Nissan Xterra. Manual - part 232

EC-54

< SYSTEM DESCRIPTION >

[VQ40DE]

DIAGNOSIS SYSTEM (ECM)

How to Erase DTC and 1st Trip DTC

NOTE:

• If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10

seconds and then turn it ON (engine stopped) again.

• If the DTC is not for A/T related items (see 

EC-78, "DTC Index"

), skip step 1.

1. Erase DTC in TCM. Refer to 

EC-78, "DTC Index"

.

2. Select “ENGINE” with CONSULT.
3. Select “SELF-DIAG RESULTS”.
4. Touch “ERASE”. (DTC in ECM will be erased.)

Freeze Frame Data and 1st Trip Freeze Frame Data

*: The items are the same as those of 1st trip freeze frame data.

DATA MONITOR MODE

NOTE:

The following table includes information (items) inapplicable to this vehicle. For information (items) applicable

to this vehicle, refer to CONSULT display items.

Monitored Item

For reference values of the following items, refer to 

EC-63, "CONSULT Reference Value in Data Monitor

Mode"

.

Freeze frame data 

item*

Description

DIAG TROUBLE 
CODE
[PXXXX]

• The engine control component part/control system has a trouble code, that is displayed as PXXXX. (Refer 

to 

EC-78, "DTC Index"

.)

FUEL SYS-B1

• “Fuel injection system status” at the moment a malfunction is detected is displayed.
• One of in the following made is displayed.

Mode2: Open loop due to detected system malfunction
Mode3: Open loop due to driving conditions (power enrichment, deceleration enleanment)
Mode4: Closed loop - using oxygen sensor(s) as feedback for fuel control
Mode5: Open loop - has not yet satisfied condition to go to closed loop

FUEL SYS-B2

CAL/LD VALUE [%]

• The calculated load value at the moment a malfunction is detected is displayed.

COOLANT TEMP [

°C] 

or [

°F]

• The engine coolant temperature at the moment a malfunction is detected is displayed.

L-FUEL TRM-B1 [%]

• “Long-term fuel trim” at the moment a malfunction is detected is displayed.
• The long-term fuel trim indicates much more gradual feedback compensation to the base fuel schedule than 

short-term fuel trim.

L-FUEL TRM-B2 [%]

S-FUEL TRM-B1 [%]

• “Short-term fuel trim” at the moment a malfunction is detected is displayed.
• The short-term fuel trim indicates dynamic or instantaneous feedback compensation to the base fuel sched-

ule.

S-FUEL TRM-B2 [%]

ENGINE SPEED [rpm] • The engine speed at the moment a malfunction is detected is displayed.

VEHICL SPEED [km/
h] or [mph]

• The vehicle speed at the moment a malfunction is detected is displayed.

ABSOL TH-P/S [%]

• The throttle valve opening angle at the moment a malfunction is detected is displayed.

B/FUEL SCHDL 
[msec]

• The base fuel schedule at the moment a malfunction is detected is displayed.

INT/A TEMP SE [

°C] 

or [

°F]

• The intake air temperature at the moment a malfunction is detected is displayed.

INT MANI PRES [psi]

• Always a certain value is displayed.
• These items are displayed but are not applicable to this model.

COMBUST CONDI-
TION

DIAGNOSIS SYSTEM (ECM)

EC-55

< SYSTEM DESCRIPTION >

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Monitored item

Unit

Description

Remarks

ENG SPEED

rpm

• Indicates the engine speed computed from the sig-

nal of the crankshaft position sensor (POS) and 
camshaft position sensor (PHASE).

• Accuracy becomes poor if engine speed 

drops below the idle rpm.

• If the signal is interrupted while the engine 

is running, an abnormal value may be in-
dicated.

MAS A/F SE-B1

V

• The signal voltage of the mass air flow sensor is 

displayed.

• When the engine is stopped, a certain val-

ue is indicated.

• When engine is running specification 

range is indicated in “SPEC”.

B/FUEL SCHDL

ms

• “Base fuel schedule” indicates the fuel injection 

pulse width programmed into ECM, prior to any 
learned on board correction.

• When engine is running specification 

range is indicated in “SPEC”.

A/F ALPHA-B1

%

• The mean value of the air-fuel ratio feedback cor-

rection factor per cycle is indicated.

