2003 NISSAN TEANA throttle

A/T CONTROL SYSTEM
AT-29
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AT LOW FLUID TEMPERATURE

A/T fluid viscosity and frictional characteristics of the clutch facing change with A/T fluid temperature.
Clutch engaging or band-contacting pressure is compensated for, according to A/T fluid temperature, to
stabilize shifting quality.

The line pressure is reduced below 60°C (140°F) to prevent
shifting shock due to low viscosity of A/T fluid when temperature
is low.

Line pressure is increased to a maximum irrespective of the
throttle opening when A/T fluid temperature drops to −10°C
(14°F). This pressure rise is adopted to prevent a delay in clutch
and brake operation due to extreme drop of A/T fluid viscosity at
low temperature.
Shift ControlBCS000ZT
The shift is regulated entirely by electronic control to accommodate vehicle speed and varying engine opera-
tions. This is accomplished by electrical signals transmitted by the revolution sensor and the ECM (accelerator
pedal position sensor). This results in improved acceleration performance and fuel economy.
CONTROL OF SHIFT SOLENOID VALVES A AND B
The TCM activates shift solenoid valves A and B according to sig-
nals from the accelerator pedal position sensor and revolution sen-
sor to select the optimum gear position on the basis of the shift
schedule memorized in the TCM.
The shift solenoid valve performs simple ON-OFF operation. When
set to “ON”, the drain circuit closes and pilot pressure is applied to
the shift valve.
RELATION BETWEEN SHIFT SOLENOID VALVES A AND B AND GEAR POSITIONS
SCIA4829E
SCIA4830E
SAT008J
Gear position 1 2 3 4
Shift solenoid valve A ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Shift solenoid valve B ON (Closed) ON (Closed) OFF (Open) OFF (Open)

AT-30
A/T CONTROL SYSTEM

CONTROL OF SHIFT VALVES A AND B
Pilot pressure generated by the operation of shift solenoid valves A and B is applied to the end face of shift
valves A and B.
The figure above shows the operation of shift valve B. When the shift solenoid valve is “ON”, pilot pressure
applied to the end face of the shift valve overcomes spring force, moving the valve upward.
Lock-up ControlBCS000ZU
The torque converter clutch piston in the torque converter is locked to eliminate torque converter slip to
increase power transmission efficiency. The solenoid valve is controlled by an ON-OFF duty signal sent from
the TCM. The signal is converted to an oil pressure signal which controls the torque converter clutch piston.
CONDITIONS FOR LOCK-UP OPERATION
When vehicle is driven in 3rd and 4th gear position, vehicle speed and throttle opening are detected. If the
detected values fall within the lock-up zone memorized in the TCM, lock-up is performed.
TORQUE CONVERTER CLUTCH SOLENOID VALVE CONTROL
Lock-up Control System Diagram
SAT009J
Selector lever “D” position “3” position
Gear position D
4 , D333
Vehicle speed sensor More than set value
accelerator pedal position sensor Less than set opening
Closed throttle position signal OFF
A/T fluid temperature sensor More than 20°C (68°F)
SCIA5623E

A/T CONTROL SYSTEM
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Lock-up Released
In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by drain-
ing the torque converter clutch piston applying pressure and the torque converter clutch piston release pres-
sure is generated.
In this way, the torque converter clutch piston is not coupled.
Lock-up Applied
In the lock-up applied state, the torque converter clutch control valve is set into the locked state by generating
the torque converter clutch piston applying pressure and the torque converter clutch piston release pressure is
drained.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.
Half-clutched State
The current output from the TCM to the torque converter clutch solenoid is varied to steadily increase the
torque converter clutch solenoid pressure.
In this way, the lock-up applying pressure gradually rises and while the torque converter clutch piston is put
into half-clutched status, the torque converter clutch piston applying pressure is increased and the coupling is
completed smoothly.
Engine Brake Control (Overrun Clutch Control)BCS000ZV
Forward one-way clutch is used to reduce shifting shocks in downshifting operations. This clutch transmits
engine torque to the wheels. However, drive force from the wheels is not transmitted to the engine because
the one-way clutch rotates idle. This means the engine brake is not effective.
The overrun clutch operates when the engine brake is needed.
OVERRUN CLUTCH OPERATING CONDITIONS
SCIA4831E
Selector lever position Gear position Throttle opening
“D” position D
1 , D2 , D3 gear position
Less than 3/16
“3” position 3
1 , 32 , 33 gear position
“2” position 2
1 , 22 gear position
At any position
“1” position 1
1 , 12 gear position

