1991 ACURA NSX cruise control

PGM-FI System

System Description

PGM-FI System

The PGM-FI system on this model is a sequential multiport fuel injection system.

Fuel Injector Timing and Duration

The ECM contains memories for the basic discharge durations at various engine speeds and manifold pressures. The

basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors

to obtain the final discharge duration.

Throttle Valve Control

The ECM controls the throttle valve control motor based on accelerator pedal position, TCS control unit and various sig-

nals. The ECM also controls the idle control function, cruise control function, and other functions with the throttle valve

control.

Ignition Timing Control

• The ECM contains memories for basic ignition timing at various engine speeds and manifold pressures. Ignition timing

is also adjusted for engine coolant temperature.

• A knock control system is also used. When detonation is detected by the knock sensor (KS), the ignition timing is

retarded.

Other Control Functions

1. Starting Control

When the engine is started, the ECM provides a rich mixture by increasing fuel injector duration.

2. Fuel Pump Control

• When the ignition switch is initially turned on, the ECM supplies ground to the PGM-FI main relay that supplies

current to the fuel pump for two seconds to pressurize the fuel system.

• When the engine is running, the ECM supplies ground to the PGM-FI main relay that supplies current to the fuel pump.

• When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relay which cuts

current to the fuel pump.

• Excellent engine performance is achieved through the use of VTEC (Variable Valve Timing and Valve Lift Electronic

Control System), intake air bypass control and discharge volume control of the fuel pump.ProCarManuals.com

Drive B y Wir e Syste m
System Descriptio n
Cruise Contro l Functio n
Th e EC M control s th e throttl e valv e contro l moto r t o maintai n th e se t spee d whe n th e cruis e contro l syste m is operating .
Th e throttl e valv e contro l moto r take s th e plac e o f th e cruis e contro l actuator .
Tractio n Contro l Syste m (TCS ) Functio n
I f whee l spi n occur s durin g acceleratio n o r cornering , th e TC S contro l uni t request s th e EC M to reduc e th e engin e powe r
b y retardin g th e ignitio n timin g an d closin g th e throttl e valve . I f th e wheel s loc k during deceleration , th e TC S contro l uni t
signal s th e EC M to ope n th e throttl e valve .
Engin e Protectio n Functio n
Whe n th e engin e spee d exceed s 8,00 0 rp m (M/T ) o r 7,50 0 rp m (A/T) , th e EC M control s th e throttl e valve , regardles s o f th e
accelerato r position , t o protec t th e engin e fro m over-revving .
Fail-saf e Functio n
O n thi s system , th e EC M monitor s th e positio n o f th e accelerato r peda l wit h a dua l circui t typ e accelerato r positio n sensor ,
an d monitor s th e operatio n o f th e throttl e valv e contro l moto r wit h a Throttl e Positio n (TP ) sensor .
Whe n a n abnormalit y occur s i n th e system , th e EC M restrict s th e operatio n o f th e throttl e valv e contro l moto r t o allo w th e
engin e t o continu e t o run .
ProCarManuals.com

Steering Wheel

Removal

7. Disconnect the connectors from the horn and cruise

control set/resume switches, then remove the cable

reel connector from its clips.

CRUISE CONTROL

SET/RESUME SWITCHES

4P CONNECTOR

HORN

CONNECTOR

CABLE

REEL

CONNECTOR
8. Remove the steering wheel nut.

9. Remove the steering wheel by rocking it slightly

from side-to-side as you pull steadily with both

hands.

STEERING WHEEL

NUT

Replace.ProCarManuals.com

Installation

NOTE: Before installing the steering wheel, make sure

the front wheels are straight ahead.

CAUTION:

• Be sure to install the harness wires so that they are

not pinched or interfering with other car parts.

• Do not replace the original steering wheel with any

other design, since it will make it impossible to prop-

erly install the airbag. (Use only genuine Honda

replacement parts.)

• After reassembly, confirm that the wheels are still

straight ahead and that steering wheel spoke angle

is correct. If minor spoke angle adjustment is neces-

sary, adjust the tie-rods only. Do not remove and

reposition the steering wheel.

Confirm that the airbag assembly is securely

attached to the steering wheel; otherwise, severe per-

sonal injury could result during later airbag deploy-

ment.

1. Before installing the steering wheel, center the

cable reel.

Do this by first rotating the cable reel clockwise

until it stops.

