2008 NISSAN LATIO oil

AT-34
< SERVICE INFORMATION >
A/T CONTROL SYSTEM
Control Valve
INFOID:0000000001703170
FUNCTION OF CONTROL VALVES
Centrifugal Cancel MechanismINFOID:0000000001703171
FUNCTION
The centrifugal cancel mechanism is a mechanism to cancel the centrifugal hydraulic pressure instead of the
conventional check balls. It cancels the centrifugal hydraulic pressure which is generated as high clutch drum
rotates, and it allows for preventing high clutch from dragging and for providing stable high clutch piston press-
ing force in all revolution speeds.
STRUCTURE/OPERATION
Valve name Function
Pressure regulator valve, plug and sleeve
plugRegulates oil discharged from the oil pump to provide optimum line pressure for all driving
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 driv-
ing 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.

A/T CONTROL SYSTEM
AT-35
< SERVICE INFORMATION >
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A centrifugal cancel housing is provided to cancel the clutch housing pressure. The centrifugal cancel housing
is always filled with ATF from the dedicated fluid passage of oil pump.
When Clutch Pressure Is Not Applied
As high clutch drum rotates, a centrifugal force applies to the remaining ATF in clutch housing to push high
clutch piston. However, on the other hand, the centrifugal force also applies to ATF filled in centrifugal cancel
housing, resulting in a force that pushes high clutch piston back. Consequently the high clutch piston does not
move because both forces cancel each other, and thus high clutch is prevented from dragging.
When Clutch Pressure Is Applied
Clutch pressure that applies to clutch housing overcomes the fluid pressure and spring force of the opposing
centrifugal housing to push high clutch piston, and high clutch is engaged. At this time, the centrifugal force
caused by the revolution speed of high clutch drum has no impact any more since the centrifugal force that
applies to the clutch pressure of clutch housing is canceled by the centrifugal force that applies to centrifugal
cancel housing. As a result, high clutch piston pressing force is always stable in all revolution speeds, and
thus smooth shifting characteristics are achieved.
SCIA7986E
SCIA6833E

AT-40
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
●: Solenoid ON
×: Solenoid OFF
–: Non-standard condition
Line Pressure Solenoid Valve
If non-standard solenoid signal is sent to TCM, line pressure solenoid valve is turned OFF to achieve maxi-
mum oil pressure.
Torque Converter Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, torque converter clutch solenoid valve is turned OFF to release
lock-up.
Overrun Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, overrun clutch solenoid valve is turned OFF to engage overrun
clutch. This will result in more effective engine brake during deceleration.
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000001703179
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelera-
tor pedal position sensor or PNP switch and provides shift control or
lock-up control via A/T solenoid valves.
The TCM also communicates with the ECM by means of a signal
sent from sensing elements used with the OBD-related parts of the
A/T system for malfunction-diagnostic purposes. The TCM is capa-
ble of diagnosing malfunctioning parts while the ECM can store mal-
functions in its memory.
Input and output signals must always be correct and stable in the
operation of the A/T system. The A/T system must be in good oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose a malfunction that occurs intermittently rather than continuously. Most
intermittent malfunctions are caused by poor electric connections or improper wiring. In this case, careful
checking of suspected circuits may help prevent the replacement of good parts.
Shift positionNormalMalfunction in solenoid
valve AMalfunction in solenoid
valve BMalfunction in solenoid
valves A and B
A B Gear A B Gear A B Gear A B Gear
“D” position●●1st –●→×
3rd ●→×–
3rd ––
3rd ×●2nd –●→× ×–––
××3rd – x×–––
●×4th – x●→×–––
“2” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
“1” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
SAT631IA