A/T CONTROL SYSTEM
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Control ValveBCS000ZW
FUNCTION OF CONTROL VALVES
Valve name Function
Pressure regulator valve, plug and sleeve
plugRegulates oil discharged from the oil pump to provide optimum line pressure for all driv-
ing conditions.
Pressure modifier valve and sleeve Used as a signal supplementary valve to the pressure regulator valve. Regulates pres-
sure-modifier pressure (signal pressure) which controls optimum line pressure for all
driving conditions.
Pilot valve Regulates line pressure to maintain a constant pilot pressure level which controls lock-up
mechanism, overrun clutch, shift timing.
Accumulator control valve Regulates accumulator back-pressure to pressure suited to driving conditions.
Manual valve Directs line pressure to oil circuits corresponding to select positions.
Hydraulic pressure drains when the shift lever is in Neutral.
Shift valve A Simultaneously switches three oil circuits using output pressure of shift solenoid valve A
to meet driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and upshifting (1st → 2nd → 3rd → 4th gears/4th →
3rd → 2nd → 1st gears) in combination with shift valve B.
Shift valve B Simultaneously switches two oil circuits using output pressure of shift solenoid valve B in
relation to driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and upshifting (1st → 2nd → 3rd → 4th gears/4th →
3rd → 2nd → 1st gears) in combination with shift valve A.
Overrun clutch control valve Switches hydraulic circuits to prevent engagement of the overrun clutch simultaneously
with application of the brake band in D
4 . (Interlocking occurs if the overrun clutch
engages during D
4 .)
1st reducing valve Reduces low & reverse brake pressure to dampen engine-brake shock when downshift-
ing from the 1st position 1
2 to 11 .
Overrun clutch reducing valve Reduces oil pressure directed to the overrun clutch and prevents engine-brake shock.
In the 1st and 2nd positions, line pressure acts on the overrun clutch reducing valve to
increase the pressure-regulating point, with resultant engine brake capability.
Torque converter relief valve Prevents an excessive rise in torque converter pressure.
Torque converter clutch control valve, plug
and sleeveActivates or inactivates the lock-up function.
Also provides smooth lock-up through transient application and release of the lock-up
system.
1-2 accumulator valve and piston Lessens the shock find when the 2nd gear band servo contracts, and provides smooth
shifting.
3-2 timing valve Switches the pace that oil pressure is released depending on vehicle speed; maximizes
the high clutch release timing, and allows for soft downshifting.
Shuttle valve Determines if the overrun clutch solenoid valve should control the 3-2 timing valve or the
overrun clutch control valve and switches between the two.
Cooler check valve At low speeds and with a small load when a little heat is generated, saves the volume of
cooler flow, and stores the oil pressure for lock-up.

AT-34
TROUBLE DIAGNOSIS

TROUBLE DIAGNOSISPFP:00004
DTC Inspection Priority ChartBCS000ZX
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC “CAN COMM CIRCUIT” is displayed with other DTCs, first perform the trouble diagnosis for
“CAN COMMUNICATION LINE”. Refer to AT- 1 3 3
.
Fail-safeBCS000ZY
The TCM has an electronic Fail-safe mode. This allows the vehicle to be driven even if a major electrical input/
output device circuit is damaged.
Under Fail-safe, the vehicle always runs in third gear, even with a shift lever position of “1”, “2”, “3” or “D”. The
customer may complain of sluggish or poor acceleration.
Always follow the AT- 3 7 , "
WORK FLOW" .
The SELF-DIAGNOSIS results will be as follows:

The first SELF-DIAGNOSIS will indicate damage to the vehicle speed sensor or the revolution sensor.

