1991 ACURA NSX Service Repair Manual

C228

C318

C404

C405

C406

C412
C425 (A/T)
C439

C446

C458

C464

NOTE: Several different wires have the same color.
They have been given a number suffix to distinguish them (for example YEL/BLK1 and YEL/BLK2 are not the same).
O: Related to PGM-FI SYSTEM

(cont'd)

1

2

4

YEL/BLK

WHT/BLU

BLU/RED
2

BLK
2

4
BLK

BRN/BLK

RED/GRN

BLK
1

2

3

4

5

6
7

8
WHT/BLU

WHT/BLU
BRN/RED

GRN/YEL

YEL/GRN

YEL/RED

BRN/YEL

9
10

12

13

16

YEL/WHT

GRN/WHT (A/T)
BLK/WHT

YEL
YEL

YEL
2

4
5
BLK/BLU

WHT

BLK/YEL

BLU/WHT
WHT/RED

1

2

3

4
PNK

RED/BLK

RED/BLK

RED/BLK

5


BLK
6

BLK

7


YEL/BLK

8

9
YEL/BLK

GRN/BLU
10

12

13
14

15

16

17

18
BLK/YEL

BLK/YEL

BLK/RED (Canada)
GRN/WHT

BLK

BLK

YEL/BLK

YEL/BLK
1

2

3

4

5

6

7

9

10

13

14

15
RED/YEL

BLK/WHT
ORN/WHT

RED/GRN

LT GRN/WHT (A/T)
GRN/YEL (A/T)

LT GRN
(A/T)

RED/BLK

PNK

GRN

YEL

BLK

BLU/WHT
ORN/BLK
16

17

18

19

20

21

22

24

26

27

28


30

BLK/WHT

GRN/RED

GRN/BLK

BLU

GRN/BLU
BRN/BLK (A/T)
YEL/BLK (A/T)

GRN
(A/T)

LT BLU
(A/T)

GRY/WHT (A/T) YEL/BLU (A/T)
WHT/BLU

YEL/GRN

BLU

YEL/RED

2
BLK

BLU/ORN

PNK

2

3
4
6

6

BLK/YEL

WHT/RED
BLK/WHT

WHT/BLK

WHT/RED
BLU

GRN/WHT2

1

2

3

4

5
WHT/BLK

WHT

YEL/BLK

BLU/WHT

ORN
6

7

8

9
LT GRN/BLK

PNK/BLK

BLU/BLK

GRN/RED

RED/GRN
1

2

3

4
5
GRN/BLU

BRN/BLK

GRN/YEL

LT GRN/WHT
BLU/ORN

GRN
7

8

9

10

12
LT BLU

BLK

GRN/BLK

YEL
GRY/WHTProCarManuals.com

System Description
System Connectors [Front Compartment and Under-dash] (cont'd)
C468
C244

C469
C245

FLOOR
WIRE

HARNESS

C523
C408
C524
C407

C521

C522

UNDER-DASH

FUSE

BOX

SIDE

WIRE

HARNESS

FRONT

COMPARTMENT

WIRE HARNESS

UNDER-HOOD

FUSE/RELAY

BOXProCarManuals.com

C468

C469

C521

C522

C523

C524

NOTE: Several different wires have the same color.
They have been given a number suffix to distinguish them (for example YEL/BLK1 and YEL/BLK2 are not the same).
O: Related to PGM-FI SYSTEM
1

