1997 ACURA NSX ignition

Engine Coolant Refilling and Bleeding

CAUTION: When pouring engine coolant, be sure to

shut the relay box lid and not let coolant spill on the

electrical parts or the paint. If any coolant spills, rinse it

off immediately.

NOTE:

• Perform this maintenance when the engine is cool.

• Before replacing the coolant, turn the ignition ON,

slowly turn the climate control temperature knob to

90° and turn off the ignition. This will allow the

coolant in the heater to drain out with the rest of the

system.
1. Open the hood, the rear window and the engine

cover.

2. Remove the cover protecting the water pipes and

shift cables on the underside of the car.

3. Before removing the expansion tank cap, first

loosen the cap to lower pressure.

CAUTION: Do not remove the expansion tank cap

when engine is hot. The coolant is under pressure

and may blow out and scald you. Open the cap

slowly when the engine is cool.

4. Loosen the drain plug in the bottom of the radiator,

and drain the coolant.

5. Remove the two drain bolts from the water pipes,

and drain the coolant.

WASHERS

Replace.

DRAIN BOLTS

15 N-m (1.5 kgf-m, 11 Ibf-ft)
DRAIN HOLE
DRAIN PLUGProCarManuals.com

Engine Control Module (ECM) Reset Procedure

Either of the following actions, will reset the ECM.

Using the OBD II scan tool or Honda PGM Tester to clear the ECM's memory.

NOTE: See the OBD II scan tool or Honda PGM Tester user's manuals for specific operating instructions.

Turn the ignition switch OFF. Remove the CLOCK (7.5 A) fuse from the under-hood fuse/relay box for 10 seconds.

UNDER-HOOD

FUSE/RELAY BOX
CLOCK

(7.5 A) FUSE

III. Final Procedure (this procedure must be done after any troubleshooting)

1. Remove the SCS Service Connector if it is connected. If the SCS service connector is connected and there are no

DTCs stored in the ECM, the MIL will stay on when the ignition switch is turned on.

2. Do the ECM Reset Procedure.

3. Turn the ignition switch OFF.

4. Disconnect the OBD II scan tool or Honda PGM Tester from the Data Link Connector (16P).

IV. Known-Good ECM Substitution

The ECM is part of the immobilizer system. If you substitute a known-good ECM, the ECM will have a different immo-

bilizer code. In order for the engine to start, you must rewrite the immobilizer code with the Honda PGM Tester.

(cont'd)ProCarManuals.com

Troubleshooting

Engine Control Module Terminal Arrangement

ECM CONNECTOR A (26P)

ECM CONNECTOR A (26P)
Wire side of female terminals

NOTE: Standard battery voltage is 12 V.

Terminal

number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

20

21

22

23

24

25

26
Wire

color

BRN

RED

BLU

BLK/YEL

GRN/BLK

GRN

BLU

RED/BLU

GRY

LTGRN

PNK

BLK

YEL/BLK

YEL

BLK/RED

WHT/BLU

ORN

PNK/BLU

RED/YEL

GRN/RED

ORN/BLK

BRN

BLK

BRN/BLK
Terminal name

INJ1 (No. 1 FUEL INJECTOR)

INJ2 (No. 2 FUEL INJECTOR)

INJ3 (No. 3 FUEL INJECTOR)

VSV (EVAP CONTROL CANIS-

TER VENT SHUT VALVE)

FLR1 (FUEL PUMP RELAY)

ESOL (EGR CONTROL

SOLENOID VALVE)

MIL (MALFUNCTION

INDICATOR LAMP)

ACC (A/C CLUTCH RELAY)

FS02SHTC (FRONT SEC-

ONDARY HEATED OXYGEN

SENSOR HEATER CONTROL)

RS02SHTC (REAR SEC-

ONDARY HEATED OXYGEN

SENSOR HEATER CONTROL)

IGN COIL1 (No. 1 IGNITION

COIL part of IGNITION

CONTROL MODULE)

PG1 (POWER GROUND)

IGP1 (POWER SOURCE)

INJ4 (No. 4 FUEL INJECTOR)

INJ5 (No. 5 FUEL INJECTOR)

INJ6 (No. 6 FUEL INJECTOR)

2WBS (EVAP BYPASS

SOLENOID VALVE)

IABCS (IAB CONTROL

SOLENOID VALVE)

PCS (EVAP PURGE CONTROL

SOLENOID VALVE)

FP02SHTC (FRONT PRIMARY

HEATED OXYGEN SENSOR

HEATER CONTROL)

RP02SHTC (REAR PRIMARY

HEATED OXYGEN SENSOR

HEATER CONTROL)

IGN COIL2 (No. 2 IGNITION

COIL part of IGNITION

CONTROL MODULE)

