2003 NISSAN X-TRAIL wheel torque

OVERALL SYSTEM
AT-37
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TORQUE CONVERTER CLUTCH SOLENOID VALVE CONTROL
Lock-up 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 applying pressure is drained and the torque converter clutch piston
release pressure is generated.
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 applying pressure is generated and the torque converter clutch piston
release pressure is drained.
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 steadily increase the
torque converter clutch solenoid pressure.
In this way, the lock-up applying 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
coupling is completed smoothly.
Engine Brake Control (Overrun Clutch Control)ECS00CTF
Forward one-way clutch is used to reduce shifting shocks in downshifting operations. This clutch transmits
engine torque to the wheels. However, drive force from the wheels is not transmitted to the engine because
the one-way clutch rotates idle. This means the engine brake is not effective.
The overrun clutch operates when the engine brake is needed.
SCIA5623E

TF-2 DIAGNOSTIC PROCEDURE .............................. 40
COMPONENT INSPECTION .............................. 42
Engine Control Signal ............................................. 42
DIAGNOSTIC PROCEDURE .............................. 42
CAN Communication Line ...................................... 43
DIAGNOSTIC PROCEDURE .............................. 43
TROUBLE DIAGNOSIS FOR SYMPTOMS .............. 44
4WD Indicator Lamp and LOCK Indicator Lamp Do
Not Turn ON for Approx. 1 Second When The Igni-
tion Switch Is Turned to ON .................................... 44
DIAGNOSTIC PROCEDURE .............................. 44
4WD Warning Lamp Does Not Turn ON When The
Ignition Switch Is Turned to ON .............................. 45
DIAGNOSTIC PROCEDURE .............................. 45
4WD Warning Lamp Does Not Turn OFF Several
Seconds after Engine Started ................................. 46
DIAGNOSTIC PROCEDURE .............................. 46
4WD Mode Cannot Be Switched after Engine Is
Started .................................................................... 47
DIAGNOSTIC PROCEDURE .............................. 47
Heavy Tight-corner Braking Symptom Occurs
When The Vehicle Is Driven in AUTO Mode and The
Steering Wheel Is Turned Fully to Either Side after
The Engine Is Started ............................................. 48
DIAGNOSTIC PROCEDURE .............................. 48
Vehicle Does Not Enter 4WD Mode Even Though
4WD Warning Lamp Turned to OFF ....................... 49
DIAGNOSTIC PROCEDURE .............................. 50
While Driving, 4WD Warning Lamp Flashes Rapidly
(When Flashing in Approx. 1 Minute and Then Turn-
ing OFF) ................................................................. 50
While Driving, 4WD Warning Lamp Flashes Slowly
(When Continuing to Flash until Turning Ignition Switch OFF) ............................................................ 51
DIAGNOSTIC PROCEDURE ............................... 51
4WD CONTROL UNIT ............................................... 52
Removal and Installation ......................................... 52
REMOVAL ............................................................ 52
INSTALLATION .................................................... 52
SIDE OIL SEAL ......................................................... 53
Removal and Installation ......................................... 53
REMOVAL ............................................................ 53
INSTALLATION .................................................... 53
AIR BREATHER HOSE ............................................. 54
Components ............................................................ 54
Removal and Installation ......................................... 54
TRANSFER ASSEMBLY ........................................... 55
Removal and Installation ......................................... 55
COMPONENTS ................................................... 55
REMOVAL ............................................................ 55
INSTALLATION .................................................... 56
Disassembly and Assembly .................................... 57
COMPONENTS ................................................... 57
ASSEMBLY INSPECTION ................................... 58
DISASSEMBLY .................................................... 62
INSPECTION AFTER DISASSEMBLY ................ 66
SELECTING ADJUSTING SHIMS ....................... 67
ASSEMBLY .......................................................... 68
SERVICE DATA AND SPECIFICATIONS (SDS) ...... 74
General Specifications ............................................ 74
Inspection and Adjustment ...................................... 74
PRELOAD TORQUE BEFORE DISASSEMBLY ... 74
PRELOAD TORQUE AFTER DISASSEMBLY
AND REASSEMBLY ............................................ 74
BACKLASH .......................................................... 74
COMPANION FLANGE RUNOUT ....................... 74
SELECTIVE PARTS ............................................ 74

TF-10
ALL MODE 4X4 SYSTEM

ALL MODE 4X4 SYSTEMPFP:47850
Power Transfer DiagramEDS001VA
System DescriptionEDS001VB
ELECTRIC CONTROLLED COUPLING
Operation Principle
1. The 4WD control unit supplies command current to electric con-
trolled coupling (4WD solenoid).
2. The control clutch is engaged by electromagnet and torque is
detected in control clutch.
3. The cam operates in response to control clutch torque and
applies pressure to main clutch.
4. The main clutch transmits torque to front wheels according to
pressing power.