AT-48
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Inspections Before Trouble Diagnosis
INFOID:0000000001703182
A/T FLUID CHECK
Fluid Leakage and Fluid Level Check
Check fluid leakage and check the fluid level. Refer to MA-22, "Checking A/T Fluid".
Fluid Condition Check
Check the A/T fluid condition.
STALL TEST
Stall Test Procedure
1. Check ATF and engine oil levels. If necessary, add ATF and
engine oil.
2. Drive vehicle for approximately 10 minutes or until ATF and
engine oil reach operating temperature.
3. Set parking brake and block wheels.
4. Install a tachometer where it can be seen by driver during test.
•It is good practice to mark the point of specified engine
rpm on indicator.
5. Start engine, apply foot brake, and place selector lever in “D”
position.
Fluid status Conceivable Cause Required Operation
Varnished (viscous
varnish state)Clutch, brake
scorchedReplace the ATF and check the A/T
main unit and the vehicle for mal-
functions (wire harnesses, cooler
pipes, etc.)
Milky white or
cloudyWater in the ATFReplace the ATF and check for plac-
es where water is getting in.
Large amount of
metal powder mixed
inUnusual wear of
sliding parts within
A/TReplace the ATF and check for im-
proper operation of the A/T.
SAT638A
ATF operating temperature: 50 - 80°C (122 - 176°F)
SAT647B
SAT513G
SAT775B

TROUBLE DIAGNOSIS
AT-51
< SERVICE INFORMATION >
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Location of line pressure test ports are shown in the figure.
•Always replace pressure plugs as they are self-sealing bolts.
Line Pressure Test Procedure
1. Check ATF and engine oil levels. If necessary, add ATF or
engine oil.
2. Drive vehicle for approx. 10 minutes or until engine oil and ATF
reach operating temperature.
3. Install oil pressure gauge to corresponding line pressure test
port.
4. Set parking brake and block wheels.
5. Start engine and measure line pressure at idle and stall speed.
CAUTION:
• Keep the brake pedal pressed all the way down during
measurement.
• When measuring the line pressure at the stall speed, refer
to "STALL TEST".
SCIA7187E
ATF operating temperature: 50 - 80°C (122 -176°F)
SAT647B
SCIA6528J
SAT513G
SAT493G

AT-52
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Line Pressure
Judgement of Line Pressure Test
Road TestINFOID:0000000001703183
DESCRIPTION
• The purpose of the test is to determine overall performance of A/T
and analyze causes of malfunctions.
• The road test consists of the following three parts:
1. Check before engine is started. Refer to AT- 5 3
.
2. Check at idle. Refer to AT- 5 3
.
3. Cruise test
• Inspection all the item from Part 1 to Part 3. Refer to AT- 5 5
,
AT- 5 8
and AT- 5 9 .
Engine speedLine pressure [kPa (kg/cm
2 , psi)]
D, 2nd and 1st positions R position
Idle speed 500 (5.1, 73) 778 (7.9, 113)
Stall speed 1,173 (12.0, 170) 1,825 (18.6, 265)
Judgement Suspected parts
At idleLine pressure is low in all positions. • Oil pump wear
• Control piston damage
• Pressure regulator valve or plug sticking
• Spring for pressure regulator valve damaged
• Fluid pressure leakage between oil strainer and pressure regulator valve
• Clogged strainer
Line pressure is low in particular posi-
tion.• Fluid pressure leakage between manual valve and particular clutch
• For example, line pressure is:
− Low in “R” and “1” positions, but
− Normal in “D”, and “2” positions.
Therefore, fluid leakage exists at or around low and reverse brake circuit.
Refer to AT- 1 9 , "
Shift Mechanism".
Line pressure is high. • Accelerator pedal position signal malfunction
• A/T fluid temperature sensor damaged
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure modifier valve sticking
• Pressure regulator valve or plug sticking
• Open in dropping resistor circuit
At stall
speedLine pressure is low. • Accelerator pedal position signal malfunction
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure regulator valve or plug sticking
• Pressure modifier valve sticking
• Pilot valve sticking
SAT786A

