relay ACURA NSX 1997 Service Owner's Manual

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

(From pag e 11-62 )
Chec k fo r a shor t i n th e wir e (MI L
line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connec -
to r A (26P) .
3. Tur n th e ignitio n switc h O N (II) .
Is th e MI L ON ?Repai r shor t t o bod y groun d i n
th e wir e betwee n th e EC M (A7 )
and MIL .
Substitut e a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
the origina l ECM .
(From pag e 11-62 )
Inspec t ACG(S ) (2 0 A ) fus e i n th e
engin e compartmen t fuse/rela ybox.
Is th e fus e OK ? Repai
r shor t i n th e wir e
betwee n ACG(S ) (2 0 A ) fus e
an d PGM-F I mai n relay .
Replac e ACG(S ) (2 0 A ) fuse .
Inspec t I G COI L (3 0 A ) fus e i n th e
engin e compartmen t fuse/rela ybox.
Is th e fus e OK ? Repai
r shor t i n th e wir e
betwee n I G COI L (3 0 A ) fus e
an d PGM-F I mai n relay .
Replac e IG COI L (3 0 A ) fuse .
Chec k fo r a shor t i n a sensor :
1. Tur n th e ignitio n switc h O N (II) .2. Disconnec t th e 3 P connecto r
o f eac h senso r on e a t time :
• MA P senso r
• T P senso r
• EG R valv e lif t senso r• Fue l tan k pressur e senso r
Doe s th e MI L remai n ON ? Replac
e th e senso r tha t cause d
the ligh t t o g o out .
(To pag e 11-64 )(cont'd )
ProCarManuals.com

PGM-FI Syste m
Engine Contro l Modul e (ECM ) (cont'd )
(From pag e 11-63 )
Chec k fo r a shor t i n th e A P sen -
sor:1. Tur n th e ignitio n switc h OFF .2. Connec t th e SC S servic e con -nector .3. Disconnec t th e A P senso r 3 P
connector .
4. Tur n th e ignitio n switc h O N (II) .
Is DT C P124 6 and/o r P124 7
indicated ?
Chec k fo r a shor t i n th e wire s
(VC C lines) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connec -tor D (22P ) an d F (26P) .3. Chec k fo r continuit y betwee nbody groun d an d EC M con -necto r terminal s D10 , F 1 an dF14 individually .
Is ther e continuity ?
I s ther e batter y voltage ?
Chec k fo r a n ope n i n th e wire s
(L G lines) :
1 . Reconnec t al l senso r connec -
tors .
2 . Reconnec t th e EC M connecto r
D (22P ) F (26P) .3. Tur n th e ignitio n switc h O N (II) .4. Measur e voltag e betwee n
bod y groun d an d EC M connec -
tor terminal s A2 6 an d B 9 indi -vidually .
Is ther e les s tha n 1.0V ?
Substitut e a known-goo d EC Mand rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
th e origina l ECM . Replac
e th e A P sensor .
Repai r shor t t o bod y groun d
in th e wir e betwee n EC M(D10 ) an d throttl e angl e sen -
so r an d EG R valv e lif t sensor .
Repai r shor t t o bod y groun d in
th e wir e betwee n EC M (F1 )and MA P senso r Accelerato r
Positio n senso r o r fue l tan k
pressur e sensor .
Repai r shor t t o bod y groun d in
th e wir e betwee n EC M (F14 )and Accelerato r Positio n sen -sor.
Repai r ope n i n th e wire(s )
betwee n EC M (A13 , C D an d
PGM-F I mai n relay .
Chec k fo r poo r connection s
o r loos e wire s a t th e PGM-F I
mai n relay .
Repai r ope n i n th e wire(s )
between EC M (A26 , B9 ) an dG10 1 tha t ha d mor e tha n 1. 0 V .
ProCarManuals.com

(From pag e 11-118 )
Chec k th e A/ C operation :
1 . Star t th e engine .
2. Tur n th e blowe r switc h ON .3. Tur n th e A/ C switc h ON .
Doe s th e A/ C operate ?
Ai r conditionin g signa l i s OK . Chec
k fo r a n ope n in th e wire :
Momentaril y connec t th e No . 4 ter -
mina l o f th e 4 P connecto r o n th e
A/ C clutc h rela y t o bod y groun d
several times .
Is ther e a clickin g nois e fro m th e
A/ C compresso r clutch ? Se
e ai r conditione r inspectio n (se e
sectio n 22 ).
Repai r ope n in th e wir e betwee n
th e EC M (AS ) an d th e A/ C clutc h
relay.
Is voltag e les s tha n 1. 0 V ? Repai
r ope n i n th e wir e betwee n
th e EC M (C2 ) an d th e A/ C switch .
I
s ther e a clickin g nois e fro m th e
A/ C compresso r clutch ?
Substitute a known-goo d EC M
an d rechec k (se e pag e 11-3 9
fo r immobilize r information) . I f
symptom/indicatio n goe s
away , replac e th e origina l
ECM.See th e ai r conditione r inspec -
tio n (se e sectio n 22 ).
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

Fuel Supply System

System Description

The fuel supply system consists of a fuel tank, in-tank

high-pressure fuel pump, fuel pump relay, fuel pump

resistor PGM-FI main relay, fuel filter, fuel pressure regu-

lator, fuel injectors, injector resistor (A/T), and fuel deliv-

ery and return lines. This system delivers pressure-regu-

lated fuel to the fuel injectors and cuts the fuel delivery

when the engine is not running.ProCarManuals.com

PGM-FI Main Relay

Description

The PGM-FI main relay actually contains two individual

relays.

