Nissan Sentra. Manual - part 343

EC-68

< SYSTEM DESCRIPTION >

[MRA8DE]

DIAGNOSIS SYSTEM (ECM)

×: Applicable

Monitored item

Unit

Monitor Item Selection

Description

Remarks

ECU INPUT 

SIGNALS

MAIN 

SIGNALS

ENG SPEED

rpm

×

×

Indicates the engine speed computed from 
the signal 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 run-
ning, an abnormal value 
may be indicated.

MAS A/F SE-B1

V

×

×

The signal voltage of the mass air flow sen-
sor is displayed.

• When the engine is 

stopped, a certain value 
is indicated.

• When engine is running 

specification range is in-
dicated in “SPEC”.

B/FUEL SCHDL

msec

×

×

“Base fuel schedule” indicates the fuel injec-
tion pulse width programmed into ECM, pri-
or to any learned on board correction.

When engine is running 
specification range is indi-
cated in “SPEC”.

A/F ALPHA-B1

%

The mean value of the air-fuel ratio feed-
back correction factor per cycle is indicated.

• When the engine is 

stopped, a certain value 
is indicated.

• When engine is running 

specification range is in-
dicated in “SPEC”.

• This data also includes 

the data for the air-fuel 
ratio learning control.

COOLANT 
TEMP/S

°C or °F

×

×

The engine coolant temperature (deter-
mined by the signal voltage of the engine 
coolant temperature sensor) is displayed.

When the engine coolant 
temperature sensor circuit 
is open or shorted, ECM 
enters fail-safe mode. The 
engine coolant tempera-
ture determined by the 
ECM is displayed.

A/F SEN1 (B1)

V

×

×

The A/F signal computed from the input sig-
nal of the air fuel ratio (A/F) sensor 1 is dis-
played.

HO2S2 (B1)

V

×

×

The signal voltage of the heated oxygen 
sensor 2 is displayed.

HO2S2 MNTR 
(B1)

LEAN/RICH

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 value is 
indicated.

VHCL SPEED 
SE

km/h or mph

×

×

The vehicle speed computed from the vehi-
cle speed signal sent from combination 
meter is displayed.

BATTERY VOLT

V

The power supply voltage of ECM is dis-
played.

ACCEL SEN 1

V

The accelerator pedal position sensor signal 
voltage is displayed.

ACCEL SEN 2 signal is 
converted by ECM internal-
ly. Thus, it differs from ECM 
terminal voltage signal.

ACCEL SEN 2

TP SEN 1-B1

V

×

×

The throttle position sensor signal voltage is 
displayed.

TP SEN 2-B1 signal is con-
verted by ECM internally. 
Thus, it differs from ECM 
terminal voltage signal.

TP SEN 2-B1

×

×

DIAGNOSIS SYSTEM (ECM)

EC-69

< SYSTEM DESCRIPTION >

[MRA8DE]

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FUEL T/TMP SE

°C or °F

• The fuel temperature (determined by the 

signal voltage of the fuel tank temperature 
sensor) is displayed.

EVAP SYS 
PRES

V

• The signal voltage of EVAP control sys-

tem pressure sensor is displayed.

FUEL LEVEL SE

V

×

• The signal voltage of the fuel level sensor 

is displayed.

START SIGNAL

ON/OFF

Indicates start signal status [ON/OFF] com-
puted by the ECM according to the signals 
of engine speed and battery voltage.

After starting the engine, 
[OFF] is displayed regard-
less of the starter signal.

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 con-
ditioner switch as determined by the air con-
ditioner signal.

PW/ST SIGNAL

ON/OFF

×

×

Indicates [ON/OFF] condition of the power 
steering system (determined by the signal 
sent from EPS control unit) 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 lighting 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 heat-
er 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 compensated by ECM according to 
the input signals.

IGN TIMING

BTDC

×

Indicates the ignition timing computed by 
ECM according to the input signals.

When the engine is 
stopped, a certain value is 
indicated.

CAL/LD VALUE

%

“Calculated load value” indicates the value 
of the current airflow divided by peak airflow.

MASS AIR 
FLOW

g/s

Indicates the mass airflow computed by 
ECM according to the signal voltage of the 
mass airflow sensor.

PURG VOL C/V

%

• Indicates the EVAP canister purge vol-

ume control solenoid valve control value 
computed by the ECM according to the in-
put signals.

• The opening becomes larger as the value 

increases.

INT/V TIM (B1)

°CA

Indicates [

°CA] of intake camshaft advance 

angle. 

EXH/V TIM B1

°CA

Indicates [

°CA] of exhaust camshaft ad-

vance angle. 

