1991 ACURA NSX fuse box

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

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 Flowchart

Engine Control Module (ECM)
Malfunction Indicator Lamp (MIL)
never comes on (even for two se-
conds) after ignition is turned on.
Is the low oil pressure light on?

Turn the ignition switch OFF.

Connect the test harness between
the ECM and connectors (see page 11-37).
Connect A13 terminal to body
ground.

Turn the ignition switch ON.
Is the MIL on?

Measure voltage between body
ground and the following termi-
Is there less than 1.0 V?
Substitute a known-good ECM
and recheck. If symptom/indica-
tion goes away, replace the origi-

nal
ECM. Inspect No. 5 (10 A) fuse in the
under-dash fuse box.
Is the fuse OK?
Repair open in YEL wire between
No. 5 (10 A) fuse and gauge as-

sembly.

Replace the MIL bulb.
Repair open in BLU wire be-
tween ECM (A13) and gauge

assembly.

Repair open in wire between ECM
and G101 (located at right middle of engine) that had more than 1.0

V.
Replace the fuse.
G101
(cont'd)

nals individually:

A23,
A24,

A26,
B2.ProCarManuals.com

PGM-FI System

Troubleshooting Flowchart
Engine Control Module (ECM) (cont'd)
Malfunction Indicator Lamp (MIL) stays on after two seconds.

Turn the ignition switch ON.

Connect the service check con-

nector terminals with a jumper

wire.
Does the MIL indicate
any Diagnostic Trouble

Code (DTC)?

Remove the jumper wire from the
service check connector.
Try to start the engine.Did the engine start?
Remove and inspect the ACG (S) (20 A) fuse in the engine compart-
ment fuse/relay box.
Is the fuse OK?
(To page 11-45) Go to self-diagnostic procedures
(see page 11-34).

Turn the ignition switch OFF.

Connect the test harness between

the ECM and connectors (see page 11-37).

Turn the ignition switch ON.
Measure voltage between C9 (+)

terminal and D22 (-) terminal.

Is there approx. 5V (A/T: 11 V)?
Repair short to body ground in
BLU wire between the ECM (C9),
TCM, EPS control unit, ABS con-
trol unit or TCS control unit and service check connector.
Repair open in BLU wire be-
tween ECM (C9) and service check connector.
Repair open in GRN/WHT wire
between service check con-
nector and ECM (D22).
Replace the fuse.
NOTE: After repair, disconnect the service check con-
nector jumper wire, test drive the car, and recheck the
MIL for a code. NOTE: When there is no code stored, the MIL will stay
on if the service check connector is jumped.
Connect the service
check connector termi-

nals with a jumper wire.

Measure voltage be-

tween C9 (+) terminal

and D22 (-) terminal.

Is there approx. 5 V(A/T:
11 V)?

Remove the jumper
wire from the service
check connector.
(To page 11-45)ProCarManuals.com

(From page 11 -44)
Inspect the IG COIL (30 A) fuse

in the engine compartment

fuse/relay box.
Is the fuse OK?

Turn the ignition switch ON.
Disconnect the 3P connector of
each sensor one at a time: MAP sensor

EGR
valve
lift
sensor
Accelerator pedal angle sensor
Does the MIL remain ON?
Connect the service check con-

nector terminals with a jumper

wire.
Disconnect the 3P connector of

each sensor one at a time:
TP sensor
Ignition timing adjuster

Does the MIL indicate
code 7 or 18?

Turn the ignition switch OFF.
Remove the jumper wire from the
service check connector.
Connect the test harness.

Disconnect the "D" connector

from the ECM only, not the engine

wire harness (see page 11-37).

Check for continuity between

body ground and the following

terminals: D19, D20.

(To page 11-46) Replace the fuse.
Substitute a known-good ECM
and recheck. If symptom/indica-
tion goes away, replace the origi-
nal
ECM.
Replace the sensor that caused
the light to go out upon its discon- nection.
Replace the TP sensor or ignition
timing adjuster. (From page 11-44)

Turn the ignition switch
OFF.

Disconnect "A" con-
nector from the ECM.

Turn the ignition switch

ON.
Is the MIL on?

Repair short to body
ground in BLU wire be-

tween the ECM (A13)
and
MIL.

Continuity?

(cont'd)ProCarManuals.com

Idle Control System

Troubleshooting Flowchart

This signals the ECM when the engine is cranking.
Inspection of starter switch
signal.
Connect the test harness be-
tween the ECM and connectors
(see page 11-37).
Measure voltage between C11(+) terminal and A26 (-) terminal

with the ignition switch in the

start position.

Is there battery voltage ?
Starter switch signal is OK.
NOTE:

M/T: Clutch pedal must be depressed. A/T: in or range.
Inspect No. 7 (7.5 A) fuse in the
under-dash fuse box.
Is the fuse OK?
Repair open in BLK/WHT wire
between ECM (C11) and No. 7
fuse. Replace the fuse.

Starter Switch Signal

BATTERY

VOLTAGE?ProCarManuals.com

6. Turn the ignition switch OFF.

7. Reconnect the 2P connector on the IAC valve, then

remove CLOCK fuse in the under-hood fuse/relay

box for 10 seconds to reset ECM.

8. Restart and idle the engine with no-load conditions

in which the headlights, blower fan, rear defogger,

cooling fan, and air conditioner are not operating

for one minute, then check the idle speed.

Idle speed should be:

M/T

A/T
800
50 rpm

750
50 rpm

(in or range)ProCarManuals.com

Fuel Supply System
PGM-FI Main Relay (cont'd)
Troubleshooting Flowchart
(To page 11-123)
BLK/

WHT
GRN/

YEL/
BLK

PGM-FI
MAIN RELAY

BLK/

YEL

BLK

YEL/

BLU

BLK/

YEL

BLK/

YEL
BLK

Engine will not start.
Inspection of PGM-FI main

relay.

Disconnect the PGM-FI main
relay connectors.
Check for continuity between
BLK terminal and body

ground.

Does continuity exist?
Measure the voltage between YEL/BLU terminal and body

ground.

Is there battery voltage?

Turn the ignition switch ON.
Measure the voltage between BLK/YEL terminal and body

ground.

Is there battery voltage?
Measure the voltage between BLK/YEL terminal and body
ground.
Is there battery voltage?
Turn the ignition switch START
position with the clutch pedal
depressed.
Repair open in BLK wire between
the PGM-FI main relay and G101
(located at right middle of
engine).
Replace the ACG(S) (20 A)
fuse in the engine compart-
ment fuse/relay box.
Repair open in YEL/BLU wire
between the PGM-FI main
relay and the ACG(S) (20 A)

fuse.

Replace the No. 2 (15 A) fuse
in the under-dash fuse box.
Repair open in BLK/YEL wire
between the PGM-FI main
relay and the No. 2 (15 A)

fuse.

Replace the IG COIL (30 A)
fuse in the engine compart- ment fuse/relay box.
Repair open in BLK/YEL wire
between the PGM-FI main
relay and the IG COIL (30 A)

fuse.ProCarManuals.com