The relay is located behind the passenger's seat back

panel.

One relay is energized whenever the ignition is on which

supplies the battery voltage to the ECM, power to the

fuel injectors, and power for the second relay.

The second relay is energized for 2 seconds when the

ignition is switched on, and when the engine is running

which supplies power to the fuel pump.

PGM-FI

MAIN RELAY
FUEL PUMP

RESISTOR

FUEL PUMP

FUEL

PUMP

RELAY
Relay Testing

NOTE: If the car starts and continues to run, the PGM-FI

main relay is OK.

1. Remove the PGM-FI main relay.

2. Attach the battery positive terminal to the No. 3*

terminal and the battery negative terminal to the

No. 2* terminal of the PGM-FI main relay. Then

check for continuity between the No. 5* terminal and

No. 2 terminal of the PGM-FI main relay.

If there is continuity, go on to step 3.

If there is no continuity, replace the relay and

retest.

3. Attach the battery positive terminal to the No. 4 ter-

minal and the battery negative terminal to the No.

7* terminal of the PGM-FI main relay. Then check

that there is continuity between the No. 3 terminal

and No. 1 terminal of the PGM-FI main relay.

If there is continuity, go on to step 4.

If there is no continuity, replace the relay and

retest.

4. Attach the battery positive terminal to the No. 1 ter-

minal and battery negative terminal to the No. 2*

terminal of the PGM-FI main relay. Then check that

there is continuity between the No. 5* terminal and

No. 2 terminal of the PGM-FI main relay.

If there is continuity, the relay is OK;

If the fuel pump still does not work, go to

Harness Testing in the next column.

If there is no continuity, replace the relay and

retest.

(cont'd)ProCarManuals.com

(From pag e 11-144 )
Chec k fo r a n ope n i n th e wir e
(IGS W line) :
Measur e voltag e betwee n th e
PGM-F I mai n rela y 4 P connecto r
termina l No . 4 an d bod y ground .
I s ther e batter y voltage ? Replac
e th e I G COI L (3 0 A )
fus e i n th e engin e compart -
men t fuse/rela y box .
Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e I G COI L
(3 0 A ) fuse .
Chec k fo r a n ope n o r shor t i n th e
wir e (ST S line) :
1 . Tur n th e ignitio n switc h t o th e
STAR T (III ) position .
NOTE:• M/T : Clutc h peda l mus t b e
depressed .
• A/T : Transmissio n in o r
position .
2 . Measur e th e voltag e betwee n
th e PGM-F I mai n rela y 8 P con -
necto r termina l No . 3 an d
bod y ground .
I s ther e batter y voltage ?
Replace th e No . 7 STARTE RSIGNAL (7. 5 A ) fus e i n th eunder-das h fus e box .Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e No . 7
STARTE R SIGNA L (7. 5 A ) fuse .
Chec k fo r a n ope n i n th e wir e
(FLR 1 line) :1. Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e EC M connec -
to r A (26P ) fro m th e ECM .
3 . Chec k fo r continuit y betwee n
th e PGM-F I mai n rela y 8 P
connecto r termina l No . 2 an d
EC M connecto r termina l A4 .
I s ther e continuity ? Repai
r ope n in th e wir e betwee n
th e EC M (A4 ) an d th e PGM-F I
mai n relay .
(cont'd )(To pag e 11-146 )
ProCarManuals.com

Fuel Suppl y Syste m
PGM-F I Mai n Rela y (cont'd )
(From pag e 11-145 )
Chec k fo r a n ope n i n th e wire s
(IG P lines) :
1 . Reconnec t th e EC M connecto r
A (26P) .2. Reconnec t th e PGM-F I mai n
rela y 4 P an d 8 P connectors .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n
EC M connecto r terminal s A1 3
an d A12 , an d betwee n C 1 an d
A12 .
Is ther e batter y voltage ? Repai
r ope n i n th e wir e
betwee n th e EC M (A13 , C D
an d th e PGM-F I mai n relay .
Replac e th e PGM-F I mai n
relay.
Check fo r a n ope n in th e ECM :
1 . Tur n th e ignitio n switc h OFF .
2 . Measur e voltag e betwee n
EC M connecto r terminal s A 4
an d A1 2 whe n th e ignitio nswitch i s firs t turne d o n (II ) fo r
tw o seconds .
I s ther e 1. 0 V or less ? Substitut
e a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f pre -
scribe d voltag e i s no w available ,
replac e th e origina l ECM .
Chec k th e PGM-F I mai n rela y
(se e pag e 11-143 ).
ProCarManuals.com

EVAP Control Canister Removal/Installation

1. Remove the air cleaner housing.

2. Remove the engine compartment fuse/relay box

mounting bolts and harness clip.

AIR CLEANER

HOUSING

HARNESS CLIP

3. Remove the EVAP control canister bracket mount-

ing bolts.

4. Disconnect the hoses and connector from the EVAP

control canister.

5. Remove the dust filter from the dust filter bracket.

6. Remove the EVAP control canister and brackets.
EVAP CONTROL

CANISTER

DUST FILTER

BRACKET
EVAP CONTROL

CANISTER

BRACKET

DUST FILTER

7. Install the EVAP control canister in the reverse order

of removal.ProCarManuals.com