Nissan Pathfinder (2007 year). Manual - part 8

A/T CONTROL SYSTEM

AT-35

2007 Pathfinder

Shift Change System Diagram

*1: Full phase real-time feedback control monitors movement of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.

Lock-up Control

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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, and the torque converter clutch control valve engages or releases
the torque converter clutch piston.

Lock-up Operation Condition Table

TORQUE CONVERTER CLUTCH CONTROL VALVE CONTROL
Lock-up Control System Diagram

Lock-up Released

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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.

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Select lever

D position

3 position

2 position

Gear position

Lock-up

–

Slip lock-up

–

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A/T CONTROL SYSTEM

2007 Pathfinder

Lock-up Applied

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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.

SMOOTH LOCK-UP CONTROL

When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.

Half-clutched State

●

The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase
the torque converter clutch solenoid pressure.
In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put
into half-clutched status, the torque converter clutch piston operating pressure is increased and the cou-
pling is completed smoothly.

Slip Lock-up Control

●

In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the
half-clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed.
This raises the fuel efficiency for 4th and 5th gears at both low speed and when the accelerator has a low
degree of opening.

Engine Brake Control

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The forward one-way clutch transmits the drive force from the engine to the rear wheels. But the reverse
drive from the rear wheels is not transmitted to the engine because the one-way clutch is idling.
Therefore, the low coast brake solenoid is operated to prevent the forward one-way clutch from idling and
the engine brake is operated in the same manner as conventionally.

●

The operation of the low coast brake solenoid switches the low coast brake switching valve and controls
the coupling and releasing of the low coast brake.
The low coast brake reducing valve controls the low coast brake coupling force.

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A/T CONTROL SYSTEM

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2007 Pathfinder

Control Valve

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FUNCTION OF CONTROL VALVE

FUNCTION OF PRESSURE SWITCH

Name

Function

Torque converter regulator valve

In order to prevent the pressure supplied to the torque converter from being excessive,
the line pressure is adjusted to the optimum pressure (torque converter operating pres-
sure).

Pressure regulator valve
Pressure regulator plug
Pressure regulator sleeve

Adjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.

Front brake control valve

When the front brake is coupled, adjusts the line pressure to the optimum pressure
(front brake pressure) and supplies it to the front brake. (In 1st, 2nd, 3rd, and 5th gears,
adjusts the clutch pressure.)

Accumulator control valve

Adjusts the pressure (accumulator control pressure) acting on the accumulator piston
and low coast reducing valve to the pressure appropriate to the driving state.

Pilot valve A

Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for line pressure control, shift change control, and lock-up control.

Pilot valve B

Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for shift change control.

Low coast brake switching valve

During engine braking, supplies the line pressure to the low coast brake reducing valve.

Low coast brake reducing valve

When the low coast brake is coupled, adjusts the line pressure to the optimum pressure
(low coast brake pressure) and supplies it to the low coast brake.

N-R accumulator

Produces the stabilizing pressure for when N-R is selected.

Direct clutch piston switching valve

Operates in 4th gear and switches the direct clutch coupling capacity.

High and low reverse clutch control valve

When the high and low reverse clutch is coupled, adjusts the line pressure to the opti-
mum pressure (high and low reverse clutch pressure) and supplies it to the high and low
reverse clutch. (In 1st, 3rd, 4th and 5th gears, adjusts the clutch pressure.)

Input clutch control valve

When the input clutch is coupled, adjusts the line pressure to the optimum pressure
(input clutch pressure) and supplies it to the input clutch. (In 4th and 5th gears, adjusts
the clutch pressure.)

Direct clutch control valve

When the direct clutch is coupled, adjusts the line pressure to the optimum pressure
(direct clutch pressure) and supplies it to the direct clutch. (In 2nd, 3rd, and 4th gears,
adjusts the clutch pressure.)

TCC control valve
TCC control plug
TCC control sleeve

Switches the lock-up to operating or released. Also, by performing the lock-up operation
transiently, lock-up smoothly.

Torque converter lubrication valve

Operates during lock-up to switch the torque converter, cooling, and lubrication system
oil path.

Cool bypass valve

Allows excess oil to bypass cooler circuit without being fed into it.

