2004 INFINITI QX56 wheel torque

A/T CONTROL SYSTEM
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Engine Brake ControlUCS002CK

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.
Control ValveUCS002CL
FUNCTION OF CONTROL VALVE
SCIA1520E
Name Function
Torque converter regulator valveIn 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 sleeveAdjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.
Front brake control valveWhen 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 valveAdjusts 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 AAdjusts the line pressure and produces the constant pressure (pilot pressure) required
for line pressure control, shift change control, and lock-up control.
Pilot valve BAdjusts 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 valveWhen 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 valveWhen 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.)

ATC-170
REFRIGERANT LINES
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BREAK-IN OPERATION
When replacing compressor clutch assembly, always conduct the break-in operation. This is done by engag-
ing and disengaging the clutch about 30 times. Break-in operation raises the level of transmitted torque.
Removal and Installation for Low-pressure Flexible HoseEJS002DL
REMOVAL
1. Remove the engine room cover using power tools.
2. Remove the engine air cleaner and air ducts. Refer to EM-14, "
REMOVAL" .
3. Remove the cowl top extension. Refer to EI-18, "
COWL TOP" .
4. Discharge the refrigerant. Refer to ATC-162, "
HFC-134a (R-134a) Service Procedure" .
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of con-
taminants.
5. Remove the low-pressure flexible hose. Refer to ATC-164, "
Components" .
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-164, "
Components" .
CAUTION:

Replace the O-ring of the low-pressure flexible hose with a new one, then apply compressor oil to
it when installing it.

After charging refrigerant, check for leaks.
Removal and Installation for High-pressure Flexible HoseEJS002DM
REMOVAL
1. Remove the engine under cover.
2. Remove the engine air cleaner and air ducts. Refer to EM-14, "
REMOVAL" .
3. Discharge the refrigerant. Refer to ATC-162, "
HFC-134a (R-134a) Service Procedure" .
4. Remove the high-pressure flexible hose. Refer to ATC-164, "
Components" .
CAUTION:
Cap or wrap the joint of the hose with suitable material such as vinyl tape to avoid the entry of
contaminants.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-164, "
Components" .
CAUTION:

Replace the O-ring of the high-pressure flexible hose with a new one, then apply compressor oil to
it when installing it.

After charging refrigerant, check for leaks.
Removal and Installation for High-pressure PipeEJ S00 2DN
REMOVAL
1. Remove the cowl top extension. Refer to EI-18, "COWL TOP" .
2. Disconnect the battery negative cable.
3. Reposition the IPDM E/R aside.
4. Remove the front right wheel and tire assembly. Refer to WT-6, "
Rotation" .
5. Position aside the front floor insulator.
6. Discharge the refrigerant. Refer to ATC-162, "
HFC-134a (R-134a) Service Procedure" .
7. Remove the low pressure pipe. Refer to ATC-171, "
Removal and Installation for Low-pressure Pipe" .
8. Remove the high-pressure pipe. Refer to ATC-164, "
Components" .
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of con-
taminants.

PRECAUTIONS
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PRECAUTIONSPFP:00001
Precautions for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT
BELT PRE-TENSIONER”
EFS003P3
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.
WA RN ING:

To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN/INFINITI dealer.

Improper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the SRS section.

Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or
harness connectors.
Precautions for Brake SystemEFS0062U

Refer to MA-10, "RECOMMENDED FLUIDS AND LUBRICANTS" for recommended brake fluid.

Do not reuse drained brake fluid.

Be careful not to splash brake fluid on painted areas.

To clean or wash all parts of master cylinder, disc brake caliper and wheel cylinder, use clean brake fluid.

Do not use mineral oils such as gasoline or kerosene. They will ruin rubber parts of the hydraulic system.

Use flare nut wrench when removing and installing brake tube.

Always check tightening torque when installing brake lines.

Before working, turn ignition switch to OFF and disconnect con-
nectors for ABS actuator and electric unit (control unit) or battery
terminals.

Burnish the brake contact surfaces after refinishing or replacing
drums or rotors, after replacing pads or linings, or if a soft pedal
occurs at very low mileage. Refer to BR-25, "
BRAKE BURNISH-
ING PROCEDURE" .
WA RN ING:

Clean brake pads and shoes with a waste cloth, then wipe
with a dust collector.SBR6 86 C

BR-22
FRONT DISC BRAKE
Revision: August 20072004 QX56
WAR NIN G:
Clean dust on cylinder body and brake pads with a vacuum dust collector to minimize the hazard of
airborne particles or other materials.
CAUTION:

While removing cylinder body never depress brake pedal because piston will pop out.