• When the engine is stopped, a certain val-

ue is indicated.

• When engine is running specification 

range is indicated in “SPEC”.

• This data also includes the data for the 

air-fuel ratio learning control.

A/F ALPHA-B2

%

COOLANT TEMP/S

°C or °F

• The engine coolant temperature (determined by 

the signal voltage of the engine coolant tempera-
ture sensor) is displayed.

• When the engine coolant temperature 

sensor is open or short-circuited, ECM 
enters fail-safe mode. The engine coolant 
temperature determined by the ECM is 
displayed.

A/F SEN1 (B1)

V

• The A/F signal computed from the input signal of 

the Air fuel ratio (A/F) sensor 1 is displayed.

A/F SEN1 (B2)

V

HO2S2 (B1)

V

• The signal voltage of the heated oxygen sensor 2 

is displayed.

HO2S2 (B2)

V

HO2S2 MNTR(B1)

RICH/

LEAN

• Display of heated oxygen sensor 2 signal:

RICH: Means the amount of oxygen after three way 
catalyst is relatively small.
LEAN: Means the amount of oxygen after three 
way catalyst is relatively large.

• When the engine is stopped, a certain val-

ue is indicated.

HO2S2 MNTR(B2)

RICH/

LEAN

VHCL SPEED SE

km/h or 

mph

• The vehicle speed computed from the vehicle 

speed signal sent from combination meter is dis-
played.

BATTERY VOLT

V

• The power supply voltage of ECM is displayed.

ACCEL SEN 1

V

• The accelerator pedal position sensor signal volt-

age is displayed.

• ACCEL SEN 2 signal is converted by 

ECM internally. Thus, it differs from ECM 
terminal voltage signal.

ACCEL SEN 2

V

TP SEN 1-B1

V

• The throttle position sensor signal voltage is dis-

played.

• THRTL SEN 2 signal is converted by 

ECM internally. Thus, it differs from ECM 
terminal voltage signal.

TP SEN 2-B1

V

FUEL T/TMP SE

°C or °F

• The fuel temperature (determined by the signal 

voltage of the fuel tank temperature sensor) is dis-
played.

INT/A TEMP SE

°C or °F

• The intake air temperature (determined by the sig-

nal voltage of the intake air temperature sensor) is 
indicated.

EVAP SYS PRES

V

FUEL LEVEL SE

V

START SIGNAL

ON/OFF

• Indicates start signal status [ON/OFF] computed by 

the ECM according to the signals of engine speed 
and battery voltage.

• After starting the engine, [OFF] is dis-

played regardless of the starter signal.

EC-56

< SYSTEM DESCRIPTION >

[VQ40DE]

DIAGNOSIS SYSTEM (ECM)

CLSD THL POS

ON/OFF

• Indicates idle position [ON/OFF] computed by ECM 

according to the accelerator pedal position sensor 
signal.

AIR COND SIG

ON/OFF

• Indicates [ON/OFF] condition of the air conditioner 

switch as determined by the air conditioner signal.

P/N POSI SW

ON/OFF

• Indicates [ON/OFF] condition from the park/neutral 

position (PNP) signal.

PW/ST SIGNAL

ON/OFF

• [ON/OFF] condition of the power steering system 

(determined by the signal voltage of the power 
steering pressure sensor signal) is indicated.

LOAD SIGNAL

ON/OFF

• Indicates [ON/OFF] condition from the electrical 

load signal.
ON: Rear window defogger switch is ON and/or 
lighting switch is in 2nd position.
OFF: Both rear window defogger switch and light-
ing switch are OFF.

IGNITION SW

ON/OFF

• Indicates [ON/OFF] condition from ignition switch 

signal.

HEATER FAN SW

ON/OFF

• Indicates [ON/OFF] condition from the heater fan 

switch signal.

BRAKE SW

ON/OFF

• Indicates [ON/OFF] condition from the stop lamp 

switch signal.

INJ PULSE-B1

msec

• Indicates the actual fuel injection pulse width com-

pensated by ECM according to the input signals.

• When the engine is stopped, a certain 

computed value is indicated.

INJ PULSE-B2

msec

IGN TIMING

BTDC

• Indicates the ignition timing computed by ECM ac-

cording to the input signals.

• When the engine is stopped, a certain val-

ue is indicated.