Transmission torque to the rear wheels is determined accord-
ing to command current.
4WD CONTROL UNIT

4WD controls distribution of drive power between front-wheel
drive (100:0) and 4WD (50:50) conditions according to signals
from sensors.

Self-diagnosis can be done with CONSULT-II.
SDIA1607E
SFIA0284E
SDIA1844E
SDIA2285E

ALL MODE 4X4 SYSTEM
TF-11
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4WD MODE SWITCH
AUTO Mode

Electronic control allows optimal distribution of torque to front/rear wheels to match road conditions.

4WD mode makes possible stable driving, with no wheel spin, on snowy roads or other slippery surfaces.

On roads which do not require 4WD, AUTO mode contributes to improved fuel economy by driving in con-
ditions close to front-wheel drive.

Sensor inputs determine the vehicle's turning condition, and tight cornering/braking are controlled by dis-
tributing optimum torque to rear wheels.
LOCK Mode

Front/rear wheel torque distribution is fixed, ensuring stable driving when climbing slopes.

Vehicle will switch automatically to AUTO mode if vehicle speed increases. If vehicle speed then
decreases, the vehicle automatically returns to direct 4-wheel driving conditions.

LOCK mode will change to AUTO mode automatically, when the vehicle speed exceeds approx. 30 km/h
(19 MPH). The LOCK indicator light keeps illuminating.
NOTE:
If there is a significant difference in pressure or wear between tires, full vehicle performance is not available.
LOCK mode may be prohibited, or speeds at which LOCK mode is enabled may be restricted detecting tire
conditions.
2WD Mode
Vehicle is in front-wheel drive.
NOTE:

If front wheels are slipping in 2WD mode, do not switch to AUTO or LOCK. This can cause difficulties for
the system.

Even if the 4WD mode switch is in 2WD mode, the 4WD control unit occasionally automatically change to
AUTO mode depending on the driving condition (For example; Depressing the acceleration firmly). This is
not malfunction. However, 4WD indicator lamp dose not illuminate.
4WD INDICATOR LAMP AND LOCK INDICATOR LAMP
The following is the indications of indicator lamp.
4WD WARNING LAMP
Turns ON when there is a malfunction in 4WD system. It indicates that the vehicle is in fail-safe mode and
change to front-wheel drive or shifting driving force-4WD (Rear-wheels still have some driving torque).
Also turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF approximately for 1
seconds after the engine starts if system is normal.
4WD Warning Lamp Indication
Condition 4WD indicator lamp LOCK indicator lamp
AUTO mode ON OFF
LOCK mode ON ON
2WD mode OFF OFF
Lamp check Turns ON for approx. 1 second when ignition switch is turned ON.
SDIA2298E
Condition 4WD warning lamp
Lamp checkTurns ON when ignition switch is turned ON. Turns OFF
approx. 1 seconds after engine start.
4WD system malfunctionON
Protection function is activated due to heavy load to electric con-
trolled coupling. (4WD system is not malfunctioning and 4WD system
changes to 2WD mode.)Rapid flashing: 2 times/second
(Flashing in approx. 1 minute and then turning OFF.)

ALL MODE 4X4 SYSTEM
TF-13
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COMPONENTS FUNCTION DESCRIPTION
CAN CommunicationEDS0027K
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
CAN COMMUNICATION UNIT (M/T MODELS WITHOUT ESP)
System diagram
Component parts Function
4WD control unit

Controls driving force distribution by signals from each sensor and switch from front wheel driving
mode (100:0) to 4WD mode (50:50).

2WD mode is available by fail-safe function if malfunction is detected in electrical system.
Wheel sensors Detects wheel speed.
4WD solenoid Controls electric controlled coupling by operation signal from 4WD control unit.
Electric controlled coupling Transmits driving force to rear final drive.
4WD mode switch Able to select from 2WD, AUTO or LOCK mode.
4WD warning lamp

Illuminates if malfunction is detected in electrical system of 4WD system.

There is 1 blink in 2 seconds if rotation difference of front wheels and rear wheels is large.

There are 2 blinks in 1 second if load is still applied to driving parts.
4WD indicator lamp Indicate operation with optimal distribution of torque to front/rear wheels.
LOCK indicator lamp Indicate that 4WD system is under direct 4-wheel driving mode.
ABS actuator and electric unit
(control unit) (without ESP) or
ESP/TCS/ABS control unit (with
ESP)Transmits the following signals via CAN communication to 4WD control unit.