It is not necessary to remove bolts on torque member and brake hose except for disassembly or
replacement of cylinder body. In this case, hang cylinder body with a wire so as not to stretch
brake hose.

Do not damage piston boot.

Burnish brake contact surface after refinishing or replacing rotors, after replacing pads, or if a soft
pedal occurs at very low mileage. Refer to BR-25, "
BRAKE BURNISHING PROCEDURE" .
Removal and Installation of Brake PadEFS003PP
REMOVAL
1. Remove wheel and tire using power tool.
2. Remove master cylinder reservoir cap.
3. Remove lower sliding pin bolt using power tool.
4. Suspend cylinder body with a wire and remove pads, shims and retainers from torque member.
INSTALLATION
1. Apply Molykote AS880N grease between brake pad plate and shim, then attach shims to brake pads.
Refer to MA-10, "
RECOMMENDED FLUIDS AND LUBRICANTS" .
2. Attach pad retainer to torque member, then install brake pad and
shim assemblies.
CAUTION:
When attaching pad retainer, attach it firmly so that it is
flush with torque member, as shown.
3. Push pistons into cylinder body.
NOTE:
Using a disc brake piston tool (commercial service tool), etc.,
makes it easier to push in piston.
CAUTION:
By pushing in piston, brake fluid returns to master cylinder
reservoir tank. Watch the level of the surface of reservoir tank.
4. Remove wire then swing cylinder body down over brake pad assemblies.
5. Install lower sliding pin bolt and tighten to specification. Refer to BR-21, "
Components" .
6. Check brake for drag.
7. Inspect fluid level, then install master cylinder reservoir cap.
8. Install wheel and tire. Refer to WT-6, "
Rotation" .
Removal and Installation of Brake Caliper and Disc RotorEFS0062V
REMOVAL
1. Remove wheel and tire using power tool.
2. Drain brake fluid, as necessary. Refer to BR-10, "
Drain and Refill" .
NOTE:
Do not remove union bolt unless removing cylinder body from vehicle.
3. Remove union bolt as necessary and torque member bolts, then remove cylinder body and torque mem-
ber assembly.
NOTE:
Position cylinder body aside using suitable wire, as necessary.
NOTE:
When servicing cylinder body, remove sliding pin bolts and cylinder body from torque member.
4. Remove torque member, as necessary.
5. Remove disc rotor.
PFIA0273E

FRONT DISC BRAKE
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INSTALLATION
CAUTION:

Refill with new brake fluid. Refer to MA-10, "RECOMMENDED FLUIDS AND LUBRICANTS" .

Do not reuse drained brake fluid.
1. Install disc rotor.
2. Install torque member and tighten to specification. Refer to BR-21, "
Components" .
3. Install sliding pin bolts, if removed.
4. Install cylinder body, then tighten sliding pin bolts to the specified
torque. Refer to BR-21, "
Components" .
CAUTION:

When attaching cylinder body to the vehicle, wipe any oil
off knuckle spindle, washers and cylinder body attach-
ment surfaces.

Do not reuse cylinder body torque member bolts.
5. Install brake hose to cylinder body, if removed, then tighten
union bolt to the specified torque. Refer to BR-21, "
Compo-
nents" .
CAUTION:

Do not reuse copper washers for union bolt.

Attach brake hose to cylinder body together with union
bolt and washers.
6. Refill new brake fluid and bleed air. Refer to BR-11, "
Bleeding Brake System" .
7. Install wheel and tire. Refer to WT-6, "
Rotation" .
Disassembly and Assembly of Brake Caliper AssemblyEFS003PR
DISASSEMBLY
1. Remove sliding pin bolt, and then remove the pad, shim, shim cover, and pad retainer from the torque
member.
2. Remove sliding pins and sliding pin boots from torque member.
3. Place a wooden block as shown in the figure, and blow air from
union bolt mounting hole to remove pistons and piston boots.
CAUTION:
Do not get your fingers caught in piston.
LFIA0209E
LFIA0214E
MAA0272D