During the next SELF-DIAGNOSIS, performed after checking the sensor, no damages will be indicated.
FAIL-SAFE FUNCTION
The following fail-safe functions allow vehicles to be driven even when sensor, switch or solenoid malfunction
occurs.
Vehicle Speed Sensor 1 (Revolution Sensor)
Vehicle speed sensor 2 signal is input from combination meter.
Accelerator Pedal Position Sensor Signal
TCM controls the throttle opening angle to a predetermined fixed position to enable driving if a malfunctioning
signal is input to TCM.
Park/Neutral Position (PNP) Switch
When the multiple PNP switch signals are input to TCM, the priority of selector lever position becomes “D”·“3”,
“N”, “R”, “2” and “1” in order by internal TCM determination.
The use of 4th gear is inhibited until normal operation resumes. Because the hydraulic circuit of the control
valve is switched by manual valve according to the selector lever position, however, actual operating condition
of vehicle becomes as follows.
Priority Detected items
1 CAN communication line
2 Except above
Actual lever position PNP switch input signal Running status
“P” “P” position and other position signals P
“R” “R” position and other position signals R
“N” “N” position and other position signals N
“D”·“3” “D” position and other position signals D
1 ⇔D2 ⇔D3
“2”“2” position and other position signals (Except “1” position) 21 ⇔22 ⇔23
“2” position and “1” position signals 21 ⇔22
“1”“1” position and other position signals (Except “2” position) 11 ⇔12 ⇔13
“1” position and “2” position signals 11 ⇔12

AT-44
TROUBLE DIAGNOSIS

6. Accelerate to wide open throttle gradually while applying foot
brake.
7. Quickly note the engine stall revolution and immediately release
throttle.
CAUTION:
Do not hold down the accelerator pedal for more than 5 sec-
onds during this test.
8. Move selector lever to “N” position.
9. Cool off ATF.
CAUTION:
Run engine at idle for at leas 1 minute.
10. Repeat steps 6 through 9 with selector lever in “3”, “2”, “1” and
“R” positions.
Judgement of Stall Test
The test result and possible damaged components relating to each result are shown in the illustrations on next
page.
In order to pinpoint the possible damaged components, refer to AT- 3 7 , "
Work Flow Chart" .
NOTE:
Stall revolution is too high in “D”, “3”, “2”, or “1” position:

Slippage occurs in 1st gear but not in 2nd and 3rd gears. ..... Low one-way clutch slippage

Slippage occurs in the following gears:
1st through 3rd gears in “D” position and engine brake functions with selector lever set to “3” position.
1st and 2nd gears in “2” position and engine brake functions with accelerator pedal released (fully closed
throttle)...... Forward clutch or forward one-way clutch slippage
Stall revolution is too high in “R” position:

Engine brake does not function in “1” position. ..... Low & reverse brake slippage

Engine brake functions in “1” position. ..... Reverse clutch slippage
Stall revolution within specifications:

Vehicle does not achieve speed of more than 80 km/h (50 MPH). ..... One-way clutch seizure in torque
converter housing
CAUTION:
Be careful since automatic fluid temperature increases abnormally.

Slippage occurs in 3rd and 4th gears in “D” position. ..... High clutch slippage

Slippage occurs in 2nd and 4th gear in “D” position. ..... Brake band slippage

Engine brake does not function in 2nd and 3rd gears in “D” position with 3rd position switch set to ON, 2nd
gear in “2” position, and 1st gear in “1” position. ..... Overrun clutch slippage
Stall revolution less than specifications:

Poor acceleration during starts. ..... One-way clutch seizure in torque converterStall revolution
For QR20DE engine models:
2,400 - 2,850 rpm
For VQ23DE engine models:
2,400 - 2,900 rpm
SAT514G
SCIA5704E

AT-50
TROUBLE DIAGNOSIS

Cruise Test — Part 1BCS00106
1. CHECK STARTING GEAR (D1 ) POSITION
1. Drive vehicle for approximately 10 minutes to warm engine oil and ATF up to operating temperature.
2. Park vehicle on flat surface.
3. Move selector lever to “P” position.
4. Start engine.
5. Move selector lever to “D” position.
6. Accelerate vehicle by constantly depressing accelerator pedal half-way.
Read gear position. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does vehicle start from D
1 ?
YES >> GO TO 2.
NO >>

Mark the box AT- 1 8 2 , "Vehicle Cannot Be Started From D1" on the AT- 3 8 , "DIAGNOSTIC
WORKSHEET" .

Continue “Road Test”.
2. CHECK SHIFT-UP (D1 TO D2 )
Check shift-up (D
1 to D2 ).
Specified speed when shifting from D
1 to D2 (Throttle position: half throttle). Refer to AT- 5 4 , "Vehicle Speed
Which Gear Shifting Occurs" .
Read gear position, throttle opening and vehicle speed. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does A/T shift from D
1 to D2 at the specified speed?
YES >> GO TO 3.
NO >>

Mark the box AT- 1 8 4 , "A/T Does Not Shift: D1 → D2 or Does Not Kickdown: D4 → D2" on the
AT- 3 8 , "
DIAGNOSTIC WORKSHEET" .

