2008 NISSAN LATIO torque

CVT-24
< SERVICE INFORMATION >
CVT SYSTEM
By limiting the gear range to the lowest position, the strong driving
force and the engine brake can be secured.
DOWNHILL ENGINE BRAKE CONTROL (AUTO ENGINE BRAKE CONTROL)
When downhill is detected with the accelerator pedal released, the engine brake will be strengthened up by
downshifting so as not to accelerate the vehicle more than necessary.
ACCELERATION CONTROL
According to vehicle speed and a change of accelerator pedal angle, driver's request for acceleration and driv-
ing scene are judged. This function assists improvement in acceleration feeling by making the engine speed
proportionate to the vehicle speed. And a shift map which can gain a larger driving force is available for com-
patibility of mileage with driveability.
Lock-up and Select ControlINFOID:0000000001703444
• The torque converter clutch piston in the torque converter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
• The torque converter clutch control valve operation is controlled by the torque converter clutch solenoid
valve, which is controlled by a signal from TCM. The torque converter clutch control valve engages or
releases the torque converter clutch piston.
• When shifting between “N” (“P”) ⇔ “D” (“R”), torque converter clutch solenoid controls engagement power of
forward clutch and reverse brake.
• The lock-up applied gear range was expanded by locking up the
torque converter at a lower vehicle speed than conventional CVT
models.
TORQUE CONVERTER CLUTCH AND SELECT CONTROL VALVE CONTROL
SCIA1955E
SCIA1958E

CVT SYSTEM
CVT-25
< SERVICE INFORMATION >
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CVT
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P Lock-up and Select Control System Diagram
Lock-up Released
In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by the
torque converter clutch solenoid and the lock-up apply pressure is drained.
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 the torque
converter clutch solenoid and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
Select Control
When shifting between “N” (“P”)⇔“D” (“R”), optimize the operating pressure on the basis of the throttle posi-
tion, the engine speed, and the secondary pulley (output) revolution speed to lessen the shift shock.
Control ValveINFOID:0000000001703445
FUNCTION OF CONTROL VALVE
SCIA2374E
Name Function
Torque converter regulator valve Optimizes the supply pressure for the torque converter depending on driving conditions.
Pressure regulator valve Optimizes the discharge pressure from the oil pump depending on driving conditions.
TCC control valve• Activates or deactivate the lock-up.
• Lock-up smoothly by opening lock-up operation excessively.
TCC solenoid valve Controls the TCC control valve or select control valve.
Shift control valveControls flow-in/out of line pressure from the primary pulley depending on the stroke dif-
ference between the stepping motor and the primary pulley.
Secondary valve Controls the line pressure from the secondary pulley depending on operating conditions.
Clutch regulator valve Adjusts the clutch operating pressure depending on operating conditions.
Secondary pressure solenoid valve Controls the secondary valve.
Line pressure solenoid valve Controls the line pressure control valve.
Step motor Controls the pulley ratio.
Manual valveTransmits the clutch operating pressure to each circuit in accordance with the selected
position.
Select control valve Engages forward clutch, reverse brake smoothly depending on select operation.
Select switch valveSwitches torque converter clutch solenoid valve control pressure use to torque converter
clutch control valve or select control valve.
Lock-up select solenoid valve Controls the select switch valve.

