2007 NISSAN LATIO low oil pressure

A/T CONTROL SYSTEM
AT-37
D
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F
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MA
B
AT
Revision: June 20062007 Versa
Control ValveUCS005MJ
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-38
A/T CONTROL SYSTEM
Revision: June 20062007 Versa
Centrifugal Cancel MechanismUCS005MK
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
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-44
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
Shift Solenoid Valve A and B
If non-standard solenoid signal is sent to TCM, use of certain gears is limited. Refer to chart shown below.

: 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.
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×–––

TROUBLE DIAGNOSIS
AT-57
D
E
F
G
H
I
J
K
L
MA
B
AT
Revision: June 20062007 Versa
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 AT-53, "
STALL TEST" .
Line Pressure
Judgement of Line Pressure Test
SAT4 9 3G
Engine speedLine pressure [kPa (kg/cm2 , 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 - 2 2 , "
CLUTCH AND BAND CHART" .
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

AT-74
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
Slips/Will Not EngageRaces extremely fast
or slips in changing
from D
3 to D2 when
depressing accelera-
tor pedal. ON vehicle1. A/T fluid levelAT- 1 6
2. Accelerator pedal position sensor EC-532
3. Line pressure testAT- 5 6
4. Line pressure solenoid valveAT- 1 4 5
5. Shift solenoid valve BAT- 1 5 6
6. Control valve assemblyAT- 2 4 2
OFF vehicle7. Brake bandAT- 3 4 38. High clutchAT- 3 1 4
Races extremely fast
or slips in changing
from D
4 or D3 to D 1
when depressing
accelerator pedal.ON vehicle1. A/T fluid levelAT- 1 6
2. Accelerator pedal position sensorEC-532
3. Line pressure testAT- 5 6
4. Line pressure solenoid valveAT- 1 4 5
5. Shift solenoid valve AAT- 1 5 1
6. Shift solenoid valve BAT- 1 5 6
7. Control valve assemblyAT- 2 4 2
OFF vehicle8. Forward clutchAT- 3 2 09. Forward one-way clutchAT- 3 3 2
10. Low one-way clutchAT- 2 6 8
Vehicle will not run in
any position.ON vehicle1. A/T fluid levelAT- 1 6
2. Control cable adjustmentAT- 2 3 3
3. Line pressure testAT- 5 6
4. Line pressure solenoid valveAT- 1 4 5
OFF vehicle5. Oil pumpAT- 2 8 9
6. High clutchAT- 3 1 4
7. Brake bandAT- 3 4 3
8. Low & reverse brakeAT- 3 2 7
9. Torque converterAT- 2 6 8
10. Parking componentsAT- 2 5 7
OthersEngine cannot be
started in “P” and “N”
positions.
AT- 2 0 0
ON vehicle1. Ignition switch and starterPG-4
, SC-10
2. Control cable adjustmentAT- 2 3 3
3. PNP switch adjustmentAT- 2 4 7
Engine starts in posi-
tions other than “P”
and “N”.ON vehicle1. Control cable adjustmentAT- 2 3 3
2. PNP switch adjustmentAT- 2 4 7
Transaxle noise in“ P”
and “N” positions.ON vehicle1. A/T fluid levelAT- 1 6
2. Line pressure testAT- 5 6
3. Accelerator pedal position sensorEC-532
4. Vehicle speed sensor·A/T (Revolution sensor)
and vehicle speed sensor·MTRAT- 1 0 7, AT- 1 6 6
OFF vehicle5. Oil pumpAT- 2 8 96. Torque converterAT- 2 6 8
Items Symptom Condition Diagnostic item Reference page

