2003 NISSAN TEANA width

DTC P0841 PRESSURE SENSOR FUNCTION
CVT-123
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CVT

DTC P0841 PRESSURE SENSOR FUNCTIONPFP:31936
DescriptionBCS001K3
Using the engine load (throttle position), the primary pulley revolution speed, and the secondary pulley revolu-
tion speed as input signal, TCM changes the operating pressure of the primary pulley and the secondary pul-
ley and changes the groove width of the pulley to control the gear ratio.
CONSULT-II Reference ValueBCS001K4
Remarks: Specification data are reference values.
On Board Diagnosis LogicBCS001K5
Diagnostic trouble code “P0841 PRESS SEN/FNCTN” with CONSULT-II is detected when correlation between
the values of the secondary pressure sensor and the primary pressure sensor is out of specification.
Possible CauseBCS001K6

Transmission fluid pressure sensor A (Secondary pressure sensor)

Transmission fluid pressure sensor B (Primary pressure sensor)

Harness or connectors
(Sensor circuit is open or shorted.)
DTC Confirmation ProcedureBCS001K7
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch OFF and
wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Turn ignition switch ON and select “DATA MONITOR” mode for
“TRANSMISSION” with CONSULT-II.
2. Start engine and maintain the following conditions for at least 12
consecutive seconds.
VEHICLE SPEED: 40 km/h (25 MPH) More than
RANGE: “D” position
3. If DTC is detected, go to CVT-124, "
Diagnostic Procedure" .
Item name Condition Display value (Approx.)
PRI HYDR SEN
“N” position idle0.7 - 3.5 V
SEC HYDR SEN1.0 V
BCIA0031E

DTC P1777 STEP MOTOR - CIRCUIT
CVT-155
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CVT

TCM terminals data are reference values.
Diagnostic ProcedureBCS001LY
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “TRANSMISSION” with CONSULT-II.
3. Start vehicle and read out the value of “STM STEP”, “SMCOIL
A”, “SMCOIL B”, “SMCOIL C”, and “SMCOIL D”.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2. CHECK HARNESS BETWEEN TCM AND STEP MOTOR
1. Turn ignition switch OFF.
2. Disconnect CVT unit connector and TCM connector.
3. Check continuity between TCM connector terminals and CVT
unit harness connector terminals.
4. If OK, check harness for short to ground and short to power.
5. If OK, check continuity between body ground and CVT assembly.
6. Reinstall any part removed.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
Terminal Wire color Item Condition Data (Approx.)
11 G/R Step motor A Within 2 seconds after ignition switch ON, the time measure-
ment by using the pulse width measurement function (Hi level) of
CONSULT-II.*1
CAUTION:
Connect the diagnosis data link cable to the vehicle diagno-
sis connector.
*1: A circuit tester cannot be used to test this item.30.0 msec
12 O/B Step motor B10.0 msec
20 R Step motor C30.0 msec
21 R/G Step motor D10.0 msec
Item name Condition Display value (Approx.)
STM STEP
During driving−20 step - 190 step
SMCOIL A
Changes ON⇔OFF SMCOIL B
SMCOIL C
SMCOIL D
SCIA4516E
Item Connector Terminal Continuity
TCM F106 11
Ye s
CVT unit harness connector F49 6
TCM F106 12
Ye s
CVT unit harness connector F49 7
TCM F106 20
Ye s
CVT unit harness connector F49 8
TCM F106 21
Ye s
CVT unit harness connector F49 9
SCIA4695E

EC-22
[QR]
ENGINE CONTROL SYSTEM

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better reduce CO, HC and NOx emissions. This system uses
heated oxygen sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about
heated oxygen sensor 1, refer to EC-143
. This maintains the mixture ratio within the range of stoichiometric
(ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching
characteristics of heated oxygen sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal
from heated oxygen sensor 2.
Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.

