engine ACURA NSX 1997 Service Repair Manual

Troubleshooting
Engine Contro l Modul e Termina l Arrangemen t (cont'd )
ECM CONNECTO R C (12P )
Wire sid e o f femal e terminal s
ECM CONNECTO R C (12P ) NOTE
: Standar d batter y voltag e is 1 2 V .*: M/ T
Termina l
number
1
2
3
4*
5
6
7
8
9
10
1 1
1 2
Wir e
colo r
YEL/BL K
BLU/BLK
RED/GR N
PNK
BLU
BLK/WH T
ORN
GR N
GRN/YE L
GRN/BLK
YEL/RED
YEL
Termina l nam e
IGP2 (POWE R SOURCE )
ACS (A/ C SWITC H SIGNAL )
PDS W (A/ C PRESSUR E
SWITC H B )
MTCL S (M/ T CLUTC H
SWITCH )
SCS (SERVIC E CHEC K
SIGNAL )
STS (STARTE R SWITC H
SIGNAL )
VSS (VEHICL E SPEE D SEN -
SOR)
NEP (ENGIN E SPEE D
PULSE )
PHRST F (FRON T PEA K
HOLD RESET )
PHRST R (REA R PEA K
HOLD RESET )
MFPLS F (FRON T MISFIR E
PULSE)
MFPLS R (REA R MISFIR E
PULSE)
Descriptio n
Power sourc e fo r th e EC M
contro l circui t
Detect s A/ C switc h signa l
Detect s A/ C pressur e switc h
B signa l
Detect s M/ T clutc h switc h
signa l
Detect s servic e chec k
connecto r signa l (th e signa l
causin g a DT C indication )
Detect s starte r switc h signa l
Detect s VS S signa l
Output s engin e spee d puls e
Send s pea k hol d rese t signa l
Send s pea k hol d rese t signa l
Detect s misfir e puls e
Detect s misfir e puls e
Signa l
With ignitio n switc h O N (II) : batter y
voltage
With ignitio n switc h OFF : 0 V
Wit h A/ C switc h ON : 0 V
Wit h A/ C switc h OFF : approx . 1 0 V
Wit h A/ C pressur e switc h B ON : 0 V
Wit h A/ C pressur e switc h B OFF :
approx . 5 V
Wit h ignitio n switc h O N (II ) an d
clutc h peda l depressed : approx . 5 V
Wit h ignitio n switc h O N (II ) an d
clutc h peda l released : 0 V
Wit h th e connecto r connected : 0 V
Wit h th e connecto r disconnected :
abou t 5 V or batter y voltag e
Wit h starte r switc h ON : batter y
voltag e
With starte r switc h OFF : 0 V
Wit h ignitio n switc h O N (II ) an d rea r
wheel s turning : cycle s 0 - 5 V
Wit h engin e running : pulse s
Wit h engin e running : pulse s
Wit h engin e running : pulse s
Wit h engin e running : pulse s
Wit h engin e running : pulse s
ProCarManuals.com