AT-76
TROUBLE DIAGNOSIS
Revision: June 20062007 Versa
OthersMaximum speed not
attained. Poor accel-
eration.ON vehicle1. A/T fluid levelAT- 1 6
2. PNP switch adjustmentAT- 2 4 6
3. Overdrive control switchAT- 1 8 6
4. Accelerator pedal position sensorEC-532
5. Vehicle speed sensor·A/T (Revolution sensor)
and vehicle speed sensor·MTRAT- 1 0 7, AT- 1 6 6
6. Shift solenoid valve AAT- 1 5 1
7. Shift solenoid valve BAT- 1 5 6
8. Control valve assemblyAT- 2 4 2
OFF vehicle9. Reverse clutchAT- 3 0 9
10. High clutchAT- 3 1 4
11. Brake bandAT- 3 4 3
12. Low & reverse brakeAT- 3 2 7
13. Oil pumpAT- 2 8 9
14. Torque converterAT- 2 6 8
Transaxle noise in
“D”, “2”, “1” and “R”
positions.ON vehicle 1. A/T fluid levelAT- 1 6
OFF vehicle 2. Torque converterAT- 2 6 8
Engine brake does
not operate in “1”
position.ON vehicle1. PNP switch adjustmentAT- 2 4 6
2. Control cable adjustmentAT- 2 3 3
3. Vehicle speed sensor·A/T (Revolution sensor)
and vehicle speed sensor·MTRAT- 1 0 7, AT- 1 6 6
4. Control valve assemblyAT- 2 4 2
5. Overrun clutch solenoid valveAT- 1 6 1
OFF vehicle6. Overrun clutchAT- 3 2 07. Low & reverse brakeAT- 3 2 7
Transaxle overheats.ON vehicle1. A/T fluid levelAT- 1 6
2. Engine idling speedEC-75
3. Accelerator pedal position sensorEC-532
4. Line pressure testAT- 5 6
5. Line pressure solenoid valveAT- 1 4 5
6. Control valve assemblyAT- 2 4 2
OFF vehicle7. Oil pumpAT- 2 8 9
8. Reverse clutchAT- 3 0 9
9. High clutchAT- 3 1 4
10. Brake bandAT- 3 4 3
11. Forward clutchAT- 3 2 0
12. Overrun clutchAT- 3 2 0
13. Low & reverse brakeAT- 3 2 7
14. Torque converterAT- 2 6 8
Items Symptom Condition Diagnostic item Reference page

AT-128
DTC P0734 A/T 4TH GEAR FUNCTION
Revision: June 20062007 Versa
DTC P0734 A/T 4TH GEAR FUNCTIONPFP:31940
DescriptionUCS005ON

This malfunction will not be detected while the OD OFF indicator lamp is indicating another self-diagnosis
malfunction.

This malfunction is detected when the A/T does not shift into fourth gear position or the torque converter
clutch does not lock up as instructed by the TCM. This is not caused by electrical malfunction (circuits
open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve
operation, malfunctioning oil pump or torque converter clutch, etc.
CONSULT-II Reference ValueUCS005OO
Remarks: Specification data are reference values.
On Board Diagnosis LogicUCS005OP

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0734 A/T 4TH GR FNCTN” with CONSULT-II is detected when A/T cannot be
shifted to the 4th gear position even if electrical circuit is good.

This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by TCM
as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is much lower than the position (4th) supposed by TCM, the slip ratio will be
much less than normal. In case the ratio does not reach the specified value, TCM judges this diagnosis
malfunction.
This malfunction will be caused when shift solenoid valve A is stuck open or shift solenoid valve B is stuck
closed.

Gear positions supposed by TCM are as follows.
In case of gear position with no malfunctions: 1, 2, 3 and 4 positions
In case of gear position with shift solenoid valve A stuck open: 2, 2, 3 and 3* positions
In case of gear position with shift solenoid valve B stuck closed: 1, 2, 2 and 1* positions to each gear
position above
*: “P0734 A/T 4TH GR FNCTN” is detected.
Possible CauseUCS005OQ

Shift solenoid valve A

Shift solenoid valve B

Line pressure solenoid valve

Each clutch

Hydraulic control circuit
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)
Item name Condition Display value (Approx.)
LINE PRES DTYSmall throttle opening (Low line pressure) ⇔ Large
throttle opening (High line pressure)0% ⇔ 94%

DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)
AT-139
D
E
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B
AT
Revision: June 20062007 Versa
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)PFP:31940
DescriptionUCS005P1

This malfunction will not be detected while the OD OFF indicator lamp is indicating another self-diagnosis
malfunction.

This malfunction is detected when the A/T does not shift into fourth gear position or the torque converter
clutch does not lock-up as instructed by the TCM. This is not caused by electrical malfunction (circuits
open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve
operation, malfunctioning oil pump or torque converter clutch, etc.
CONSULT-II Reference ValueUCS005P2
Remarks: Specification data are reference values.
On Board Diagnosis LogicUCS005P3

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0744 A/T TCC S/V FNCTN” with CONSULT-II is detected when A/T cannot per-
form lock-up even if electrical circuit is good.

This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by TCM
as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is much lower than the position (4th) supposed by TCM, the slip ratio will be
much less than normal. In case the ratio does not reach the specified value, TCM judges this diagnosis
malfunction.
This malfunction will be caused when shift solenoid valve B is stuck closed.

Gear positions supposed by TCM are as follows.
In case of gear position with no malfunctions: 1, 2, 3 and 4 positions
In case of gear position with shift solenoid valve B stuck closed: 1, 2, 2 and 1* positions to each gear posi-
tion above
*: “P0744 A/T TCC S/V FNCTN” is detected.
Possible CauseUCS005P4

Line pressure solenoid valve

Torque converter clutch solenoid valve

Each clutch

Hydraulic control circuit
Item name Condition Display value (Approx)
TCC S/V DUTY Lock-up OFF ⇔ Lock-up ON 4% ⇔ 94%