Deceleration and acceleration

High-load, high-speed operation

Malfunction of heated oxygen sensor 1 or its circuit

Insufficient activation of heated oxygen sensor 1 at low engine coolant temperature

High engine coolant temperature

During warm-up

After shifting from N to D

When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from heated oxygen
sensor 1. This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to
the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as orig-
inally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic
changes during operation (i.e., fuel injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN compared
to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an
increase in fuel volume if it is lean.
“Long term fuel trim” is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
PBIB2953E

ENGINE CONTROL SYSTEM
EC-23
[QR]
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EC

FUEL INJECTION TIMING
Two types of systems are used.
Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all four cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The four fuel injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
Electronic Ignition (EI) SystemBBS005BG
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Firing order: 1-3-4-2
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Comput-
ing this information, ignition signals are transmitted to the power transistor.
During the following conditions, the ignition timing is revised by the ECM according to the other data stored in
the ECM.

At starting

During warm-up

At idle

At low battery voltage

During acceleration
SEF337W
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
controlPower transistor Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor
Vehicle speed*1

TROUBLE DIAGNOSIS
EC-83
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DATA MONITOR MODE
Monitored Item
×: Applicable
Monitored item [Unit]ECM
INPUT
SIG-
NALSMAIN
SIG-
NALSDescription Remarks
ENG SPEED [rpm]××

Indicates the engine speed computed from
the signals of the crankshaft position sen-
sor (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 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 cer-
tain value is indicated.
B/FUEL SCHDL
[msec]×

“Base fuel schedule” indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board correc-
tion.
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 cer-
tain value is indicated.

This data also includes the data for
the air-fuel ratio learning control.
COOLAN 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 tempera-
ture sensor is open or short-circuited,
ECM enters fail-safe mode. The
engine coolant temperature deter-
mined by the ECM is displayed.
HO2S1 (B1) [V]××

The signal voltage of the heated oxygen
sensor 1 is displayed.
HO2S2 (B1) [V]×

The signal voltage of the heated oxygen
sensor 2 is displayed.
HO2S1 MNTR (B1)
[RICH/LEAN]××

Display of heated oxygen sensor 1 signal
during air-fuel ratio feedback control:
RICH: means the mixture became “rich”,
and control is being affected toward a
leaner mixture.
LEAN: means the mixture became “lean”,
and control is being affected toward a rich
mixture.
After turning ON the ignition switch,
“RICH” is displayed until air-fuel mix-
ture ratio feedback control begins.

When the air-fuel ratio feedback is
clamped, the value just before the
clamping is displayed continuously.
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 cer-
tain 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 sig-
nal voltage is displayed.
ACCEL SEN 2 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal. ACCEL SEN 2 [V]×
THRTL SEN 1 [V]××

The throttle position sensor signal voltage
is displayed.
THRTL SEN 2 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal. THRTL SEN 2 [V]×

EC-84
[QR]
TROUBLE DIAGNOSIS

INT/A TEMP SE
[°C] or [°F]××
The intake air temperature (determined by
the signal voltage of the intake air tempera-
ture sensor) is indicated.
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 dis-
played regardless of the starter sig-
nal.
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
conditioner signal.
P/N POSI SW
[ON/OFF]××

Indicates [ON/OFF] condition from the park/
neutral position (PNP) switch signal.
PW/ST SIGNAL
[ON/OFF]××

[ON/OFF] condition of the power steering
system (determined by the power steering
pressure sensor signal) is indicated.
LOAD SIGNAL
[ON/OFF]××

Indicates [ON/OFF] condition from the elec-
trical 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.
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 compensated by ECM according to
the input signals.
When the engine is stopped, a cer-
tain computed value is indicated.
IGN TIMING [BTDC]×

Indicates the ignition timing computed by
ECM according to the input signals.
When the engine is stopped, a cer-
tain value is indicated.
PURG VOL C/V [%]

Indicates the EVAP canister purge volume
control solenoid valve control value com-
puted by the ECM according to the input
signals.

The opening becomes larger as the value
increases.
INT/V TIM (B1) [°CA]

Indicates [°CA] of intake camshaft
advanced angle.
INT/V SOL (B1) [%]

The control value of the intake valve timing
control solenoid valve (determined by ECM
according to the input signal) is indicated.