2
3

5

6

7

8

9
10

RED/BLU
WHT/YEL
BRN

WHT/YEL
BLK/SLU

BLK

PNK/BLU

WHT/BLU
BLU

BLK/GRN
11

12
13

14

15

16

17

18

19

20
WHT/BLU

BRN/WHT

WHT/BLK

GRN/WHT
GRN/YEL

RED/YEL

BLU/ORN

YEL

WHT/YEL
PNK/BLK
1

2

3

4
5

6

7

9
RED/WHT
YEL/WHT
BLU/WHT

BLU

RED

BRN/BLK

BLK

RED/BLU2

GRY/WHT
10

11

12

13

14

15

16

17

18
BLU/RED
GRN/BLK
ORN/BLU
GRN/WHT

GRY

LT BLU

ORN/RED
ORN/BLK

YEL/RED
2

3

4

5

6

7

8

9

10
BLK/YEL

RED/BLU

GRN/WHT
YEL/BLK GRN/WHT

ORN/YEL

RED/BLU

RED/ORN
11

13

14

16

16

17

18

19

20
RED/BLK

BLK/YEL
GRN/BLU
YEL/WHT

WHT/BLU

BLK

2
BLK/YEL

BLK/WHT
1

2

3

4

5

6

7

8

10
GRN/WHT

BLK

BLU

WHT/BLK

ORN/BLK RED/WHT

WHT
PNK/ORN
YEL/BLU

YEL/BLU
11

12

13

14

15

16

17

18

19

20
BRN/YEL
GRN/RED BLK/WHT
RED/BLU

PNK/WHT

ORN/WHT
BRN/WHT
GRN/BLK

YEL
(M/T)
ORN
2

BLK/YEL

WHT/BLKProCarManuals.com

Troubleshooting

Troubleshooting Guide
NOTE: Across each row in the chart, the systems that could be sources of a symptom are ranked in the order they should be inspected starting with . Find the symptom in the left column, read across to the most likely source, then refer
to the page listed at the top of that column. If inspection shows the system is OK, try the next most likely system , etc.
If codes other than those listed above are indicated, count the number of blinks again. If the Malfunction Indicator
Lamp is in fact blinking these codes, substitute a known-good ECM and recheck. If the indication goes away, replace
the original ECM.
If the Malfunction Indicator Lamp is on while the engine is running, jump the service check connector. If no code
is displayed (Malfunction Indicator Lamp stays on steady), the back-up system is in operation.
Substitute a known-good ECM and recheck. If the indication goes away, replace the original ECM.
USA:

Malfunction
Indicator
Lamp (MIL)
CANADA:

Check

Engine

Light

PAGE

SYSTEM

SYMTOM
MALFUNCTION INDICATOR
LAMP"

