

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- I f th e starte r stil l doe s no t cran k th e engine ,
remov e th e starte r an d diagnos e it s interna l
problems .
- I f th e starte r crank s th e engine , chec k fo r a n
ope n i n th e BLK/WH T wir e an d connector s be -
twee n th e starte r an d ignitio n switch . Chec k th e
ignitio n switch .
On car s wit h automati c transmission , chec k th e
A/ T gea r positio n switc h (neutra l positio n
switch ) an d connector .
O n car s with manua l transmission , chec k th e
starte r cu t relay , clutc h interloc k switc h an d
connectors .
NOTE : Chec k th e No . 2 9 (5 0 A ) fus e an d th e
starte r cu t relay , an d inspec t th e securit y alar m
system .
3 . Chec k fo r wea r o r damage :
Th e starte r shoul d cran k th e engin e smoothl y an d
steadily .
If th e starte r engages , bu t crank s th e engin e er -
ratically , remov e th e starte r motor . Inspec t th e
starter , driv e gea r an d flywhee l rin g gea r fo r
damage .
Check th e driv e gea r overrunnin g clutc h fo r bindin g
or slippin g whe n th e armatur e i s rotated with th e
driv e gea r held . Replac e th e gear s i f damaged .
4 . Chec k crankin g voltag e an d curren t draw :
Voltag e shoul d b e n o les s tha n 8. 5 volts .
Curren t shoul d b e n o mor e tha n 35 0 amperes .
I f voltag e i s to o low , o r curren t dra w to o high ,
chec k for :
• Lo w battery .
• Ope n circui t i n starte r armatur e commutato r
segments .
• Starte r armatur e dragging .
• Shorte d armatur e winding .
• Excessiv e dra g i n engine . 5
. Chec k crankin g rpm :
Engin e spee d durin g crankin g shoul d b e abov e 10 0
rpm .
If spee d i s to o low , chec k for :
Loos e batter y o r starte r terminals .
Excessivel y wor n starte r brushes .
Ope n circui t i n commutato r segments .
Dirt y o r damage d helica l splin e o r driv e gear .
Defectiv e driv e gea r overrunnin g clutch .
6 . Chec k th e starte r disengagement :
Depres s th e clutc h peda l al l th e wa y (M/T ) o r shif t
to positio n (A/T) , tur n th e ignitio n switc h
to "Star t (III) " an d releas e to O N (II) .
The starter drive gea r shoul d disengag e fro m th e
flywhee l rin g gear .
I f th e driv e gea r hang s u p o n th e flywhee l rin g gear ,
check :
• Solenoi d plunge r an d switc h fo r malfunction .
• Driv e gea r assembl y fo r dir t o r damage d over -
runnin g clutch .
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