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]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

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]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

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