PG2 (POWER GROUND)

LG1 (LOGIC GROUND)
Description

Drives No. 1 fuel injector

Drives No. 2 fuel injector

Drives No. 3 fuel injector

Drives EVAP control canister vent

shut valve

Drives fuel pump relay

Drives EGR control solenoid

valve

Drives MIL

Drives A/C clutch relay

Drives front secondary heated

oxygen sensor heater

Drives rear secondary heated

oxygen sensor heater

Sends ignition pulse

Ground for the ECM power circuit

Power source for the ECM control

circuit

Drives No. 4 fuel injector

Drives No. 5 fuel injector

Drives No. 6 fuel injector

Drives EVAP bypass solenoid

valve

Drives IAB control solenoid valve

Drives EVAP purge control

solenoid valve

Drives front primary heated

oxygen sensor heater

Drives rear primary heated

oxygen sensor heater

Sends ignition pulse

Ground for the ECM power circuit

Ground for the ECM control

circuit
Signal

With engine running: pulses

With ignition switch ON (II):

battery voltage

0 V for two seconds after turning ignition

switch ON (II), then battery voltage

With EGR operating during driving with

fully warmed up engine: duty controlled

With EGR not operating: battery voltage

With MIL turned ON: 0V

With MIL turned OFF: battery voltage

With compressor ON: 0 V

With compressor OFF: battery voltage

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON: battery voltage

With fully warmed up engine running:

pulses

With ignition switch ON (II): 0 V

With engine running: pulses

Less than 1.0 V at all times

With ignition switch ON (II): battery voltage

With ignition switch OFF: 0 V

With engine running: pulses

With ignition switch ON (II): battery

voltage

With engine speed below 4,800 rpm:

battery voltage

With engine speed above 4,800 rpm: 0 V

With engine running, engine coolant

below 153°F (67°C): battery voltage

With engine running, engine coolant

above 153°F (67°C): 0 V

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON (II): 0 V

With engine running: pulses

Less than 1.0 V at all times

Less than 1.0 V at all timesProCarManuals.com

Terminal

number

1

2

3

4

4*

5

6

7

8

9

10

11

12

13

14

15

16
Wire

color

BLU

RED

BLU/BLK

RED

LTGRN

ORN

WHT

ORN/BLU

BLU/GRN

BRN/BLK

GRY

GRN

BLU

ORN/BLU

WHT/BLU

WHT/BLU

BLU/YEL
Terminal name

VTP SWF (FRONT VTEC

PRESSURE SWITCH)

IGN COIL6 (No. 6 IGNITION

COIL part of IGNITION

CONTROL MODULE)

VTP SWR (REAR VTEC

PRESSURE SWITCH)

ATP PN (A/T GEAR

POSITION SWITCH)

NT SW (NEUTRAL

SWITCH)

CYP 2P (CYP SENSOR 2 P

SIDE)

CYP 1P (CYP SENSOR 1 P

SIDE)

CKP 2P (CKP SENSOR 2 P

SIDE)

CKP 1P (CKP SENSOR 1 P

SIDE)

LG2 (LOGIC GROUND)

IGN COIL5 (No. 5 IGNITION

COIL part of IGNITION

CONTROL MODULE)

IGN COIL4 (No. 4 IGNITION

COIL part of IGNITION

CONTROL MODULE)

IGN COILS (No. 3 IGNITION

COIL part of IGNITION

CONTROL MODULE)

CYP 2M (CYP SENSOR 2 M

SIDE)

CYP 1M (CYP SENSOR 1 M

SIDE)

CKP 2M (CKP SENSOR 2 M

SIDE)

CKP 1M (CKP SENSOR 1 M

SIDE)
Description

Detects VTEC pressure switch

signal

Sends ignition pulse

Detects VTEC pressure switch

signal

Detects A/T gear position

switch signal

Detects neutral switch signal

Detects CYP sensor 2

Detects CYP sensor 1

Detects CKP sensor 2

Detects CKP sensor 1

Ground for the ECM control

circuit

Sends ignition pulse

Sends ignition pulse

Sends ignition pulse

Ground for CYP sensor 2

Ground for CYP sensor 1

Ground for CKP sensor 2

Ground for CKP sensor 1
Signal

With engine at low rpm: 0 V

With engine at high rpm:

battery voltage

With ignition switch ON (II): 0 V

With engine running: pulses

With engine at low rpm: 0 V

With engine at high rpm:

battery voltage

In or position: 0V

In any other position: approx. 5 V

In neutral position: 0 V

In any other position: approx. 5 V

With engine running: pulses

With engine running: pulses

With engine running: pulses

With engine running: pulses

Less than 1.0 V at all times

With ignition switch ON (II): 0 V

With engine running: pulses

With ignition switch ON (II): 0 V

With engine running: pulses

With ignition switch ON (II): 0 V

With engine running: pulses

(cont'd)
Wire side of female terminals

NOTE: Standard battery voltage is 12 V.

