sensor ACURA NSX 1991 Service Repair Manual

Fail-Safe Function:

If the control unit detects an abnormality, it shuts the

traction control system off and causes the TCS in-

dicator light to come on. However if the abnormality is

detected while the TCS is activated, the control unit

first establishes the appropriate wheel spin velocity,

then shuts the system down, thus preventing excessive

wheel spin.

Self-Diagnosis Function:

If the control unit detects an abnormality, it records a

Diagnostic Trouble Code (DTC) which can be used to

diagnose the problem. The DTC is shown at the TCS in-

dicator light when the Service Check connector ter-

minals are connected with a jumper wire.

Steering Angle Detection

Steering angle is detected by the steering angle sensor,

located on the steering column. The sensor uses two

magneto-resistor (MR) elements to determine steering

angle and direction of rotation. When the driver turns

the steering wheel, a magnet in the steering shaft

generates waves in the "MR" elements. These waves

are amplified and converted into signals which the con-

trol unit can interpret as angle and direction of turn.

Vehicle Speed Detection

Wheel rotation speed is detected by the wheel sensors,

located at each wheel. The signals are sent to the con-

trol unit, which compares each wheel's speed and de-

termines whether traction control is required.
MR ELEMENT

WHEEL SENSOR
GEAR PULSER
MR

ELEMENT
INDICATOR LIGHTProCarManuals.com

System Description

Engine Output Control

When the TCS is activated, the control unit signals the throttle actuator, located next to the throttle valve. The throttle

actuator is linked to the throttle valve through a series of reduction gears. Although the accelerator pedal position is

still within the driver's control, the throttle valve is automatically relaxed to achieve optimum traction.
Construction and Function

LOST MOTION SPRING

(INSIDE RETURN SPRING)

THROTTLE VALVE

RETURN SPRINGS

DURING NORMAL DRIVING:

LOST

MOTION

SPRING

THROTTLE

LEVER

THROTTLE

RETURN SPRING
THROTTLE DRUM

THROTTLE

VALVE

THROTTLE ACTUATOR

(STEP MOTOR)
Movement of parts

while accelalator pedal open.

Movement of parts while

TCS is actuated.
DURING TCS ACTUATION:
THROTTLE ACTUATOR

(STEP MOTOR)
THROTTLE POSITION SENSOR
THROTTLE VALVE
THROTTLE DRUM

ACCELERATOR PEDAL

ANGLE SENSOR

TCS THROTTLE

LEVERProCarManuals.com

2. Disconnec t th e 5- P connecto r fro m th e steerin g an -
gl e sensor .
3 . Remov e th e steerin g angl e senso r mountin g bolts ,
the n remov e th e steerin g angl e sensor .
NOTE : Tak e car e no t t o dro p th e adjustin g shi m
use d betwee n th e steerin g angl e senso r an d senso r
mountin g bracket .
CAUTION : Tak e car e no t t o damag e o r dro p th e
steerin g angl e senso r a s it i s sensitive . 2
. Connec t th e 5- P connecto r t o th e steerin g angl e
sensor .
3. Instal l th e steerin g colum n covers .
4 . Perfor m th e steerin g angl e senso r syste m chec k (Se e
pag e 19-96 ).
I f ther e i s a n abnormalty , chec k th e troubleshoot -
in g flowchar t (se e pag e 19-96 ).
NOTE :
Installation :
1. Instal l th e steerin g angl e senso r b y tightenin g 2 bolt s
an d mak e sur e th e adjustin g shi m i s installe d
properly.
CAUTION : D o no t appl y an y greas e o r oi l t o th e ad -
justin g shim .
Removal :
1. Remov e th e steerin g colum n covers .
Electroni c Compornent s
Steering Angl e Senso r Replacemen t
STEERING
ANGL E
SENSO R
BOLTS
There is n o nee d to selec t (replace ) th e shi m whe n
th e steerin g angl e senso r i s replaced .
Us e th e origina l shim .
Selectio n (Replacement ) o f th e adjustin g shi m (fo r
adjustin g th e ai r gap ) i s require d onl y whe n th e
steerin g colum n assembl y (withou t th e sensor ) i s
replaced .
STEERIN GANGLESENSO R
BOLT
S
1 0 N ·m (1. 0 kg-m , 7. 2 Ib-ft )
ADJUSTIN GSHIM
Detec t
part .
ProCarManuals.com

Selection of the adjusting shim for the steering angle sensor air gap adjustment.

NOTE:

The adjustment of the air gap between the steering shaft 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. Adequate air gap can be kept by select-

ing the adjusting shim with the reference number.

Selection of The Adjusting Shim

Reference Number Locations

REFERENCE

NUMBER

STEERING

COLUMN
Adjusting ShimProCarManuals.com

Carpet
Replacement
SRS wire harnesses are routed near the carpet. CAUTION:
Remove:
2. Detach the clips at the front edge (passenger's). 3, Remove the console carpet attaching screw from the heater unit (passenger's).
4. Disconnect the air duct (driver's) and air vent, then remove the carpet hooks from the dashboard inside screws.
DASHBOARD

INSIDE SCREW
CARPET
HOOK
(3)

AIR VENT

AIR DUCT
AIR VENT

CLIPS
FLOOR
CARPET
CONSOLE
CARPET

CONSOLE CARPET LEFT DASH
SENSOR
PASSENGER'S

AIRBAG
RIGHT DASH

SENSOR

SRS
MAIN

HARNESS
SRS UNIT

Side sill pad (See page 20-38) Rear side trim panel (See page 20-38)
Center armrest (See page 20-49)
Center console panel (See page 20-52)

SRS UNIT
SCREW
(cont'd)
Seats (See page 20-39)
Footrest
Under-dash fuse box lid (See page 20-38)
Side sill trim (See page 20-38)

All SRS wiring harnesses are covered with
yellow outer insulation.
Before disconnecting any part of the SRS wire
harness, install the short connectors (see page

23-328).
Replace the entire affected SRS harness assem-
bly if it has an open circuit or damaged wiring.ProCarManuals.com

Dashboard

Component Removal/Installation (cont'd)
SRS wire harnesses are routed near the dashboard. CAUTION:
LEFT DASH
SENSOR PASSENGER'S

AIRBAG
RIGHT DASH
SENSOR

SRS MAIN

HARNESS
SRS UNIT

Center console panel removal:

NOTE:

Disassemble in numbered sequence.
ASHTRAY
CENTER CONSOLE PANEL

Disconnect the

connectors.