Vehicle speed signal

Stop lamp switch signal (brake signal)
ECMTransmits the following signals via CAN communication to 4WD control unit.

Accelerator pedal position signal

Engine speed signal
Unified meter control unit Transmits conditions of parking brake switch via CAN communication to 4WD control unit.
PKIA6458E

TF-18
TROUBLE DIAGNOSIS

TROUBLE DIAGNOSISPFP:00004
Fail-safe FunctionEDS001VE

If any malfunction occurs in 4WD electrical system, and control unit detects the malfunction, 4WD warning
lamp on combination meter turns ON to indicate system malfunction.

When 4WD warning lamp is ON, vehicle changes to front-wheel drive or shifting driving force-4WD (Rear-
wheels still have some driving torque).
How to Perform Trouble DiagnosisEDS001VF
BASIC CONCEPT

To perform trouble diagnosis, it is the most important to have understanding about vehicle systems (con-
trol and mechanism) thoroughly.

It is also important to clarify customer complaints before inspec-
tion.
First of all, reproduce symptoms, and understand them fully.
Ask customer about his/her complaints carefully. In some cases,
it will be necessary to check symptoms by driving vehicle with
customer.
CAUTION:
Customers are not professional. It is dangerous to make an
easy guess like "maybe the customer means that...," or
"maybe the customer mentions this symptom".

It is essential to check symptoms right from the beginning in
order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms based on
interview with customer and past examples. Do not perform
inspection on ad hoc basis. Most intermittent malfunctions are
caused by poor contacts. In this case, it will be effective to shake
suspected harness or connector by hand. When repairing with-
out any symptom diagnosis, you cannot judge if malfunctions
have actually been eliminated.

After completing diagnosis, always erase diagnostic memory.
Refer to TF-31, "
How to Erase Self-diagnostic Results" .

For intermittent malfunctions, move harness or harness connec-
tor by hand. Then check for poor contact or reproduced open circuit.
SEF233G
SEF234G

PR-2
NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTING

NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTINGPFP:00003
NVH Troubleshooting ChartEDS0027A
Use the chart below to help you find the cause of the symptom. If necessary, repair or replace these parts.
×: ApplicableReference page
—
PR-6—
—
—
PR-3—
NVH in RFD section
NVH in FAX, RAX, FSU, and RSU section
NVH in WT section
NVH in WT section
NVH in FAX and RAX section
NVH in BR section
NVH in PS section
Possible cause and SUSPECTED PARTS
Uneven rotating torque
Center bearing improper installation
Excessive center bearing axial end play
Center bearing mounting (insulator) cracks, damage or deterioration
Excessive joint angle
Rotation imbalance
Excessive runout
DIFFERENTIAL
AXLE AND SUSPENSION
TIRES
ROAD WHEEL
DRIVE SHAFT
BRAKES
STEERING
SymptomNoise××××××××××××××
Shake× × ××××××
Vibration××××××× ×× × ×

FRONT WHEEL HUB AND KNUCKLE
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FRONT WHEEL HUB AND KNUCKLEPFP:40202
On-Vehicle InspectionEDS0005R
Inspect to check that there is no excessive play, cracking, wear, or
other damage to front axle.

Turn front wheels (left/right) and check the play.

Check that no nails or other foreign objects are embedded.

Retighten all axle nuts and bolts to the specified torque.
FRONT WHEEL BEARINGS
With the vehicle raised, inspect the following.

Move wheel hub in the axial direction by hand. Check that there is no looseness of front wheel bearings.

Rotate wheel hub and check that there is no unusual noise or other irregular conditions. If there are any
irregular conditions, replace the wheel bearing.
Removal and InstallationEDS0005S
REMOVAL
1. Remove tyre. Remove brake hose lock plate from strut.
2. Remove brake caliper from steering knuckle. Hang it in a place where it will not interfere with work. Refer
to BR-27, "
FRONT DISC BRAKE" .
CAUTION:
Avoid depressing the brake pedal with brake caliper removed.
3. Remove wheel sensor from steering knuckle. Refer to BRC-116, "
WHEEL SENSORS" .
CAUTION:
Do not pull on wheel sensor harness.
SMA525A
Axial end play : 0.05 mm (0.002 in)
1. Steering knuckle 2. Splash guard 3. Wheel bearing assembly
4. Snap ring 5. Wheel hub 6. Hub bolt
7. Cotter pin
SDIA0131E