TROUBLE DIAGNOSIS
CVT-29
< SERVICE INFORMATION >
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TROUBLE DIAGNOSIS
DTC Inspection Priority ChartINFOID:0000000001703451
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC “U1000 CAN COMM CIRCUIT” is displayed with other DTCs, first perform the trouble diagnosis
for “DTC U1000 CAN COMMUNICATION LINE”. Refer to CVT-56
.
Fail-SafeINFOID:0000000001703452
The TCM has an electrical fail-safe mode. This mode makes it possible to operate even if there is an error in a
main electronic control input/output signal circuit.
FAIL-SAFE FUNCTION
If any malfunction occurs in a sensor or solenoid, this function controls the CVT to make driving possible.
Output Speed Sensor (Secondary Speed Sensor)
The shift pattern is changed in accordance with throttle position when an unexpected signal is sent from the
output speed sensor (secondary speed sensor) to the TCM. The overdrive-off mode is inhibited, and the tran-
saxle is put in “D”.
Input Speed Sensor (Primary Speed Sensor)
The shift pattern is changed in accordance with throttle position and secondary speed (vehicle speed) when
an unexpected signal is sent from the input speed sensor (primary speed sensor) to the TCM. The sport mode
is inhibited, and the transaxle is put in “D”.
PNP Switch
If an unexpected signal is sent from the PNP switch to the TCM, the transaxle is put in “D”.
CVT Fluid Temperature Sensor
If an unexpected signal is sent from the CVT fluid temperature sensor to the TCM, the gear ratio in use before
receiving the unexpected signal is maintained or the gear ratio is controlled to keep engine speed under 3500
rpm.
Transmission Fluid Pressure Sensor A (Secondary Pressure Sensor)
• If an unexpected signal is sent from the transmission fluid pressure sensor A (secondary pressure sensor) to
the TCM, the secondary pressure feedback control is stopped and the offset value obtained before the non-
standard condition occurs is used to control line pressure.
• If transmission fluid pressure sensor A (secondary pressure sensor) error signal is input to TCM, secondary
pressure feedback control stops, but line pressure is controlled normally.
Pressure Control Solenoid A (Line Pressure Solenoid)
If an unexpected signal is sent from the solenoid to the TCM, the pressure control solenoid A (line pressure
solenoid) is turned OFF to achieve the maximum fluid pressure.
Pressure Control Solenoid B (Secondary Pressure Solenoid)
If an unexpected signal is sent from the solenoid to the TCM, the pressure control solenoid B (secondary pres-
sure solenoid) is turned OFF to achieve the maximum fluid pressure.
Torque Converter Clutch Solenoid
If an unexpected signal is sent from the solenoid to the TCM, the torque converter clutch solenoid is turned
OFF to cancel the lock-up.
Ste p M oto r
If an unexpected signal is sent from the step motor to the TCM, the step motor coil phases “A” through “D” are
all turned OFF to hold the gear ratio used right before the non-standard condition occurred.
CVT Lock-up Select Solenoid
Priority Detected items (DTC)
1 U1000 CAN communication line
2 Except above

CVT-30
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
If an unexpected signal is sent from the solenoid to the TCM, the CVT lock-up select solenoid is turned OFF to
cancel the lock-up.
TCM Power Supply (Memory Back-up)
Transaxle assembly is protected by limiting the engine torque when the memory back-up power supply (for
controlling) from the battery is not supplied to TCM. Normal statues is restored when turning the ignition switch
OFF to ON after the normal power supply.
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000001703453
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, PNP switch and provides shift control or lock-up
control via CVT 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
CVT 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 CVT system. The CVT system must be in good
operating condition and be free of valve seizure, solenoid valve mal-
function, etc.
It is much more difficult to diagnose an error that occurs intermit-
tently rather than continuously. Most intermittent errors 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.
A visual check only may not find the cause of the errors. A road test
with CONSULT-III (or GST) or a circuit tester connected should be
performed. Follow the "WORK FLOW" .
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “DIAGNOSTIC WORKSHEET” as
shown on the example (Refer to "Diagnostic Worksheet Chart" )
should be used.
Start your diagnosis by looking for “conventional” errors first. This will
help troubleshoot driveability errors on an electronically controlled
engine vehicle.
Also check related Service bulletins.
WORK FLOW
A good understanding of the malfunction conditions can make troubleshooting faster and more accurate.
In general, each customer feels differently about a malfunction. It is important to fully understand the symp-
toms or conditions for a customer complaint.
Make good use of the two sheets provided, "Information From Customer" and "Diagnostic Worksheet Chart" ,
to perform the best troubleshooting possible.
Work Flow Chart
SAT631IB
SAT632I
SEF234G

CVT-32
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Diagnostic Worksheet Chart
Customer name MR/MS Model & Year VIN
Trans. Model Engine Mileage
malfunction Date Manuf. Date In Service Date
Frequency❏ Continuous❏ Intermittent ( times a day)
Symptoms❏ Vehicle does not move. (❏ Any position❏ Particular position)
❏ No shift
❏ Lock-up malfunction
❏ Shift shock or slip (❏ N → D❏ N → R❏ Lock-up❏ Any drive position)
❏ Noise or vibration
❏ No pattern select
❏ Others
()
Malfunction indicator lamp (MIL)❏ Continuously lit❏ Not lit
1❏ Read the item on cautions concerning fail-safe and understand the customer's complaint.CVT-29
2❏ CVT fluid inspection
CVT-36❏ Leak (Repair leak location.)
❏ Sta te
❏ Amount
3❏ Stall test and line pressure test
CVT-36
,
CVT-36
❏ Stall test
❏ Torque converter one-way clutch
❏ Reverse brake
❏ Forward clutch
❏ Steel belt❏ Engine
❏ Line pressure low
❏ Primary pulley
❏ Secondary pulley
❏ Line pressure inspection - Suspected part:

CVT-38
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
6. While holding down the foot brake, gradually press down the
accelerator pedal.
7. Quickly read off the stall speed, and then quickly remove your
foot from the accelerator pedal.
CAUTION:
Do not hold down the accelerator pedal for more than 5 sec-
onds during this test.
8. Move the selector lever to the “N” position.
9. Cool down the CVT fluid.
CAUTION:
Run the engine at idle for at least 1 minute.
10. Repeat steps 6 through 9 with selector lever in “R” position.
Judgement Stall Test
O: Stall speed within standard value position.
H: Stall speed is higher than standard value.
L: Stall speed is lower than standard value.
LINE PRESSURE TEST
Line Pressure Test Port
Line Pressure Test Procedure
1. Inspect the amount of engine oil and replenish if necessary.
2. Drive the car for about 10 minutes to warm it up so that the CVT fluid reaches in the range of 50 to 80°C
(122 to 176°F), then inspect the amount of CVT fluid and replenish if necessary.
NOTE:Stall speed: 2,600 - 3,150 rpm
SAT514G
SAT771B
Selector lever position
Expected problem location
“D” “R”
Stall rotation HO•Forward clutch
O H • Reverse brake
L L • Engine and torque converter one-way clutch
HH• Line pressure low
• Primary pulley
• Secondary pulley
• Steel belt
SCIA6184E

TROUBLE DIAGNOSIS
CVT-39
< SERVICE INFORMATION >
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The CVT fluid temperature rises in the range of 50 - 80°C (122 - 176°F) during 10 minutes of driving.
3. After warming up CVT, remove the oil pressure detection plug and install the oil pressure gauge [special
service tool: - (OTC3492)].
CAUTION:
When using the oil pressure gauge, be sure to use the O-ring attached to the oil pressure detec-
tion plug.
4. Securely engage the parking brake so that the tires do not turn.
5. Start the engine, and then measure the line pressure at both idle
and the 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" .
6. After the measurements are complete, install the oil pressure
detection plug and tighten to the specified torque below.
CAUTION:
• Do not reuse O-ring.
• Apply CVT fluid to O-ring.
Line Pressure
*: Reference values
Judgement of Line Pressure Test
SAT513G
: 7.5 N·m (0.77 kg-m, 66 in-lb)SAT493G
Engine speed Line pressure kPa (kg/cm
2 , psi)
“R”, “D” and “L” positions
At idle 650 (6.63, 94.3)
At stall 4,250 (43.35, 616.3)*

TROUBLE DIAGNOSIS
CVT-45
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9.CHECK ENGINE BRAKE FUNCTION — PART 3
1. Move selector lever to “L” position.
2. Check engine brake.
Does engine braking effectively reduce speed in
“L” position?
YES >> 1. Stop the vehicle.
2. Perform self-diagnosis. Refer to CVT-47, "
CONSULT-III Function (TRANSMISSION)" .
NO >> Mark the box of CVT-159, "
Vehicle Does Not Decelerate by Engine Brake" on the CVT-30, "How
to Perform Trouble Diagnosis for Quick and Accurate Repair" . Then continue trouble diagnosis.
Vehicle Speed When Shifting GearsINFOID:0000000001703461
Numerical value data are reference values.
CAUTION:
Lock-up clutch is engaged when vehicle speed is approximately 18 km/h (11 MPH) to 90 km/h (56 MPH).
TCM Terminal and Reference ValueINFOID:0000000001703462
TCM HARNESS CONNECTOR TERMINAL LAYOUT
TERMINALS AND REFERENCE VALUES FOR TCM
Data are reference values and are measured between each terminal and ground.
Engine type Throttle position Shift patternEngine speed (rpm)
At 40 km/h (25 MPH) At 60 km/h (37 MPH)
MR18DE8/8“D” position
Overdrive-off mode
“L” position3,600 - 4,500 4,400 - 5,300
2/8“D” position 1,300 - 3,100 1,400 - 3,500
Overdrive-off mode 2,200 - 3,000 2,800 - 3,600
“L” position 3,200 - 4,100 3,900 - 4,800
WCIA0717E
Te r m i n a lWire
colorItem Condition Data (Approx.)
1GRPressure control
solenoid valve A
(Line pressure
solenoid valve)
and Release your foot from the accelerator pedal. 5.0 - 7.0 V
Press the accelerator pedal all the way down. 1.0 - 3.0 V
2LGPressure control
solenoid valve B
(Secondary
pressure sole-
noid valve) Release your foot from the accelerator pedal. 5.0 - 7.0 V
Press the accelerator pedal all the way down. 3.0 - 4.0 V
3SBTorque converter
clutch solenoid
valveWhen vehi-
cle cruises in
“D” position.When CVT performs lock-up. 6.0 V
When CVT does not perform lock-up. 1.0 V