*: M/T
ECM CONNECTOR B (16P)ProCarManuals.com

Troubleshooting

Engine Control Module Terminal Arrangement (cont'd)

ECM CONNECTOR F (26P)
Wire side of female terminals

NOTE: Standard battery voltage is 12 V.

*: M/T

Terminal

number

1

2

3

4

6

7

8

9

10

10*

11

12

13

14

15

16

17

18

19

20

21

22

24
Wire

color

YEL/WHT

GRN/WHT

BRN

RED

GRY

LT

GRN/BLK

LT

GRN/RED

LTGRN

BLU/ORN

BLU/ORN

BLU/BLK

YEL/RED

BLU/RED

YEL/WHT

GRN/WHT

GRN/WHT

RED/WHT

BLU

BLU/YEL

GRN/YEL

LT GRN/YEL

WHT/YEL

RED/BLU
Terminal name

VCC1

(SENSOR VOLTAGE)

SG1 (SENSOR GROUND)

IMO CODE (IMMOBILIZER

CODE)

FLR2 (FUEL PUMP RELAY 2)

BKSW2 (BRAKE SWITCH 2)

CCRESSW (CRUISE

CONTROL RESUME SWITCH)

CC SETSW (CRUISE

CONTROL SET SWITCH)

CC MSW (CRUISE

CONTROL MAIN SWITCH)

CC ATSSW (CRUISE

CONTROL A/T GEAR

POSITION SWITCH)

CC CLSW (CRUISE

CONTROL CLUTCH SWITCH)

CCIL (CRUISE CONTROL INDI-

CATOR LIGHT)

AP2 (ACCELERATOR

POSITION SENSOR CIRCUIT 2)

AP1 (ACCELERATOR

POSITION SENSOR CIRCUIT 1)

VCC3 (SENSOR VOLTAGE)

SG3 (SENSOR GROUND)

BKSW1 (BRAKE SWITCH 1)

MTSL (REVERSE LOCKOUT

RELAY OUT)

VREF (REFERENCE VOLTAGE)

VT SOLF (FRONT VTEC

SOLENOID VALVE)

VT SOLR (REAR VTEC

SOLENOID VALVE)

ATSDL B (A/T Fl DATA LINE B)

ATSDL (A/T Fl. DATA LINE A)

TCSSDL (TCS DATA LINE)
Description

Provides sensor voltage

Sensor ground

Detects immobilizer signal

Drives fuel pump relay

Detects brake switch 2 signal

Detects resume switch signal

Detects set switch signal

Power source for the cruise

control system

Detects A/T gear position switch

signal

Detects clutch switch signal

Drives cruise control indicator

light

Detects accelerator position

sensor circuit 2 signal

Detects accelerator position

sensor circuit 1 signal

Provides sensor voltage

Sensor ground

Detects brake switch 1 signal

Drives reverse lockout relay

Provides reference voltage to

TCM

Drives front VTEC solenoid

valve

Drives rear VTEC solenoid valve

Detects data from the TCM

Sends data to the TCM

Interface for TCS control unit
Signal

With ignition switch ON (II): about 5 V

With ignition switch OFF: 0 V

With engine at low rpm: battery voltage

With engine at high rpm: 0 V

With brake pedal released and cruise

control main switch ON: battery voltage

With brake pedal depressed: 0 V

With resume switch released: 0 V

With resume switch depressed: battery

voltage

With set switch released: 0 V

With set switch depressed: battery

voltage

With cruise control main switch ON:

battery voltage

With cruise control main switch OFF: 0 V

In , or position: 0 V

In any other position: approx. 8 V

With clutch pedal released: approx. 8 V

With clutch pedal depressed: 0 V

With cruise control ON: 0 V

With cruise control OFF: battery voltage

With accelerator fully open: about 4.5 V

With accelerator fully closed: about 0.5 V

With accelerator fully open: about 4.5 V

With accelerator fully closed: about 0.5 V

With ignition switch ON (II): about 5 V

With ignition switch OFF: 0 V

With brake pedal released: 0 V

With brake pedal depressed: battery

voltage

With vehicle speed above 13 mph

(20 km/h): 0 V

With vehicle speed below 9 mph

(15 km/h): battery voltage

With ignition switch ON (II): about 5 V

With ignition switch OFF: 0 V

With engine at low rpm: 0 V

With engine at high rpm: battery voltage

With engine at low rpm: 0 V

With engine at high rpm: battery voltage

With engine running: pulses

With engine running: pulses

With engine running: pulsesProCarManuals.com

PGM-FI System

System Description (cont'd)

3. Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at

speeds over 1,500 rpm.