TURNS ON

MALFUNCTION
INDICATOR LAMP BLINKS
ENGINE WON'T START
DIFFICULT TO START
ENGINE WHEN COLD
WHEN COLDFAST IDLE

OUT OF SPEC

IRREGULAR

IDLING
ROUGH IDLE
WHEN WARM

RPM

TOO HIGH
WHEN WARM
RPM

TOO LOW

WHILE
WARMING UP

FREQUENT

STALLING
AFTER

WARMING UP
MISFIRE OR

ROUGH

RUNNING

POOR
PERFORM-

ANCE
FAILS

EMISSION

TEST

LOSS OF

POWER
ENGINE

CONTROL

MODULE

11-42

HEATED

OXYGEN

SENSOR

11-48, 11-50
MANIFOLD
ABSOLUTE

PRESSURE
SENSOR

11-58
CRANKSHAFT

POSITION/
CYLINDER

POSITION
SENSOR

11-64

PGM-FI

ENGINE

COOLANT

TEMPERA-
TURE

SENSOR
THROTTLE
POSITION
SENSOR
INTAKE AIR
TEMPERA-

TURE

SENSOR
BAROMET-

RIC PRES-
SURE

SENSOR
IGNITION

OUTPUT

SIGNAL
VARIABLE VALVE

TIMING & VALVE

LIFT ELECTRONIC
CONTROL SOLENOID
VALVE

6-15

11-74

11-72
11-70

11-68
11-66
ProCarManuals.com

PGM-FI
VARIABLE VALVE
TIMING & VALVE

LIFT ELECTRONIC CONTROL PRES- SURE SWITCH VEHICLE

SPEED

SENSOR IGNITION

TIMING

ADJUSTER
KNOCK

SENSOR
A/T FI

SIGNAL A
A/T Fl

SIGNAL B
IDLE AIR
CONTROL VALVE
OTHER

IDLE

CONTROLS
FUEL

INJECTOR
FUEL

METERING
OTHER

FUEL
SUPPLY INTAKE

AIR
EXHAUST

GAS

RECIRCU-
LATION

CONTROL
SYSTEM

EMISSION CONTROL

OTHER

EMISSION
CONT-

ROLS

11-141

11-145

11-127

11-104

11-116

11-54,11-56

11-107

11-84

11-88

11-82

11-82

11-80

11-78

11-76
6-17('91-'93)
IDLE CONTROL
FUEL SUPPLY
FUEL

PUMPProCarManuals.com

Troubleshooting
Self-diagnostic Procedures
I. When the Malfunction Indicator Lamp (MIL) has been reported on, do the following: 1. Connect the Service Check Connector terminals with a jumper wire as shown (the Service Check Connector islocated under the dash on the passenger side of the car). Turn the ignition switch ON.
SERVICE CHECK CONNECTOR (2P)

JUMPER
WIRE

2. Note the Diagnostic Trouble Code (DTC): the MIL indicates a code by the length and number of blinks. The MIL
can indicate any number of simultaneous component problems by blinking separate codes, one after another. Codes
1 through 9 are indicated by individual short blinks. Codes 10 through 59 are indicated by a series of long and
short blinks. The number of long blinks equals the first digit, the number of short blinks equals the second digit.
USA:
MALFUNCTION

INDICATOR

LAMP
(MIL) CANADA:

CHECK

ENGINE

LIGHT

See DTC 1

See DTC 3

See DTC 13

See DTC 1 and 3

See DTC 3 and 4

See DTC 3 and 14ProCarManuals.com

II. ENGINE CONTROL MODULE (ECM) Reset Procedure

1. Turn the ignition switch off.

2. Remove the CLOCK (7.5 A) fuse from the under-hood fuse/relay box for 10 seconds to reset ECM.

NOTE: Disconnecting the CLOCK fuse also cancels the radio preset stations and the clock setting. Make note of

the radio presets before removing the fuse so you can reset them.

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

1. Remove the Jumper Wire.

NOTE: If the Service Check Connector is jumped, the MIL will stay on.

2. Do the ECM Reset Procedure.

3. Set the radio preset stations and the clock setting.

(cont'd)
CLOCK

(7.5 A) FUSE

UNDER-HOOD

FUSE/RELAY BOXProCarManuals.com

Troubleshooting

Self-diagnostic Procedures (cont'd)

If codes other than those listed above are indicated, verify the code. If the code indicated is not listed above, replace

the
ECM.
The Malfunction Indicator Lamp (MIL) may come on, indicating a system problem, when, in fact, there is a poor or
intermittent electrical connection. First, check the electrical connections, clean or repair connections if necessary.
A/T: The MIL and D indicator light may come on simultaneously when the code blinks 6, 7 and 17. Check the PGM-FI
system according to the PGM-FI system troubleshooting, then recheck the D indicator light. If it comes on, see page 14-52.
The MIL and TCS indicator light may come on simultaneously when the code blinks 3, 5, 6, 13, 15, 16, 17, 35 and

36.
Check
the
PGM-FI system according
to the
PGM-FI system
troubleshooting,
then
recheck
the TCS
indicator
light.
If it comes on, see page 19-84.
The MIL does not come on when there is a malfunction in the A/T Fl signal. However, when the two terminals of
the service check connector are connected with a jumper wire, the MIL will indicate the codes.
PAGE

11-42

11-48 11-48

11-58

11-64

11-66

11-68
11-64
11-70
11-145

11-72

11-88
11-74
11-107
11-76

11-78

6-15

6-17

11-80

11-82

11-82

19-100
19-102
11-50
11-50 11-54
11-54
11-56

11-56

11-116
6-15
6-17
11-80
11-64
11-64ProCarManuals.com