Monitored item

Unit

Monitor Item Selection

Description

Remarks

ECU INPUT 

SIGNALS

MAIN 

SIGNALS

EC-70

< SYSTEM DESCRIPTION >

[MRA8DE]

DIAGNOSIS SYSTEM (ECM)

INT/V SOL (B1)

%

• The control value of the intake valve tim-

ing control solenoid valve (determined by 
ECM according to the input signals) is in-
dicated.

• The advance angle becomes larger as the 

value increases.

SWRL CONT S/
V

On/Off

• The control condition of the intake mani-

fold runner control valve (determined by 
ECM according to the input signals) is in-
dicated.

- On: Closed
- Off:  Open

VIAS S/V-1

On/Off

AIR COND RLY

ON/OFF

The air conditioner relay control condition 
(determined by ECM according to the input 
signals) is indicated.

FUEL PUMP 
RLY

ON/OFF

Indicates the fuel pump relay control condi-
tion determined by ECM according to the in-
put signals.

VENT CONT/V

On/Off

• The control condition of the EVAP canis-

ter vent control valve (determined by ECM 
according to the input signals) is indicat-
ed.

- 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/Mid/Low/

Off

Indicates the condition of the cooling fan 
(determined by ECM according to the input 
signals).
• HI: High speed operation
• MID: Middle speed operation
• LOW: Low speed operation
• Off:  Stop

HO2S2 HTR 
(B1)

ON/OFF

Indicates [ON/OFF] condition of heated oxy-
gen sensor 2 heater determined by ECM ac-
cording to the input signals.

ALT DUTY SIG

ON/OFF

• The control condition of the power gener-

ation voltage variable control (determined 
by ECM according to the input signals) is 
indicated.

- ON: Power generation voltage variable 

control is active.

- OFF: Power generation

I/P PULLY SPD

rpm

Indicates the engine speed computed from 
the input speed sensor signal.

VEHICLE 
SPEED

km/h or mph

The vehicle speed computed from the vehi-
cle speed signal sent from TCM is dis-
played.

IDL A/V LEARN

YET/CMPLT

• Display the condition of Idle Air Volume 

Learning

- YET: Idle air volume learning has not 

been performed yet.

- CMPLT: Idle air volume learning has al-

ready been performed successfully.

Monitored item

Unit

Monitor Item Selection

Description

Remarks

ECU INPUT 

SIGNALS

MAIN 

SIGNALS

DIAGNOSIS SYSTEM (ECM)

EC-71

< SYSTEM DESCRIPTION >

[MRA8DE]

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TRVL AFTER 
MIL

km/h or mph

Distance traveled while MIL is activated.

ENG OIL TEMP

°C or °F

The engine oil temperature (determined by 
the signal voltage of the engine oil tempera-
ture sensor) is displayed.

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.

VHCL SPEED 
SE

km/h or mph

The vehicle speed computed from the vehi-
cle speed signal sent from combination 
meter 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 RE-
SUME/ACCELERATE switch signal.

SET SW

On/Off

Indicates [ON/OFF] condition from SET/
COAST switch signal.

BRAKE SW 1

On/Off

Indicates [ON/OFF] condition from ASCD 
brake switch signal.

BRAKE SW 2

On/Off

Indicates [ON/OFF] condition from stop 
lamp switch signal.

VHCL SPD CUT

Non/Cut

Indicates the vehicle cruise condition.
• Non: Vehicle speed is maintained at the 

ASCD set speed.

• Cut: Vehicle speed decreased to exces-

sively low compared with ASCD set 
speed, and ASCD operation is cut off.

LO SPEED CUT

Non/Cut

Indicates the vehicle cruise condition.
• Non: Vehicle speed is maintained at the 

ASCD set speed.

• Cut: Vehicle speed decreased to exces-

sively low, and ASCD operation is cut off.

AT OD MONI-
TOR

On/Off

Indicates [ON/OFF] condition of A/T O/D ac-
cording to the input signal from the TCM.

AT OD CANCEL

On/Off

Indicates [ON/OFF] condition of A/T O/D 
cancel request signal.

CRUISE LAMP

On/Off

Indicates [ON/OFF] condition of CRUISE 
lamp determined by the ECM according to 
the input signals.

SET LAMP

On/Off

Indicates [ON/OFF] condition of SET lamp 
determined by the ECM according to the in-
put signals.

ALT DUTY

%

Indicates the duty ratio of the power genera-
tion command value. The ratio is calculated 
by ECM based on the battery current sensor 
signal.

BAT CUR SEN

mV

The signal voltage of battery current sensor 
is displayed.

Monitored item

Unit

Monitor Item Selection

Description

Remarks

ECU INPUT 

SIGNALS

MAIN 

SIGNALS