Fuel cut-off action also takes place when engine speed exceeds 8,300 rpm, regardless of the position of the throttle

valve, to protect the engine from over-revving.

4. A/C Compressor Clutch Relay

When the ECM receives a demand for cooling from the air conditioning system, it delays the compressor from being

energized, and enriches the mixture to assure smooth translation to the A/C mode.

5. Evaporative Emission (EVAP) Purge Control Solenoid Valve

When the engine coolant temperature is below 153°F (67°C), the ECM controls the EVAP purge control solenoid valve

which cuts vacuum to the EVAP purge control canister diaphragm.

6. Intake Air Bypass (IAB) Control Solenoid Valve

When the engine speed is below 4,800 rpm, the IAB control solenoid valve is activated by a signal from the ECM. Intake

air then flows through the smaller chamber, and high torque is delivered. To increase air flow at engine speeds higher

than 4,800 rpm, the solenoid valve is deactivated by the ECM, and the intake air flows through the larger chamber.

7. Exhaust Gas Recirculation (EGR) Control Solenoid Valve

When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR

control solenoid valve which supplies regulated vacuum to the EGR valve.

ECM Fail-safe/Back-up Functions

1. Fail-Safe Function

When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed

valve for that sensor that allows the engine to continue to run.

2. Back-up Function

When an abnormality occurs in the ECM itself, the fuel injectors are controlled by a back-up circuit independent of the

system in order to permit minimal driving.

3. Self-diagnosis Function [Malfunction Indicator Lamp (MIL)]

When an abnormality occurs in a signal from a sensor, the ECM lights the MIL and stores the diagnostic trouble code

in erasable memory. When the ignition is initially turned on, the ECM supplies ground for the MIL for two seconds to

check the MIL bulb condition.

4. Two Trip Detection Method

To prevent false indications, the Two Trip Detection Method is used for the H02S, fuel metering-related, idle control

system, ECT sensor, EGR system self-diagnostic functions and EVAP control system. When an abnormality occurs,

the ECM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (II)

again, the ECM informs the driver by lighting the MIL.

However, to ease troubleshooting, this function is cancelled when you short the service check connector. The MIL will

then blink immediately when an abnormality occurs.

5. Two (or three) Driving Cycle Detection Method

A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. If misfir-

ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles,

or TWC deterioration is detected during three consecutive driving cycles, the ECM turns the MIL on.

However,
to
ease
troubleshooting,
this
function
is
cancelled when
you
short
the
service check connector.
The MIL
will

then blink immediately when an abnormality occurs.ProCarManuals.com

Drive By Wire System

System Description (cont'd)

Cruise Control Function

The ECM controls the throttle valve control motor to maintain the set speed when the cruise control system is operating.

The throttle valve control motor takes the place of the cruise control actuator.

Traction Control System (TCS) Function

If wheel spin occurs during acceleration or cornering, the TCS control unit requests the ECM to reduce the engine power

by retarding the ignition timing and closing the throttle valve. If the wheels lock during deceleration, the TCS control unit

signals the ECM to open the throttle valve.

Engine Protection Function

When the engine speed exceeds 8,000 rpm (M/T) or 7,500 rpm (A/T), the ECM controls the throttle valve, regardless of the

accelerator position, to protect the engine from over-revving.

Fail-safe Function

On this system, the ECM monitors the position of the accelerator pedal with a dual circuit type accelerator position sensor,

and monitors the operation of the throttle valve control motor with a Throttle Position (TP) sensor.

When an abnormality occurs in the system, the ECM restricts the operation of the throttle valve control motor to allow the

engine to continue to run.ProCarManuals.com

Idle Control System

Starter Switch Signal

This signals the ECM when the engine is cranking.

NOTE:

• M/T: Clutch pedal must be depressed.

• A/T: Transmission in or position.

Is there battery voltage?

Is the fuse OK?
Repair short in the wire

between the ECM (C6) and

the No. 7 STARTER SIGNAL

(7.5 A) fuse or the PGM-FI

main relay.

Replace the No. 7 STARTER

SIGNAL (7.5 A) fuse.
Inspection of Starter Switch Sig-

nal.

Check for an open or short in the

wire (STS line):

Measure voltage between ECM

connector terminals C6 and A26

with the ignition switch in the

start (III) position.

Starter switch signal is OK.

Repair open in the wire between

the ECM
(C6)
and the No. 7

STARTER SIGNAL (7.5 A) fuse.
Inspect the No. 7 STARTER SIG-

NAL (7.5 A) fuse in the under-

dash fuse box.ProCarManuals.com