2008 NISSAN LATIO sensor

CVT SYSTEM
CVT-23
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Optimize the line pressure and secondary pressure, depending on driving conditions, on the basis of the throt-
tle position, the engine speed, the primary pulley (input) revolution speed, the secondary pulley (output) revo-
lution speed, the brake signal, the PNP switch signal, the lock-up signal, the voltage, the target gear ratio, the
fluid temperature, and the fluid pressure.
FEEDBACK CONTROL
When controlling the normal fluid pressure or the selected fluid pressure, the secondary pressure can be set
more accurately by using the fluid pressure sensor to detect the secondary pressure and controlling the feed-
back.
Shift ControlINFOID:0000000001703443
In order to select the gear ratio which can obtain the driving force in accordance with driver's intention and the
vehicle condition, TCM monitors the driving conditions, such as the vehicle speed and the throttle position and
selects the optimum gear ratio, and determines the gear change steps to the gear ratio. Then send the com-
mand to the step motor, and control the flow-in/flow-out of line pressure from the primary pulley to determine
the position of the moving-pulley and control the gear ratio.
NOTE:
The gear ratio is set for every position separately.
“D” POSITION
Shifting over all the ranges of gear ratios from the lowest to the high-
est.
OVERDRIVE-OFF MODE
Use this position for the improved engine braking.
“L” POSITION
SCIA7958E
SCIA1953E

CVT-26
< SERVICE INFORMATION >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
ON BOARD DIAGNOSTIC (OBD) SYSTEM
IntroductionINFOID:0000000001703446
The CVT system has two self-diagnostic systems.
The first is the emission-related on board diagnostic system (OBD-II) performed by the TCM in combination
with the ECM. The malfunction is indicated by the MIL (malfunction indicator lamp) and is stored as a DTC in
the ECM memory, and the TCM memory.
The second is the TCM original self-diagnosis performed by the TCM. The malfunction is stored in the TCM
memory. The detected items are overlapped with OBD-II self-diagnostic items. For detail, refer to CVT-47,
"CONSULT-III Function (TRANSMISSION)".
OBD-II Function for CVT SystemINFOID:0000000001703447
The ECM provides emission-related on board diagnostic (OBD-II) functions for the CVT system. One function
is to receive a signal from the TCM used with OBD-related parts of the CVT system. The signal is sent to the
ECM when a malfunction occurs in the corresponding OBD-related part. The other function is to indicate a
diagnostic result by means of the MIL (malfunction indicator lamp) on the instrument panel. Sensors, switches
and solenoid valves are used as sensing elements.
The MIL automatically illuminates in One or Two Trip Detection Logic when a malfunction is sensed in relation
to CVT system parts.
One or Two Trip Detection Logic of OBD-IIINFOID:0000000001703448
ONE TRIP DETECTION LOGIC
If a malfunction is sensed during the first test drive, the MIL will illuminate and the malfunction will be stored in
the ECM memory as a DTC. The TCM is not provided with such a memory function.
TWO TRIP DETECTION LOGIC
When a malfunction is sensed during the first test drive, it is stored in the ECM memory as a 1st trip DTC
(diagnostic trouble code) or 1st trip freeze frame data. At this point, the MIL will not illuminate. — 1st trip
If the same malfunction as that experienced during the first test drive is sensed during the second test drive,
the MIL will illuminate. — 2nd trip
The “trip” in the “One or Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation.
OBD-II Diagnostic Trouble Code (DTC)INFOID:0000000001703449
HOW TO READ DTC AND 1ST TRIP DTC
DTC and 1st trip DTC can be read by the following methods.
( with CONSULT-III or GST) CONSULT-III or GST (Generic Scan Tool) Examples: P0705, P0720 etc.
These DTC are prescribed by SAE J2012.
(CONSULT-III also displays the malfunctioning component or system.)
•1st trip DTC No. is the same as DTC No.
•Output of the diagnostic trouble code indicates that the indicated circuit has a malfunction. How-
ever, in case of the Mode II and GST, they do not indicate whether the malfunction is still occurring or
occurred in the past and returned to normal.
CONSULT-III can identify them as shown below, therefore, CONSULT-III (if available) is recom-
mended.
DTC or 1st trip DTC of a malfunction is displayed in SELF-DIAGNOSTIC RESULTS mode for “ENGINE” with
CONSULT-III. Time data indicates how many times the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be “0”.
If a 1st trip DTC is stored in the ECM, the time data will be “1t”.
Freeze Frame Data and 1st Trip Freeze Frame Data

TROUBLE DIAGNOSIS
CVT-29
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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

TROUBLE DIAGNOSIS
CVT-35
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CVT Electrical Parts LocationINFOID:0000000001703454
1. O/D OFF indicator lamp 2. Shift position indicator 3. Accelerator pedal position sensor
4. CVT unit harness connector 5. Fuel door release 6. TCM
7. Overdrive control switch
BCIA0033E

