ignition ACURA NSX 1991 Service User Guide

13. Install the fuel injectors and fuel rail assembly in the manifold.

CAUTION: To prevent damage to the O-rings, install the fuel injectors in the fuel rail first, then install them in the

intake manifold.

FUEL

RAILS

FUEL RAIL

INSULATOR

FUEL RAIL
14. Align the center line on the connector with the mark on the fuel rail.

15. Install and tighten the retainer nuts.

16. Connect the fuel hose to the fuel rail.

17. Connect the vacuum hose and fuel return hose to the fuel pressure regulator.

18. Install the connectors on the fuel injectors and the IAT sensor.

19. Install the intake manifold covers.

20. Turn the ignition switch ON (II), but do not operate the starter. After the fuel pump runs for approximately two seconds,

the fuel pressure in the fuel line rises. Repeat this two or three times, then check whether there is any fuel leakage.
MARKINGSProCarManuals.com

System Description

Function and Operation

EPS Control Unit

The control unit receives input signals from the car's speed sensors, torque sensor and rotation sensor. It performs a mul-

titude of control functions, including a circuit which can detect troubles in each functional part of the system and the con-

trol unit itself. The control unit operates the system while the engine is in the process of starting, on receipt of voltage

generated by the alternator. The system remains operational if the engine stalls with the ignition switch in ON (II) position.

Basic Control

(1) Travelling speeds are compiled into data, receiving input signals from the car's speed sensors.

(2) The magnitude and direction of torque are compiled into data, receiving input signals from the torque sensor.

(3) The rotational speed and direction of steering are compiled into data, receiving input signals from the rotation sensor.

(4) Determination of motor torque data from the prescribed assisting force map, based on the car speed data, steering

rotational speed data and the steering torque data.

(5) Changeover of control modes based on data on car speed, direction of torque and rotational direction of steering.

Normal Control Mode:

The rotational direction of motor is determined after changing over to the left/right steering mode in accordance with

torque direction data. The mode is switched to the straight ahead mode when the output data is zero.

Return Control Mode:

According to torque direction data and steering rotational direction data, the mode is changed over to the return control

mode to improve the steering return characteristic.

Damper Control Mode:

According to car speed data, torque value data and steering rotational speed data, the mode is changed over to the

damper control mode to improve the convergence property of the steering.

Rotation sensor
Torque sensor

Steering rotation duty

Unloader duty

(Reduces over-current flow

at full-lock position)

Output duty
Torque duty

Mode changeover

• Normal mode

• Return mode

• Damper mode
Motor control

signal output
Base duty
Car speed sensorsProCarManuals.com

3P CONNECTOR (LEFT SIDE)

WIRE SIDE OF FEMALE TERMINALS
VB: Battery voltage

IG SW: Ignition switch

3P CONNECTOR (RIGHT SIDE)

WIRE SIDE OF FEMALE TERMINALS
VB: Battery voltage

IG SW: Ignition switch

6P CONNECTOR

WIRE SIDE OF FEMALE TERMINALS

4P CONNECTOR

WIRE SIDE OF FEMALE TERMINALS
PULSE UNIT 7P CONNECTOR (MT)

WIRE SIDE OF FEMALE TERMINALSProCarManuals.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

Diagnostic Trouble Code (DTC) Indication

Example:

1.3 seconds
DTC Indication Pattern:

DTC:
11
DTC:
12

EPS Indicator light ON

EPS Indicator light OFF
0.28 seconds

Repeat

Connect the SCS Turn the ignition

service connector switch ON (II)

0.36 seconds 1.3 seconds

• The DTC is indicated by a series of long and short blinks. One long blink equals 10 short blinks.

Add the long and short blinks together to determine the DTC.

• The DTCs are repeated sequentially beginning with the lowest number.

4. Remove the SCS service connector.

NOTE: The Malfunction Indicator Lamp (MIL) will stay on after the engine is started if the SCS service connector is

connected.

5. Remove the CLOCK (7.5 A) fuse in the under-hood fuse/relay box for more than 10 seconds to erase the EPS control

unit memory.ProCarManuals.com

Steering Wheel

Installation

5. Install the airbag assembly with new Torx bolts.

TORX BOLT

10 N-m (1.0 kg-m, 7 Ib-ft)

Replace.

TORX BOLTS

10 N-m (1.0 kg-m, 7 Ib-ft)

Replace.
AIRBAG ASSEMBLY

6. Disconnect the short connector from the airbag 3P

connector.

7. Connect the airbag 3P connector and cable reel 3P

connector.

8. Attach the short connector to the access panel, then

install the access panel on the steering wheel lower

cover.

ACCESS PANEL

SHORT CONNECTOR

(RED)
9. Connect the battery positive terminal, and then con-

nect the negative terminal.

10. After installing the airbag assembly, confirm proper

system operation:

• Turn the ignition to II: the instrument panel SRS

indicator light should come on for about six sec-

onds and then go off.

• Confirm operation of horn buttons.

• Confirm operation of cruise control set/resume

switch.

• Turn the steering wheel counterclockwise and

make sure the yellow gear tooth still lines up

with the alignment mark.

YELLOW GEAR TOOTH

ALIGNMENT MARKProCarManuals.com

Steering Gearbox

Removal/Installation

NOTE: Before removing the steering gearbox, make
sure the front wheels are straight ahead. 1. Remove the steering joint cover.