The advance angle becomes larger as the
value increases
AIR COND RLY
[ON/OFF]×

The air conditioner relay control condition
(determined by ECM according to the input
signals) is indicated. Monitored item [Unit]ECM
INPUT
SIG-
NALSMAIN
SIG-
NALSDescription Remarks

TROUBLE DIAGNOSIS
EC-85
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EC

NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.FUEL PUMP RLY
[ON/OFF]×

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

The control condition of the cooling fan
(determined by ECM according to the input
signals) is indicated.
HI... High speed operation
MID... Middle speed operation
LOW... Low speed operation
OFF... Stop
HO2S1 HTR (B1)
[ON/OFF]

Indicates [ON/OFF] condition of heated
oxygen sensor 1 heater determined by
ECM according to the input signals.
HO2S2 HTR (B1)
[ON/OFF]

Indicates [ON/OFF] condition of heated
oxygen sensor 2 heater determined by
ECM according to the input signals.
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
already been performed successfully.
O2SEN HTR DTY
[%]

Indicates the heated oxygen sensor 1
heater control value computed by the ECM
according to the input signals.
AC PRESS SEN [V]

The signal voltage from the refrigerant
pressure sensor is displayed.
Voltage [V]

Voltage, frequency, duty cycle or pulse
width measured by the probe.

Only “#” is displayed if item is unable
to be measured.

Figures with “#”s are temporary ones.
They are the same figures as an
actual piece of data which was just
previously measured. Frequency
[msec], [Hz] or [%]
DUTY-HI
DUTY-LOW
PLS WIDTH-HI
PLS WIDTH-LOWMonitored item [Unit]ECM
INPUT
SIG-
NALSMAIN
SIG-
NALSDescription Remarks

EC-86
[QR]
TROUBLE DIAGNOSIS

DATA MONITOR (SPEC) MODE
Monitored Item
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ACTIVE TEST MODE
Test Item
Monitored item [Unit]ECM
INPUT
SIGNALSMAIN
SIGNALSDescription Remarks
ENG SPEED [rpm]×

Indicates the engine speed computed
from the signals of the crankshaft posi-
tion sensor (POS) and camshaft position
sensor (PHASE).
MAS A/F SE-B1 [V]××

The signal voltage of the mass air flow
sensor specification is displayed.
When engine is running specification
range is indicated.
B/FUEL SCHDL
[msec]

“Base fuel schedule” indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board cor-
rection.

When engine is running specification
range is indicated.
A/F ALPHA-B1 [%]×

The mean value of the air-fuel ratio feed-
back correction factor per cycle is indi-
cated.
When engine is running specification
range is indicated.

This data also includes the data for the
air-fuel ratio learning control.
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJEC-
TION

Engine: Return to the original
trouble condition

Change the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Harness and connectors

Fuel injector

Heated oxygen sensor 1
IGNITION TIM-
ING

Engine: Return to the original
trouble condition

Timing light: Set

Retard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Perform Idle Air Volume Learning.
POWER BAL-
ANCE

Engine: After warming up, idle
the engine.

Air conditioner switch OFF

Shift lever: P or N

Cut off each fuel injector signal
one at a time using CONSULT-II.Engine runs rough or dies.

Harness and connectors

Compression

Fuel injector

Power transistor

Spark plug

Ignition coil
COOLING FAN*

Ignition switch: ON

Turn the cooling fan LOW, MID,
HI, OFF with CONSULT-II.Cooling fan moves and stops.

Harness and connectors

Cooling fan motor

IPDM E/R
ENG COOLANT
TEMP

Engine: Return to the original
trouble condition

Change the engine coolant tem-
perature using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.

Harness and connectors

Engine coolant temperature sen-
sor

Fuel injector
FUEL PUMP
RELAY

Ignition switch: ON (Engine
stopped)

Turn the fuel pump relay ON and
OFF using CONSULT-II and lis-
ten to operating sound.Fuel pump relay makes the operat-
ing sound.
Harness and connectors

Fuel pump relay