CVT-40
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Road Test
INFOID:0000000001703457
DESCRIPTION
• The purpose of the test is to determine overall performance of CVT
and analyze causes of problems.
• The road test consists of the following three parts:
1. “Check Before Engine Is Started”CVT-41
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2. “Check at Idle”CVT-41
.
3. “Cruise Test”CVT-43
.
Judgement Possible cause
Idle speedLow for all positions
(“P”, “R”, “N”, “D”, “L”)Possible causes include malfunctions in the pressure supply system and low oil pump output.
For example
•Oil pump wear
• Pressure regulator valve or plug sticking or spring fatigue
•Oil strainer ⇒ oil pump ⇒ pressure regulator valve passage oil leak
• Engine idle speed too low
Only low for a specific
positionPossible causes include an oil pressure leak in a passage or device related to the position after
the pressure is distributed by the manual valve.
HighPossible causes include a sensor malfunction or malfunction in the line pressure adjustment
function.
For example
• Accelerator pedal position signal malfunction
• CVT fluid temperature sensor malfunction
• Pressure control solenoid A (line pressure solenoid) malfunction (sticking in OFF state, filter
clog, cut line)
• Pressure regulator valve or plug sticking
Sta ll sp ee dLine pressure does
not rise higher than
the line pressure for
idle.Possible causes include a sensor malfunction or malfunction in the pressure adjustment func-
tion.
For example
• Accelerator pedal position signal malfunction
•TCM malfunction
• Pressure control solenoid A (line pressure solenoid) malfunction (shorting, sticking in ON
state)
• Pressure regulator valve or plug sticking
The pressure rises,
but does not enter the
standard position.Possible causes include malfunctions in the pressure supply system and malfunction in the pres-
sure adjustment function.
For example
• Accelerator pedal position signal malfunction
• Pressure control solenoid A (line pressure solenoid) malfunction (sticking, filter clog)
• Pressure regulator valve or plug sticking
Only low for a specific
positionPossible causes include an oil pressure leak in a passage or device related to the position after
the pressure is distributed by the manual valve.
SAT786A

CVT-46
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
4BRLock-up select
solenoid valveSelector lever in “P” and “N” positions Battery voltage
Wait at least for 5 seconds with the selector lever in
“R”, “D” and “L” positions0 V
5 L CAN-H — —
6 P CAN-L — —
8VBack-up lamp
relaySelector lever in “R” position. 0 V
Selector lever in other positions. Battery voltage
10 R Power supply— Battery voltage
—0 V
11 L Step motor A Within 2 seconds after ignition switch ON, the time measurement by using
the pulse width measurement function (Hi level) of CONSULT-III.*1
*1: A circuit tester cannot be used to test this item.30.0 msec
12 Y Step motor B10.0 msec
13 G ROM assembly — —
14 Y ROM assembly — —
15 G ROM assembly — —
19 R Power supply— Battery voltage
—0 V
20 W Step motor C Within 2 seconds after ignition switch ON, the time measurement by using
the pulse width measurement function (Hi level) of CONSULT-III.*1
*1: A circuit tester cannot be used to test this item.30.0 msec
21 P Step motor D10.0 msec
24 BR Starter relaySelector lever in “N” and “P”positions. Battery voltage
Selector lever in other positions. 0 V
25 B Ground Always 0 V
27 GR PNP switch 1Selector lever in “R”, “N” and “D” positions. 0 V
Selector lever in “P” and “L” positions. Battery voltage
28 YPower supply
(memory back-
up)Always Battery voltage
29 ROutput speed
sensor (Second-
ary speed sen-
sor)When driving [“D” position, 20 km/h (12 MPH)]. 570 Hz
31 LG K-LINE — — Te r m i n a lWire
colorItem Condition Data (Approx.)

TROUBLE DIAGNOSIS
CVT-47
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CONSULT-III Function (TRANSMISSION)INFOID:0000000001703463
CONSULT-III can display each diagnostic item using the diagnostic test modes shown below.
FUNCTION
32 YPNP switch 3
(monitor)Selector lever in “D” and “L” positions. 0 V
Selector lever in “P”, “R” and “N” positions.8.0 V - Battery
voltage
34 SB PNP switch 2Selector lever in “N”, “D” and “L” positions. 0 V
Selector lever in “P” and “R” positions.10.0 V - Battery
voltage
35 W PNP switch 3Selector lever in “D” and “L” positions. 0 V
Selector lever in “P”, “R” and “N” positions.8.0 V - Battery
voltage
36 W PNP switch 4Selector lever in “R” and “D” positions. 0 V
Selector lever in “P”, “N” and “L” positions.10.0 V - Battery
voltage
37 LTransmission
fluid pressure
sensor A (Sec-
ondary pressure
sensor)and “N” position idle 1.0 V
38 VInput speed sen-
sor (Primary
speed sensor)When driving [“L” position, 20 km/h (12 MPH)]. 1000 Hz
41 GTransmission
fluid pressure
sensor B (Prima-
ry pressure sen-
sor)and “N” position idle 0.7 V
42 LG Sensor ground Always 0 V
46 O Sensor power— 5.0 V
— 0 V
47 GCVT fluid tem-
perature sensor When CVT fluid temperature is 20°C (68°F) 2.0 V
When CVT fluid temperature is 80°C (176°F) 1.0 V
48 B Ground Always 0 V Te r m i n a lWire
colorItem Condition Data (Approx.)
Diagnostic test mode Function
Work supportThis mode enables a technician to adjust some devices faster and more accurately by following the in-
dications on CONSULT-III.
Self-diagnostic results Self-diagnostic results can be read and erased quickly.
Data monitor Input/Output data in the TCM can be read.