STEERING JOINT COVER
7. Install the 10 mm hex nut on the balt joint. Be sure
that the 10 mm hex nut is flush with the ball joint
pin end, or the threaded section of the ball joint pin
might be damaged by the ball joint remover.
NOTE: Remove
the
ball
joint
using
the
ball
joint
remover, 28 mm. Refer to page 18-21('93-'96),('91-'92)

for how to use the ball joint remover.
8. Separate the tie-rod ball joint and knuckle using the
special tool.
CAUTION: Avoid damaging the ball joint boot.

NOTE: If necessary, apply penetrating type lubri-

cant to loosen the ball joint.

BALL JOINT REMOVER. 28 mm

07MAC–SL00200

CASTLE NUT

44 N·m (4.4 kg-m, 32 Ib-ft)

10 mm HEX NUT

CLAMP

CLIP
COTTER PIN

Replace.

On reassembly, bend

the cotter pin as shown.

Corrosion resistant bolt/nut

9. Remove the folding spare tire and spare tire holder plate,
10. Disconnect the battery negative terminal, then dis- connect the positive terminal and remove the bat-
tery.

11. Remove the spare tire holder and floor under cover.

FLOOR UNDER

COVER
10 N·m

(1.0kg-m, 7lb-ft)

SPARE TIRE

HOLDER

2, Remove the steering joint bolts, and disconnect the
steering joint by moving the joint toward the col-
umn.
STEERING JOINT

TOOTHED LOCK

WASHERS

STEERING JOINT BOLTS

22 N·m (2.2 kg-m, 16 Ib-ft)

3. Lock the steering shaft with ignition key to keep the steering shaft position.
4. Raise the front of the car, and place safety stands in the proper locations (see section 1).
5. Remove the front wheels.
6. Remove the cotter pin from the castle nut, and remove
the
nut.
8 x
1.25
mm

BOLT

WASHERS

25 N·m

(2.5 kg-m, 18 lb-ft)

Corrosion resistant bolt/nut
(cont'd)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

Diagnostic Trouble Code (DTC):

1. Stop the engine.

2. Disconnect the service check connector from the connector cover located under the glove box.

Connect the two terminals of the service check connector with a jumper wire.

3. Turn the ignition switch on, but do not start the engine.

4. Record the blinking frequency of the ABS indicator light.

The blinking frequency indicates the diagnostic trouble code (DTC).

CAUTION: Before starting the engine, disconnect the jumper wire from the service check connector, or else the

Malfunction Indicator Lamp (MIL) will stay on with the engine running.

NOTE:

• The ABS control unit can indicate three DTCs (one, two or three problems).

• If the ABS indicator light does not light, see Troubleshooting of ABS Indicator Light Circuit page 19-44.

• If you miscount the blinking frequency, turn the ignition switch off, then turn on to blink the ABS indicator light

again.

• After the repair is completed, disconnect the ABS 2,3 (20A) fuse for at least three seconds to erase the ABS

control unit's memory. Then turn the ignition key on again and recheck.

• The memory is erased if the connector is disconnected from the ABS control unit or the ABS control unit is re-

moved from the body.

• After recording the main and sub-code (if applicable), refer to the Symptom-to-System Chart.ProCarManuals.com

Troubleshooting

Self-diagnosis Circuit Check
The Automatic Climate Control System has a built-in self diagnosis feature. To run it, turn the ignition switch ON (II),
then turn the fan speed dial to the AUTO position. Set the temperature control dial to 60° F(18°C), then gradually move

0

th
e
dial up the temperature range to 90°F (32°C). At each temperatu\
re setting, push both the AUTO and OFF burtons
o

n
the control unit at the same time. Wait for at least one minute for the\
system to readjust and check for problems.

If any problems are found in circuits "A" through "I", the system will indicate which circuit has the problem by lighting

the respective indicator light.
NOTE: The climate control unit does not memorize which self-diagnosis indicator lights come on. If you turn the ig-

nition switch OFF, the indicator light memory will be lost.

AUTO BUTTON

OFF BUTTON

TEMPERATURE CONTROL DIAL
TEMP DISPLAY


FAN SPEED DIAL

NOTE:
When you turn the ignition switch OFF, the self-diagnosis function will be canceled. After completing repair work, run the self-diagnosis again to make sure that there are no other malfunctions.COMPONENT WITH PROBLEM
IN-CAR TEMPERATURE SENSOR
OUTSIDE AIR TEMPERATURE

SENSOR

SUNLIGHT SENSOR
HEATER CORE TEMPERATURE

SENSOR

EVAPORATOR TEMPERATURE

SENSOR

AIR MIX CONTROL MOTOR
MODE CONTROL MOTOR
RECIRCULATION CONTROL MOTOR
VENT DOOR CONTROL MOTOR
POSSIBLE CAUSE

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Open or short circuit

Air mix door stuck

Open position signal circuit

Mode door stuck

Open position signal circuit

Open or short circuit

Vent door stuck
Refer to PAGE

22-16

22-1

8

22-20
22-22
22-24
22-2
6
22-28
22-30
22-32
INDICATOR

MODE

A/C
ON
(A/C)

OFF
(A/C)

LED on

defroster

button

A

B

C
D

E

F

G
H
I
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