TROUBLE DIAGNOSIS
AT-55
< SERVICE INFORMATION >
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1. Apply foot brake.
2. Move selector lever to “R” position.
Is there large shock when changing from
“N” to “R” position?
YES >> • Mark the box on the AT-40, "How to Perform Trouble
Diagnosis for Quick and Accurate Repair" .
•Go to AT-180, "
Large Shock "N" → "R" Position" .
• Continue “Road Test”.
NO >> GO TO 6.
6.CHECK VEHICLE MOVE
Release foot brake for several seconds.
Does vehicle creep backward when foot brake is released?
YES >> GO TO 7.
NO >> • Mark the box on the AT-40, "
How to Perform Trouble
Diagnosis for Quick and Accurate Repair" .
•Go to AT-181, "
Vehicle Does Not Creep Backward in
"R" Position" .
• Continue “Road Test”.
7.CHECK VEHICLE MOVE
Move selector lever to “D”, “2” and “1” positions and check if vehicle
creeps forward.
Does vehicle creep forward in all three positions?
YES >> Go to AT-55, "Cruise Test - Part 1" .
NO >> • Mark the box on the AT-40, "
How to Perform Trouble
Diagnosis for Quick and Accurate Repair" .
•Go to AT-182, "
Vehicle Does Not Creep Forward in
"D", "2" or "1" Position" .
• Continue “Road Test”.
Cruise Test - Part 1INFOID:0000000001703186
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.
SAT797A
SAT772B
SAT799A
SAT773B
ATF operating temperature: 50 - 80°C (122 - 176°F)

TROUBLE DIAGNOSIS
AT-67
< SERVICE INFORMATION >
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Slips/Will Not EngageNo creep at all.
AT- 1 8 1
, AT- 1 8 2
ON vehicle1. A/T fluid levelMA-222. Line pressure testAT- 4 8
3. Control valve assemblyAT- 2 1 6
OFF vehicle4. Forward clutchAT- 2 8 85. Oil pumpAT- 2 6 0
6. Torque converterAT- 2 4 0
Almost no shock or
clutches slipping in
change from D
1 to D2
.ON vehicle1. A/T fluid levelMA-22
2. Accelerator pedal position sensorEC-493
3. Line pressure testAT- 4 8
4. Accumulator servo releaseAT- 2 1 6
5. Control valve assemblyAT- 2 1 6
OFF vehicle 6. Brake bandAT- 3 0 7
Almost no shock or
slipping in changing
from D
2 to D3 .ON vehicle1. A/T fluid levelMA-22
2. Accelerator pedal position sensorEC-493
3. Line pressure testAT- 4 8
4. Control valve assemblyAT- 2 1 6
OFF vehicle5. High clutchAT- 2 8 46. Forward clutchAT- 2 8 8
Almost no shock or
slipping in changing
from D
3 to D4 .ON vehicle1. A/T fluid levelMA-22
2. Accelerator pedal position sensorEC-493
3. Line pressure testAT- 4 8
4. Control valve assemblyAT- 2 1 6
OFF vehicle 5. Brake bandAT- 3 0 7
Races extremely fast
or slips in changing
from D
4 to D3 when
depressing accelera-
tor pedal.ON vehicle1. A/T fluid levelMA-22
2. Accelerator pedal position sensorEC-493
3. Line pressure testAT- 4 8
4. Line pressure solenoid valveAT- 1 2 9
5. Shift solenoid valve AAT- 1 3 4
6. Control valve assemblyAT- 2 1 6
OFF vehicle7. Brake bandAT- 3 0 78. Forward clutchAT- 2 8 8
Races extremely fast
or slips in changing
from D
4 to D2 when
depressing accelera-
tor pedal.ON vehicle1. A/T fluid levelMA-22
2. Accelerator pedal position sensorEC-493
3. Line pressure testAT- 4 8
4. Line pressure solenoid valveAT- 1 2 9
5. Shift solenoid valve AAT- 1 3 4
6. Shift solenoid valve BAT- 1 3 9
7. Control valve assemblyAT- 2 1 6
OFF vehicle8. Brake bandAT- 3 0 79. Forward clutchAT- 2 8 8
Items Symptom Condition Diagnostic item Reference page