Terminal Wir enumber colo r
1
2
4
5
6
7
8
9
10
11
1 2
13
1 6
17
1 8
1 9
2 0
WHT/YE L
RED/BLU
YEL/GR N
WHT/RE D
BLU
RED/WH T
RED/YEL
WHT/YE L
YEL/BLU
GRN/BL U
RED/BLK
WHT
GRN
WHT/RE D
BLU/RED
WHT
WHT/BL K
Terminal nam e
VBU (VOLTAG E BAC K UP )
KSR (REA R KNOC K SENSO RKS1)
K-LIN E (DLC )
ALTF (ALTERNATO R F R SIG -NAL)
PTAN K (FUE L TAN K PRES -SURE SENSOR )
ECT (ENGIN E COOLAN T TEM -PERATUR E SENSOR )
IAT (INTAK E AI R TEMPERA -TURE SENSOR )
MAP (MANIFOL D ABSOLUT EPRESSURE SENSOR )
VCC2 (SENSO R VOLTAGE )
SG2 (SENSO R GROUND )
TPS (THROTTL E POSITIO NSENSOR)
KSF (FRON T KNOC K SENSO RKS2)
02S F S (FRON T SECONDAR YOXYGEN SENSOR )
O2S R S (REA R SECONDAR YOXYGEN SENSOR )
O2S F P (FRON T PRIMAR YOXYGEN SENSOR )
O2S R P (REA R PRIMAR Y OXY -GEN SENSOR )
EGRL (EG R VALV E LIF T SEN -SOR)
Decription
Powe r sourc e fo r th e EC M con -trol circui tPower sourc e fo r th e DT C memor y
Detect s knoc k senso r signa l
Send s o r detect s PG M teste r an d
OB D II sca n too l signa l
Detect s alternato r F R signa l
Detect s fue l tan k pressur e senso r
Detect s EC T senso r signa l
Detect s IA T senso r signa l
Detect s MA P senso r signa l
Provide s senso r voltag e
Senso r groun d
Detect s T P senso r signa l
Detect s knoc k senso r signa l
Detect s secondar y oxyge n sen -
so r signa l
Detect s secondar y oxyge n sen -
so r signa l
Detect s primar y oxyge n senso r
signa l
Detect s primar y oxyge n senso r
signal
Detect s EG R valv e lif t senso r
signa l
Signa l
Batter y voltag e a t al l time s
Wit h engin e knocking : pulse s
Wit h ignitio n switc h O N (II) : abou t 5 V
Wit h full y warme d u p engin e running :
0 V - 5 V (dependin g o n electrica l load )
With fue l fil l ca p opened : abou t 2. 5 V
Wit h ignitio n switc h O N (II) : abou t
0. 1 - 4. 8 V (dependin g o n engin e coolan t
temperature )
With ignitio n switc h O N (II) : abou t
0. 1 - 4. 8 V (dependin g o n intak e ai r tem -
perature )
With ignitio n switc h O N (II) : abou t 3 V
Durin g idling : abou t 1. 0 V (dependin g o n
engin e speed )
Wit h ignitio n switc h O N (II) : abou t 5 V
Wit h ignitio n switc h OFF : 0 V
Wit h throttl e full y open : abou t 4. 5 V
Wit h throttl e full y close d wit h full ywarme d u p engine : abou t 0. 5 V
Wit h engin e knocking : pulse s
With throttl e full y opene d wit h full ywarme d u p engine : abov e 0. 6 V
Wit h throttl e quickl y closed : belo w 0. 4 V
Wit h throttl e full y opene d wit h full ywarme d u p engine : abov e 0. 6 V
Wit h throttl e quickl y closed : belo w 0. 4 V
Wit h throttl e full y opene d wit h full ywarme d u p engine : abov e 0. 6 V
Wit h throttl e quickl y closed : belo w 0. 4 V
Wit h throttl e full y opene d wit h full ywarme d u p engine : abov e 0. 6 V
Wit h throttl e quickl y closed : belo w 0. 4 V
Durin g idlin g withou t vacuum : abou t 1.2 V
Wit h 2 7 kP a (20 0 mmHg , 8 in.Hg) : abou t
4.3V
(cont'd )
ECM CONNECTO R D (22P )
ECM CONNECTO R D (22P )
Wire sid e o f femal e terminal s
NOTE: Standar d batter y voltag e is 1 2 V .
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

Troubleshooting

How to Read Flowcharts

A flowchart is designed to be used from start to final repair. It's like a map showing you the shortest distance. But beware:

if you go off the "map" anywhere but a "stop" symbol, you can easily get lost.

Describes the conditions or situation to start a troubleshooting flowchart.

Asks you to do something; perform a test, set up a condition etc.

Asks you about the result of an action, then sends you in the appropriate troubleshooting direction.

NOTE:

The term "Intermittent Failure" is used in these charts. It simply means a system may have had a failure, but it checks

out OK at this time. If the Malfunction Indicator Lamp (MIL) on the dash does not come on, check for poor connections

or loose wires at all connectors related to the circuit that you are troubleshooting (see illustration below).

Some of the troubleshooting flowcharts have you reset the Engine Control Module (ECM) and try to duplicate the

Diagnostic Trouble Code (DTC). If the problem is intermittent and you can't duplicate the code, do not continue through

the flowchart. To do so will only result in confusion and, possibly, a needlessly replaced ECM.

"Open" and "Short" are common electrical terms. An open is a break in a wire or at a connection. A short is an acci-

dental connection of a wire to ground or to another wire. In simple electronics, this usually means something won't

work at all. In complex electronics (like ECM's), this can sometimes mean something works, but not the way it's sup-

posed to.

TIGHT

LOOSE
The end of a series of actions and decisions, describes a final repair action and sometimes directs you to

an earlier part of the flowchart to confirm your repair.ProCarManuals.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

