Nissan Xterra. Manual - part 341

EC-490

< SYMPTOM DIAGNOSIS >

[VQ40DE]

ENGINE CONTROL SYSTEM SYMPTOMS

1 - 6: The numbers refer to the order of inspection.
(continued on next page)

SYSTEM — ENGINE MECHANICAL & OTHER

Knock sensor circuit

2

3

EC-272

Crankshaft position sensor (POS) circuit

2

2

EC-275

Camshaft position sensor (PHASE) circuit

3

2

EC-278

Vehicle speed signal circuit

2

3

3

3

EC-350

Power steering pressure sensor circuit

2

3

3

EC-358

ECM

2

2

3

3

3

3

3

3

3

3

3

EC-361

, 

EC-363

Intake valve timing control solenoid valve cir-
cuit

3

2

1

3

2

2

3

3

EC-165

PNP signal circuit

3

3

3

3

3

EC-369

VIAS control solenoid valve circuit

1

EC-409

Refrigerant pressure sensor circuit

2

3

3

4

EC-482

Electrical load signal circuit

3

EC-461

Air  conditioner  circuit

2

2

3

3

3

3

3

3

3

3

2

HAC-3

ABS actuator and electric unit (control unit)

4

BRC-8

, 

BRC-118

SYMPTOM

Reference 
page

HARD/NO S

TA

R

T/RES

TA

R

T (E

XCP

. HA)

E

N

GINE

 ST

ALL

HES

IT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK KNOC

K

/DET

O

NA

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 IDL

E

/L

OW

 ID

LE

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

S

LOW/NO RETU

RN 

T

O ID

LE

OVERHEA

T

S

/W

A

TER TEMPERA

T

URE HIG

H

E

XCESSIVE

 FUEL CON

S

UMP

T

ION

E

XCESSIVE

 OIL 

C

O

NSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC AD

AE

AF AG AH

AJ

AK

AL

AM HA

ENGINE CONTROL SYSTEM SYMPTOMS

EC-491

< SYMPTOM DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

SYMPTOM

Reference 
page

HARD/NO ST

AR

T/REST

AR

T (EXCP

. 

HA)

E

N

GI

N

E

 ST

AL

L

HESIT

A

TION/S

U

R

GING/F

LA

T SP

OT

SP

ARK KNOCK/DE

T

O

NA

TION

LACK OF POWE

R/POOR

 ACCELERA

TIO

N

HIGH IDL

E/L

OW

 IDL

E

ROUG

H IDLE/HU

NTING

IDL

ING VIBRA

T

ION

SLO

W

/NO RETURN T

O

 IDLE

OVERHEA

T

S/W

A

TE

R

 TEMPERA

T

URE 

HIGH

EXCES

SIVE F

U

EL CONSUMP

T

ION

EXCES

SIVE OI

L CONSUMP

T

IO

N

BA

TTE

R

Y 

DEAD (UN

D

E

R

 CH

A

R

GE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG AH

AJ

AK

AL

AM HA

Fuel

Fuel tank

5

5

FL-6

Fuel piping

5

5

5

5

5

5

FL-5

Vapor lock

—

Valve deposit

5

5

5

5

5

5

5

—

Poor fuel (Heavy weight gasoline, 
Low octane)

—

Air

Air duct

5

5

5

5

5

5

EM-24

Air cleaner

EM-24

Air leakage from air duct
(Mass air flow sensor — electric 
throttle control actuator)

5

5

5

5

EM-24

Electric throttle control actuator

EM-25

Air leakage from intake manifold/
Collector/Gasket

EM-25

, 

EM-28

Cranking

Battery

1

1

1

1

1

1

1

1

PG-4

Generator circuit

CHG-2

, 

CHG-5

Starter circuit

3

STR-3

, 

STR-7

Signal plate

6

EM-112

PNP signal

4

TM-116

Engine

Cylinder head

5

5

5

5

5

5

5

5

EM-112

Cylinder head gasket

4

3

Cylinder block

6

6

6

6

6

6

6

6

4

EM-112

Piston

Piston ring

Connecting rod

Bearing

Crankshaft

EC-492

< SYMPTOM DIAGNOSIS >

[VQ40DE]

ENGINE CONTROL SYSTEM SYMPTOMS

1 - 6: The numbers refer to the order of inspection.

Valve 
mecha-
nism

Timing chain

5

5

5

5

5

5

5

5

EM-59

Camshaft

EM-75

Intake valve timing control

EM-59

Intake valve

3

EM-88

Exhaust valve

Exhaust

Exhaust manifold/Tube/Muffler/
Gasket

5

5

5

5

5

5

5

5

EM-31

, 

EX-

5

Three way catalyst

Lubrica-
tion

Oil pan/Oil strainer/Oil pump/Oil 
filter/Oil gallery/Oil cooler

5

5

5

5

5

5

5

5

EM-34

, 

EM-112

, 

LU-10

, 

LU-

6

Oil level (Low)/Filthy oil

LU-7

Cooling

Radiator/Hose/Radiator filler cap

5

5

5

5

5

5

5

4

5

CO-10

Thermostat

5

CO-26

Water pump

CO-21

Water gallery

CO-28

Cooling fan

5

CO-18

Coolant level (Low)/Contaminat-
ed coolant

5

CO-10

NVIS (NISSAN Vehicle Immobilizer System — 
NATS)

1

1

SEC-3

SYMPTOM

Reference 
page

HARD/NO S

TA

R

T/RES

TA

R

T (E

XCP

. HA)

E

N

GINE

 ST

ALL

HES

IT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK KNOC

K

/DET

O

NA

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 IDL

E

/L

OW

 ID

LE

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

S

LOW/NO RETU

RN 

T

O ID

LE

OVERHEA

T

S

/W

A

TER TEMPERA

T

URE HIG

H

E

XCESSIVE

 FUEL CON

S

UMP

T

ION

E

XCESSIVE

 OIL 

C

O

NSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG AH

AJ

AK

AL

AM HA

NORMAL OPERATING CONDITION

EC-493

< SYMPTOM DIAGNOSIS >

[VQ40DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NORMAL OPERATING CONDITION

Fuel Cut Control (at No Load and High Engine Speed)

INFOID:0000000009484238

INPUT/OUTPUT SIGNAL CHART

*: This signal is sent to the ECM through CAN communication line.

SYSTEM DESCRIPTION

If the engine speed is above 1,800 rpm under no load (for example, the shift position is neutral and engine

speed is over 1,800 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies

based on engine speed.

Fuel cut will be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.

NOTE:

This function is different from deceleration control listed under 

EC-23, "System Description"

.

Sensor

Input Signal to ECM

ECM function

Actuator

Park/neutral position (PNP) switch (M/T)
TCM (A/T)

Neutral position

Fuel cut control Fuel injector

Accelerator pedal position sensor

Accelerator pedal position

Engine coolant temperature sensor

Engine coolant temperature

Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)

Engine speed

Wheel sensor

Vehicle speed*