Line pressure relief valve

Discharges excess oil from line pressure circuit.

N-D accumulator

Produces the stabilizing pressure for when N-D is selected.

Manual valve

Sends line pressure to each circuit according to the select position. The circuits to which
the line pressure is not sent drain.

Name

Function

Pressure switch 1 (FR/B)

Detects any malfunction in the front brake hydraulic pressure. When it detects any mal-
function, it puts the system into fail-safe mode.

Pressure switch 2 (LC/B)

Detects any malfunction in the low coast brake hydraulic pressure. When it detects any
malfunction, it puts the system into fail-safe mode.

Pressure switch 3 (I/C)

Detects any malfunction in the input clutch hydraulic pressure. When it detects any mal-
function, it puts the system into fail-safe mode.

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A/T CONTROL SYSTEM

2007 Pathfinder

Pressure switch 5 (D/C)

Detects any malfunction in the direct clutch hydraulic pressure. When it detects any mal-
function, it puts the system into fail-safe mode.

Pressure switch 6 (HLR/C)

Detects any malfunction in the high and low reverse clutch hydraulic pressure. When it
detects any malfunction, it puts the system into fail-safe mode.

Name

Function

ON BOARD DIAGNOSTIC (OBD) SYSTEM

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2007 Pathfinder

ON BOARD DIAGNOSTIC (OBD) SYSTEM

PFP:00028

Introduction

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The A/T 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 but not the TCM memory.
The second is the TCM original self-diagnosis indicated by the A/T CHECK 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-88, "SELF-DIAGNOSTIC RESULT MODE"

OBD-II Function for A/T System

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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-II

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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)

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HOW TO READ DTC AND 1ST TRIP DTC

DTC and 1st trip DTC can be read by the following methods.
(

with CONSULT-II or

GST) CONSULT-II or GST (Generic Scan Tool) Examples: P0705, P0720 etc.

These DTC are prescribed by SAE J2012.
(CONSULT-II 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-II can identify them as shown below, therefore, CONSULT-II (if available) is recom-
mended.

A sample of CONSULT-II display for DTC and 1st trip DTC is shown
on the next page. DTC or 1st trip DTC of a malfunction is displayed
in SELF-DIAGNOSTIC RESULTS mode for “ENGINE” with CON-
SULT-II. Time data indicates how many times the vehicle was driven
after the last detection of a DTC.

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ON BOARD DIAGNOSTIC (OBD) SYSTEM

2007 Pathfinder

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.
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-II
or GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
detail, refer to

AT-39, "ON BOARD DIAGNOSTIC (OBD) SYSTEM"

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-II, GST or ECM DIAGNOSTIC TEST MODE as
described following.

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If the battery cable is disconnected, the diagnostic trouble code will be lost within 24 hours.

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When you erase the DTC, using CONSULT-II 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-48, "EMISSION-RELATED DIAGNOSTIC INFORMATION ITEMS"

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Diagnostic trouble codes (DTC)

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1st trip diagnostic trouble codes (1st trip DTC)

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Freeze frame data

SAT015K

SAT016K

Priority

Items

Freeze frame data

Misfire — DTC: P0300 - P0306
Fuel Injection System Function — DTC: P0171, P0172, P0174, P0175

Except the above items (Includes A/T related items)

1st trip freeze frame data

ON BOARD DIAGNOSTIC (OBD) SYSTEM

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2007 Pathfinder

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1st trip freeze frame data

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System readiness test (SRT) codes

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Test values

HOW TO ERASE DTC (WITH CONSULT-II)

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If a DTC is displayed for both ECM and TCM, it is necessary to be erased for both ECM and TCM.

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.

Turn CONSULT-II “ON” and touch “A/T”.

Touch “SELF-DIAG RESULTS”.

Touch “ERASE”. (The DTC in the TCM will be erased.) Then touch “BACK” twice.

Touch “ENGINE”.

Touch “SELF-DIAG RESULTS”.

Touch “ERASE”. (The DTC in the ECM will be erased.)

HOW TO ERASE DTC (WITH GST)

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.

Select Mode 4 with the Generic Scan Tool (GST). For details refer to

EC-126, "Generic Scan Tool (GST)

Function"

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