Engine Contro l Modul e (ECM )
NOTE: I f thi s sympto m is intermittent , chec k fo r a loos e No . 5 BACK-U P LIGHTS , ALTERNATOR ,
TUR N SIGNAL S (1 5 A ) fus e in th e under-das h fuse/rela y box , a poo r connectio n a t EC M termina l
A7 , o r a n intermitten t ope n in th e BL U wir e betwee n th e EC M (A7 ) an d th e gaug e assembly .
I s th e lo w oi l pressur e ligh t on ?
Tr y t o star t th e engine .
Doe s th e engin e start ?
Chec k fo r a n ope n in th e wir e o r
bulb :
1. Tur n th e ignitio n switc h OFF .2. Connec t th e EC M connecto r
termina l A 7 t o bod y groun d
with a jumpe r wire .3. Tur n th e ignitio n switc h O N (II) .
Is th e MI L on ?
Substitut e a known-goo d ECM ,
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 .
— Repai r shor t i n the wir e
betwee n No . 5 BACK-U P
LIGHTS , ALTERNATOR , TUR N
SIGNAL S (1 5 A ) fus e an d
gaug e assembly .
— Replac e No . 5 BACK-U P
LIGHTS , ALTERNATOR , TUR N
SIGNALS (15 A) fuse.
Chec k fo r a n ope n in th e wire s
(PG lines) :1. Tur n th e ignitio n switc h O N (II) .
2 . Measur e voltag e betwee n
bod y groun d an d EC M con -
necto r terminal s A1 2 an d A2 5
individually .
I s ther e les s tha n 1. 0 V ?
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
th e origina l ECM . Repai
r ope n i n th e wire(s )
betwee n EC M an d G10 1 (locate d
a t intak e manifold ) tha t ha d
mor e tha n 1.0V .
— Repai r ope n i n th e wire s
betwee n EC M (A7 ) an d gaug e
assembly .— Replac e th e MI L bulb .
(cont'd )
Turn th e ignitio n switc h O N (II) .
The Malfunctio n Indicato r Lam p
(MIL ) neve r come s o n (eve n fo r
tw o seconds ) afte r ignitio n i s
turne d O N (II) .
ProCarManuals.com

PGM-FI Syste m
Engine Contro l Modul e (ECM ) (cont'd )
The Malfunctio n Indicato r Lam p
(MIL ) stay s o n o r come s o n afte r
tw o seconds .
Chec k th e Diagnosti c Troubl e
Code (DTC) :1. Connec t a sca n too l o r Hond a
PG M Tester .
2. Tur n th e ignitio n switc h O N (II) .3. Rea d th e DT C wit h th e sca n
too l o r Hond a PG M Tester .
NOTE:• Whe n ther e is n o Diagnosti c Troubl e Cod e (DTC ) stored , th e MI L wil l sta y o n if th e SC S servic e
connecto r i s connecte d an d th e ignitio n switc h i s on .
• I f thi s sympto m is intermittent , chec k for :
— A loos e ACG(S ) (2 0 A ) fus e in th e engin e compartmen t fuse/rela y bo x
— A loos e No . 2 FUE L PUM P SRS 2 (1 5 A ) fus e in th e under-das h fus e bo x
— A n intermitten t shor t i n th e wire betwee n th e EC M (C5 ) an d th e servic e chec k connecto r
— A n intermitten t ope n i n th e wire s betwee n th e EC M (A26 , B14 ) an d th e servic e chec k con -
necto r
— A n intermitten t shor t i n th e wire betwee n th e EC M (A7 ) an d th e gaug e assembl y
— A n intermitten t shor t i n th e wir e betwee n th e EC M (F1 ) an d th e MA P sensor , accelerato r posi -
tion senso r— A n intermitten t shor t i n th e wir e betwee n th e EC M (D10 ) an d th e T P sensor , EG R valv e lif tsenso r— A n intermitten t shor t i n th e wire betwee n th e EC M (F14 ) an d accelerato r positio n senso r
• Se e th e OB D II sca n too l o r Hond a PG M Teste r user' s manual s fo r specifi c operatin g instruc -
tions.
Are an y DTC(s ) indicated ? G
o t o troubleshootin g proce -
dures , (se e pag e 11-38 )
Chec k th e DT C b y MI L indication :
1. Tur n th e ignitio n switc h OFF .2. Connec t th e SC S servic e con -
necto r t o th e servic e chec k
connector .
3. Tur n th e ignitio n switc h O N (II) .
Doe s th e MI L indicat e an y DTC ? —
Repai r ope n o r shor t i n wir e
betwee n the ECM (D4 ) an d
Dat a Lin k Connector .
— G o t o troubleshootin g proce -
dures , (se e pag e 11-38 )
Try t o star t th e engine .
Does th e engin e start ?
Chec k fo r a shor t i n th e wir e
(SC S line) :
1 . Sto p th e engin e an d tur n th e
ignitio n switc h O N (II) .2. Measur e voltag e betwee n th e
EC M connecto r termina l C 5
an d bod y ground . (T
o pag e 11-63 )
I s ther e approx . 5 V ?
(T o pag e 11-63 ) Repai
r shor t t o bod y groun d i n
th e wir e betwee n EC M (C5 ) an d
servic e chec k connector .
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

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

(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 ).
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