CAL/LD VALUE

%

• Calculated load value indicates the value of the 

current air flow divided by peak air flow.

MASS AIRFLOW

g/s

• Indicates the mass air flow computed by ECM ac-

cording to the signal voltage of the mass air flow 
sensor.

PURG VOL C/V

%

• Indicates the EVAP canister purge volume control 

solenoid valve control value computed by the ECM 
according to the input signals.

• The opening becomes larger as the value increas-

es.

INT/V TIM(B1)

°CA

• Indicates [

°CA] of intake camshaft advanced angle. 

INT/V TIM(B2)

°CA

INT/V SOL(B1)

%

• The control condition of the intake valve timing con-

trol solenoid valve (determined by ECM according 
to the input signals) is indicated.

• The advance angle becomes larger as the value in-

creases.

INT/V SOL(B2)

%

SWRL CONT S/V

ON/OFF

• The control condition of the intake manifold runner 

control valve (determined by ECM according to the 
input signals) is indicated.

- ON: Closed
- OFF: Open

VIAS S/V-1

ON/OFF

• The control condition of the VIAS control solenoid 

valve (determined by ECM according to the input 
signals) is indicated.
ON: VIAS control solenoid valve is operating.
OFF: VIAS control solenoid valve is not operating.

AIR COND RLY

ON/OFF

• The air conditioner relay control condition (deter-

mined by ECM according to the input signals) is in-
dicated.

Monitored item

Unit

Description

Remarks

DIAGNOSIS SYSTEM (ECM)

EC-57

< SYSTEM DESCRIPTION >

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FUEL PUMP RLY

ON/OFF

• Indicates the fuel pump relay control condition de-

termined by ECM according to the input signals.

VENT CONT/V

ON/OFF

• The control condition of the EVAP canister vent 

control valve (determined by ECM according to the 
input signals) is indicated.
ON: Closed
OFF: Open

THRTL RELAY

ON/OFF

• Indicates the throttle control motor relay control 

condition determined by the ECM according to the 
input signals.

COOLING FAN

HI/LOW/

OFF

• The control condition of the cooling fan (deter-

mined by ECM according to the input signals) is in-
dicated.
HI: High speed operation
LOW: Low speed operation
OFF: Stop

HO2S2 HTR (B1)

ON/OFF • Indicates [ON/OFF] condition of heated oxygen 

sensor 2 heater determined by ECM according to 
the input signals.

HO2S2 HTR (B2)

ON/OFF

I/P PULLY SPD

rpm

• Indicates the engine speed computed from the in-

put speed sensor signal.

VEHICLE SPEED

km/h or 

mph

• Indicates the vehicle speed computed from the out-

put speed sensor signal.

IDL A/V LEARN

YET/

CMPLT

• Displays the condition of idle air volume learning

YET: Idle air volume learning has not been per-
formed yet.
CMPLT: Idle air volume learning has already been 
performed successfully.

TRVL AFTER MIL

km or 

mile

• Distance traveled while MIL is activated.

A/F S1 HTR(B1)

%

• Air fuel ratio (A/F) sensor 1 heater control value 

computed by ECM according to the input signals.

• The current flow to the heater becomes larger as 

the value increases.

A/F S1 HTR(B2)

%

AC PRESS SEN

V

• The signal voltage from the refrigerant pressure 

sensor is displayed.

VHCL SPEED SE

km/h or 

mph

• The vehicle speed computed from the vehicle 

speed signal sent from TCM is displayed.

SET VHCL SPD

km/h or 

mph

• The preset vehicle speed is displayed.

MAIN SW

ON/OFF

• Indicates [ON/OFF] condition from MAIN switch 

signal.

CANCEL SW

ON/OFF

• Indicates [ON/OFF] condition from CANCEL switch 

signal.

RESUME/ACC SW

ON/OFF

• Indicates [ON/OFF] condition from RESUME/AC-

CELERATE switch signal.

SET SW

ON/OFF

• Indicates [ON/OFF] condition from SET/COAST 

switch signal.

BRAKE SW1

ON/OFF

• Indicates [ON/OFF] condition from brake pedal po-

sition switch signal.

BRAKE SW2

ON/OFF

• Indicates [ON/OFF] condition of stop lamp switch 

signal.

Monitored item

Unit

Description

Remarks