Continue “Road Test”.
3. CHECK SHIFT-UP (D2 TO D3 )
Check shift-up (D
2 to D3 ).
Specified speed when shifting from D
2 to D3 (Throttle position: half throttle). Refer to AT- 5 4 , "Vehicle Speed
Which Gear Shifting Occurs" .
Read gear position, throttle opening and vehicle speed. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does A/T shift from D
2 to D3 at the specified speed?
YES >> GO TO 4.
NO >>

Mark the box AT- 1 8 6 , "A/T Does Not Shift: D2 → D3" on the AT- 3 8 , "DIAGNOSTIC WORK-
SHEET" .

Continue “Road Test”.
4. CHECK SHIFT-UP (D3 TO D4 )
Check shift-up (D
3 to D4 ).
Specified speed when shifting from D
3 to D4 (Throttle position: half throttle). Refer to AT- 5 4 , "Vehicle Speed
Which Gear Shifting Occurs" .
Read gear position, throttle opening and vehicle speed. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does A/T shift from D
3 to D4 at the specified speed?
YES >> GO TO 5.
NO >>

Mark the box AT- 1 8 8 , "A/T Does Not Shift: D3 → D4" on the AT- 3 8 , "DIAGNOSTIC WORK-
SHEET" .

Continue “Road Test”. ATF operating temperature: 50 - 80°C (122 - 176°F)

TROUBLE DIAGNOSIS
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5. CHECK LOCK-UP (D4 TO D4 L/U)
Check lock-up (D
4 to D4 L/U).
Specified speed when lock-up occurs (Throttle position: half throttle). Refer to AT- 5 4 , "
Vehicle Speed at When
Lock-up Occurs/Releases" .
Read vehicle speed, throttle opening when lock-up duty becomes 94%. Refer to AT- 7 0 , "
DATA
MONITOR MODE" .
Does A/T perform lock-up at specified speed?
YES >> GO TO 6.
NO >>

Mark the box AT- 1 9 1 , "A/T Does Not Perform Lock-up" on the AT- 3 8 , "DIAGNOSTIC WORK-
SHEET" .

Continue “Road Test”.
6. CHECK LOCK-UP HOLD
Check lock-up hold.
When lock-up duty becomes 94%. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does A/T hold lock-up condition for more than 30 seconds?
YES >> GO TO 7.
NO >>

Mark the box AT- 1 9 3 , "A/T Does Not Hold Lock-up Condition" on the AT- 3 8 , "DIAGNOSTIC
WORKSHEET" .

Continue “Road Test”.
7. CHECK SHIFT-DOWN (D4 L/U TO D4 )
Release accelerator pedal.
When lock-up duty becomes 4%. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Is lock-up released when accelerator pedal is released?
YES >> GO TO 8.
NO >>

Mark the box AT- 1 9 5 , "Lock-up Is Not Released" on the AT- 3 8 , "DIAGNOSTIC WORKSHEET"
.

Continue “Road Test”.
8. CHECK SHIFT-DOWN (D4 TO D3 )
Decelerate vehicle by applying foot brake lightly.
Read gear position and engine speed. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does engine speed return to idle smoothly when A/T is shifted from D
4 to D3 ?
YES >> 1. Stop vehicle.
2. Go to AT- 5 1 , "
Cruise Test — Part 2" .
NO >>

Mark the box AT- 1 9 5 , "Engine Speed Does Not Return To Idle (Light Braking D4 → D3 )" on the
AT- 3 8 , "
DIAGNOSTIC WORKSHEET" .

Continue “Road Test”.
Cruise Test — Part 2BCS00107
1. CHECK STARTING GEAR (D1 ) POSITION
1. Move selector lever to “D” position.
2. Accelerate vehicle by half throttle again.
Read gear position. Refer to AT- 7 0 , "
DATA MONITOR MODE" .
Does vehicle start from D
1 ?
YES >> GO TO 2.
NO >>

Mark the box AT- 1 8 2 , "Vehicle Cannot Be Started From D1" on the AT- 3 8 , "DIAGNOSTIC
WORKSHEET" .

Continue “Road Test”.