2008 NISSAN LATIO service

A/T CONTROL SYSTEM
AT-35
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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-36
< SERVICE INFORMATION >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
ON BOARD DIAGNOSTIC (OBD) SYSTEM
IntroductionINFOID:0000000001703172
A/T system has two self-diagnostic systems.
The first is 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 but not the TCM memory.
The second is the TCM original self-diagnosis indicated by the OD OFF indicator lamp. The malfunction is
stored in the TCM memory. The detected items are overlapped with OBD-II self-diagnostic items. For detail,
refer to AT-73, "
CONSULT-III Function (A/T)" .
OBD-II Function for A/T SystemINFOID:0000000001703173
The ECM provides emission-related on board diagnostic (OBD-II) functions for the A/T system. One function
is to receive a signal from the TCM used with OBD-related parts of the A/T 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 A/T system parts.
One or Two Trip Detection Logic of OBD-IIINFOID:0000000001703174
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:0000000001703175
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
The ECM has a memory function, which stores the driving condition such as fuel system status, calculated
load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle
speed at the moment the ECM detects a malfunction.

ON BOARD DIAGNOSTIC (OBD) SYSTEM
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Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data,
and the data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-III
or GST. The 1st trip freeze frame data can only be displayed on the CONSULT-III screen, not on the GST. For
detail, refer to EC-109, "
CONSULT-II Function (ENGINE)" .
Only one set of freeze frame data (either 1st trip freeze frame data of freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no priority
for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
Both 1st trip freeze frame data and freeze frame data (along with the DTC) are cleared when the ECM mem-
ory is erased.
HOW TO ERASE DTC
The diagnostic trouble code can be erased by CONSULT-III, GST or ECM DIAGNOSTIC TEST MODE as
described following.
•If the battery cable is disconnected, the diagnostic trouble code will be cleared within 24 hours.
•When you erase the DTC, using CONSULT-III or GST is easier and quicker than switching the mode
selector on the ECM.
The following emission-related diagnostic information is cleared from the ECM memory when erasing DTC
related to OBD-II. For details, refer to EC-47, "
Emission-related Diagnostic Information" .
•Diagnostic trouble codes (DTC)
•1st trip diagnostic trouble codes (1st trip DTC)
•Freeze frame data
•1st trip freeze frame data
•System readiness test (SRT) codes
•Test values
HOW TO ERASE DTC (WITH CONSULT-III)
•If a DTC is displayed for both ECM and TCM, it is necessary to be erased for both ECM and TCM.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Turn CONSULT-III “ON” and touch “A/T”.
3. Touch “SELF-DIAG RESULTS”.
4. Touch “ERASE”. (The DTC in the TCM will be erased.) Then touch “BACK” twice.
5. Touch “ENGINE”.
6. Touch “SELF-DIAG RESULTS”.
7. Touch “ERASE”. (The DTC in the ECM will be erased.)
HOW TO ERASE DTC (WITH GST)
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Perform “TCM SELF-DIAGNOSTIC PROCEDURE (No Tools)”. Refer to AT-78, "
Diagnosis Procedure
without CONSULT-III" . (The engine warm-up step can be skipped when performing the diagnosis only to
erase the DTC.)
3. Select Mode 4 with Generic Scan Tool (GST). For details, refer to EC-119, "
Generic Scan Tool (GST)
Function" .
HOW TO ERASE DTC (NO TOOLS)
The OD OFF indicator lamp is located on the combination meter.
Priority Items
1
Freeze frame dataMisfire — DTC: P0300 - P0306
Fuel Injection System Function — DTC: P0171, P0172, P0174, P0175
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data

AT-38
< SERVICE INFORMATION >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
2. Perform “TCM SELF-DIAGNOSTIC PROCEDURE (No Tools)”. Refer to AT-78, "
Diagnosis Procedure
without CONSULT-III" . (The engine warm-up step can be skipped when performing the diagnosis only to
erase the DTC.)
3. Perform “OBD-II SELF-DIAGNOSTIC PROCEDURE (No tools)”. Refer to EC-47, "
Emission-related Diag-
nostic Information" .
Malfunction Indicator Lamp (MIL)INFOID:0000000001703176
DESCRIPTION
The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned ON with-
out the engine running. This is a bulb check.
• If the MIL does not light up, refer to DI-21
, or see EC-546 .
2. When the engine is started, the MIL should go off.
• If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction.
SEF217U

TROUBLE DIAGNOSIS
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TROUBLE DIAGNOSIS
DTC Inspection Priority ChartINFOID:0000000001703177
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
DTC “CAN COMM CIRCUIT”. Refer to AT- 8 3
.
Fail-SafeINFOID:0000000001703178
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” or “D”. The cus-
tomer may complain of sluggish or poor acceleration.
Always follow the “AT-40, "
How to Perform Trouble Diagnosis for Quick and Accurate Repair" ”.
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·A/T (Revolution Sensor)
Vehicle speed sensor·MTR signal is input from combination meter.
Accelerator Pedal Position Signal and Throttle Position Signal
TCM controls the throttle opening angle to a predetermined fixed position to enable driving if a malfunctioning
signal is input to TCM.
PNP Switch
When the multiple PNP switch signals are input to TCM, the priority of selector lever position becomes “D”,
“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.
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.
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” “D” position and other position signals D
1 ⇔D2 ⇔D3 ⇔D4
“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-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

TROUBLE DIAGNOSIS
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A visual check only, may not find the cause of the malfunctions. A
road test with CONSULT-III 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 malfunctions, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A “DIAGNOSTIC WORKSHEET”
like the example ("DIAGNOSTIC WORKSHEET" ) should be used.
Start your diagnosis by looking for “conventional” malfunctions first.
This will help troubleshoot driveability malfunctions on an electroni-
cally controlled engine vehicle.
Also check related Service bulletins for information.
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 symptoms
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
SAT632I
SEF234G

AT-42
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
DIAGNOSTIC WORKSHEET
Information from Customer
KEY POINTS
•WHAT..... Vehicle & A/T model
•WHEN..... Date, Frequencies
•WHERE..... Road conditions
•HOW..... Operating conditions, Symptoms
*1 "Information from customer" *2 "Diagnostic Worksheet Chart" *3AT- 3 9
*4AT- 4 8*5AT- 4 8, AT- 4 8*6AT- 5 2
*7AT- 7 3*8AT- 3 6*9AT- 3 9
*10AT- 9 6*11AT- 1 6 3*12AT- 1 7 3
*13AT- 6 1*14AT- 3 6*15AT- 8 3
*16AT- 1 6 3*17EC-47
SCIA7146E