SRS
UNIT
Lift up the parking

brake lever.

Installation is the reverse of the removal procedure. NOTE: Make sure the connectors are connected properly.All SRS wiring harnesses are covered with
yellow outer insulation.
Before disconnecting any part of the SRS wire
harness, install the short connectors (see page

23-328).
Replace the entire affected SRS harness assem-
bly if it has an open circuit or damaged wiring.
Take care not to scratch the dashboard, center console panel and related parts.Do not drop the screws inside the dashboard.
Remove the center armrest (see page 20-49), clock and center air vent (see page 20-50).ProCarManuals.com

Dashboard
Component Removal/Installation (cont'd)
SRS wire harnesses are routed near the steering

column.
CAUTION:
All SRS wiring harnesses are covered with
yellow outer insulation.Before disconnecting any part of the SRS wire
harness, install the short connectors (see page
23-328).

Replace the entire affected SRS harness assem-
bly if it has an open circuit or damaged wiring.
NOTE: Take care not to scratch the dashboard,
steering column and related parts.
CAUTION: When prying with a flat tip screw-
driver, wrap it with protective tape or a shop towel
to prevent damage. LEFT DASH
SENSOIR
PASSENGER'S AIRBAG
RIGHT DASH

SENSOR

SRS MAIN HARNESS
SRS UNIT

Drivers:
RETRACTOR SWITCH/DASH
BRIGHTNESS CONTROLLER

INSTRUMENT

PANEL

TCS SWITCH

Disconnect the connectors.

DASHBOARD
BRACE

KNEE

BOLSTER

KNEE BOLSTER

PAD
INSTRUMENT
PANEL

CLIP

KNEE BOLSTER

PAD

Disconnect the

connectors.

DASHBOARD LOWER COVER (Driver's)
Installation is the reverse of the removal procedure. NOTE: Make sure the connectors are connected properly.ProCarManuals.com

Replacement

SRS wire harnesses are routed near the dashboard and

steering column.
CAUTION:All SRS wiring harnesses are covered with
yellow outer insulation.Before disconnecting any part of the SRS wire
harness, install the short connectors (see page
23-328).

Replace the entire affected SRS harness assem-
bly if it has an open circuit or damaged wiring.
LEFT DASH

SENSOR
PASSENGER'S

AIRBAG

RIGHT DASH
SENSOR

SRS MAIN

HARNESS
SRS UNIT

1. To remove the dashboard, first remove the: Seats (See page 20-39('93-'96))
Dashboard lower cover (Driver's) (See page
20-54))

Knee bolster and pad (See page 20-54)
Dashboard brace (See page 20-54)
Center armrest (See page 20-49)

Clock, center air vent and console panel (See

pages 20-50, 51, 52)

Climate control unit and stereo cassette/radio
(See page 20-53)Dashboard lower cover (Passenger's) (See page

20-53)

Glove box lid and glove box (See page 20-53)

2. Lower the steering column (see section 17).
To avoid accidental deployment and NOTE:
Remove the access panel, then remove the
short connector (RED). Disconnect the connec-
tor between the airbag and cable reel, then con- nect the short connector (RED) to the airbag

connector.

AIRBAG
CONNECTOR
CABLE REEL

CONNECTOR
ACCESS PANEL SHORT CONNECTOR

(RED)

Connect the special tool to the cable reel

connector.

CABLE REEL
CONNECTOR
SHORT
CONNECTOR
(RED)

SRS
SHORT CONNECTOR

07MAZ–SP00200

(cont'd)

possible injury always install the short connector
on the airbag connector when the SRS wire
harness is disconnected.ProCarManuals.com

ECM

RADIATOR FAN CONTROL SENSOR

Test, page 23-120
ENGINE COMPARTMENT FAN MOTOR

Test, page 23-118
Replacement, page 23-118
ENGINE COMPARTMENT

FAN RELAY

Wire colors: YEL/BLU
BLK/YEL, WHT/RED,
and WHT/BLU

Test, page 23-119

FAN CONTROL

UNITProCarManuals.com

NOTE: A short to ground in the ORN wire can be caused by a short in any component connected to it.

Vehicle Speed Sensor (VSS) Test
Speedometer does not work.

Inspect No. 2 (15 A) fuse in theunder-dash fuse box before

testing.

Disconnect the 3-P connector at

the
VSS.

Turn the ignition switch ON.

Measure voltage between the
BLK/YEL wire terminal and the
BLK wire terminal in the harness
side of the 3-P connector. Is there battery voltage?
Measure voltage between the
YEL/RED and the BLK wire ter-
minals.
Is there about 5 V?(To next page) Repair open in YEL/RED wire or
short to body ground. View from
terminal side

3-P CONNECTOR

VSS

BLK

Is there continuity?

Repair open BLK/YEL wire, be-

tween the VSS and under-dash
fuse box. Check for continuity between the
BLK terminal and body ground.
Repair open between
the VSS and ground
G101.

(cont'd)ProCarManuals.com