Then rotate it counterclockwise (approximately two

turns) until:

— The yellow gear tooth lines up with the mark on

the cover.

— The arrow on the cable reel label points straight

up.

ARROW MARK

CABLE REEL

YELLOW GEAR TOOTH

ALIGNMENT MARK
2. Install the steering wheel.

NOTE: Be sure the steering wheel shaft engages

the cable reel.

STEERING WHEEL

NUT

Replace.

50 N-m

(5.0 kg-m, 36 Ib-ft)

PIN

3. Insert the cruise control set/resume 4P connector

and airbag 3P connector to the steering wheel clips.

4. Connect the horn connector.

CRUISE CONTROL

SET/RESUME SWITCHES

4P CONNECTOR

HORN

CONNECTOR

CABLE REEL

CONNECTOR
PINProCarManuals.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

Cruise Control

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 ser-

vice.

BRAKE SWITCH

Test, page 23-308 ('93-'96) ('91-'92) INDICATOR LIGHT and
DIMMIN
G
CIRCUIT

(In tha gauge assembly)
Bulb Locations, page 23-128
('94-'96) ('91-'93)
MAIN SWITCH

Test, page 23-306 Replacement, page 23-305

SET/RESUME SWITCH

Test, page 23-307 ('93-'96) ('91-'92)
Replacement, page 23-307('93-'96) ('91-'92)
A/T GEAR POSITION

SWITCH

Test, 23-309 ('93-'96) ('91-'92) Replacement, page 23-161 ('93-'96) ('91-'92)

CABLE REEL

Test, page 23-250
Replacement, see section 24
CLUTCH SWITCH (M/T)
Test, page 23-308 ('93-'96) ('91-'92)ProCarManuals.com

Cruise Control

Description

The cruise control system uses mechanically and electri-

cally operated devices to maintain vehicle speed at a

setting selected by the driver.

The ECM receives command signals from the cruise con-

trol main switch and the cruise control set/resume switch.

It receives information about operating conditions from

the brake switch, vehicle speed sensor (VSS), the clutch

switch (with manual transmission), or the A/T gear posi-

tion switch (with automatic transmission). The ECM

sends operational signals to the devices that regulate the

throttle position. The throttle position maintains the

selected vehicle speed. Essentially, the ECM compares

the actual speed of the vehicle to the selected speed.

Then, it uses the result of that comparison to open or

close the throttle.

The brake switch releases the system's control of the

throttle at the instant the driver depresses the brake

pedal. The switch sends an electronic signal to the ECM

when the brake pedal is depressed; the ECM responds

by allowing the throttle to close. The clutch switch (man-

ual transmission) or the A/T gear position switch (auto-

matic transmission) sends a disengage signal to the

ECM that also allows the throttle to close.
Operation:

The cruise control system will set and automatically

maintain any speed above 25 mph (45 km/h). To set,

make sure that the main switch is in the "ON" position.

After reaching the desired speed, press the set switch.

The ECM will receive a set signal and, in turn, will actu-

ate the throttle valve control motor. When the set switch

is depressed and the cruise control system is on, the

"cruise control" ON indicator in the gauge assembly will

light up. You can cancel the cruise control system by

pushing the main switch to "OFF". This erases the set

speed from memory. If the system is disengaged tem-

porarily by the brake switch, clutch switch, or A/T gear

position switch and vehicle speed is still above 25 mph,

press the resume switch. With the resume switch

depressed and the set memory retained, the vehicle

automatically returns to the previous set speed.

For gradual acceleration without depressing the acceler-

ator pedal, push the resume switch down and hold it

there until the desired speed is reached. This will send

an acceleration signal to the ECM. When the switch is

released, the system will be reprogrammed for the new

speed. To slow down, depress the set switch. This will

send a deceleration signal to the ECM causing the car to

coast until the desired speed is reached. When the

desired speed is reached, release the set switch. This

will reprogram the system for the new speed.ProCarManuals.com

Troubleshooting
Cruise Control

NOTE:

• The numbers in the table show the troubleshooting sequence.

• Before troubleshooting:

— Check the No. 5 (15 A) fuse in the under-dash fuse box, and the No. 29 (50 A) and No. 45 (20 A) fuses in the under-

hood fuse/relay box.

— Check that the horns sound.

— Make sure that the headlights go off.ProCarManuals.com