FRONT DISC BRAKE
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2. Apply brake fluid to piston and piston boot, then install piston
boot in to piston groove.
CAUTION:
Do not reuse piston boot.
3. Insert into cylinder body by hand and insert piston boot piston-side lip into piston groove.
CAUTION:
Press piston evenly and vary the pressing point to prevent cylinder body inner wall from being
rubbed.
4. Install sliding pins and sliding pin boots to torque member.
CAUTION:
Trailing/upper sliding pin must be replaced at each service.
5. Install cylinder body. Tighten sliding pin bolt to the specified torque. Refer to BR-21, "
Components" .
DISC ROTOR INSPECTION
Visual Inspection
Check surface of disc rotor for uneven wear, cracks, and serious damage. If any of them is detected, replace
applicable part.
Runout Inspection
1. Using wheel nuts, fix disc rotor to wheel hub at 2 or more positions.
2. Inspect runout using a dial gauge. (Measured at 10 mm (0.39 in)
inside the disc edge.)
NOTE:
Make sure that wheel bearing axial end play is within the specifi-
cations before measuring runout. Refer to FA X -5 , "
WHEEL
BEARING INSPECTION" .
3. If runout is outside the limit, find the minimum runout point by
shifting mounting positions of disc rotor and wheel hub by one
hole.
4. If runout still out of specification, turn rotor with on-car brake
lathe.
Thickness Inspection
Using a micrometer, check thickness of disc rotor. If thickness is
either at or below the wear limit, or exceeds maximum uneven wear,
replace disc rotor.
BRAKE BURNISHING PROCEDURE
Burnish brake contact surface according to the following procedure after refinishing or replacing rotors, after
replacing pads, or if a soft pedal occurs at very low mileage.
WFIA0211E
Runout limit (on vehicle) : 0.04 mm (0.0016 in)
BRA0013D
Standard thickness : 26.0 mm (1.024 in)
Repair limit thickness : 24.5 mm (0.965 in)
Maximum uneven wear
(Measured at 8 positions): 0.015 mm (0.0006 in)
SBR0 20 B

BRC-6
[VDC/TCS/ABS]
PREPARATION
Revision: August 20072004 QX56
PREPARATIONPFP:00002
Special Service ToolEFS003QG
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Commercial Service ToolsEFS003QH
Tool number
(Kent-Moore No.)
Tool nameDescription
(J-45741)
ABS active wheel sensor testerChecking operation of ABS active wheel sen-
sors
WFIA0101E
Tool nameDescription
1. Flare nut crowfoot
2. Torque wrenchRemoving and installing brake piping
a: 10mm (0.39 in)/12mm (0.47 in)
S-NT360

BRC-8
[VDC/TCS/ABS]
SYSTEM DESCRIPTION
Revision: August 20072004 QX56
ABS FunctionEFS003QJ

The Anti-Lock Brake System detects wheel revolution while braking and improves handling stability during
sudden braking by electrically preventing wheel lockup. Maneuverability is also improved for avoiding
obstacles.

If the electrical system malfunctions, the Fail-Safe function is activated, the ABS becomes inoperative and
the ABS warning lamp turns on.

The electrical system can be diagnosed using CONSULT-II.

During ABS operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is
normal.

Just after starting the vehicle, the brake pedal may vibrate or a motor operating noise may be heard from
engine compartment. This is a normal status of operation check.

Stopping distance may be longer than that of vehicles without ABS when vehicle drives on rough, gravel,
or snow-covered (fresh, deep snow) roads.
EBD FunctionEFS003QK

Electronic Brake Distribution is a function that detects subtle slippages between the front and rear wheels
during braking, and it improves handling stability by electronically controlling the brake fluid pressure
which results in reduced rear wheel slippage.

If the electrical system malfunctions, the Fail-Safe function is activated, the EBD and ABS become inoper-
ative, and the ABS warning lamp and BRAKE warning lamp are turned on.

The electrical system can be diagnosed using CONSULT-II.

During EBD operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is
normal.

Just after starting the vehicle, the brake pedal may vibrate or a motor operating noise may be heard from
engine compartment. This is a normal status of operation check.
TCS FunctionEFS003QL

Spinning of the drive wheels is detected by the ABS actuator and electric unit (control unit) using inputs
from the wheel speed sensors. If wheel spin occurs, the drive wheel right and left brake fluid pressure
control and engine fuel cut are activated while the throttle value is restricted to reduce the engine torque
and decrease the amount of wheel spin. In addition, the throttle opening is controlled to achieve the opti-
mum engine torque.

Depending on road condition, the vehicle may have a sluggish feel. This is normal, because optimum trac-
tion has the highest priority during TCS operation.

TCS may be activated during sudden vehicle acceleration, wide open throttle acceleration, sudden trans-
mission shifts or when the vehicle is driven on a road with a varying surface friction coefficient.

The SLIP indicator lamp flashes to inform the driver of TCS operation.
VDC FunctionEFS003QM

In addition to the ABS/TCS function, the driver steering amount and brake operation amount are detected
from the steering angle sensor and front and rear pressure sensors, and the vehicle's driving status
(amount of under steering/over steering) is determined using inputs from the yaw rate sensor/side G sen-
sor, wheel speed sensors, etc. and this information is used to improve vehicle stability by controlling the
braking and engine torque application to the wheels.

The SLIP indicator lamp flashes to inform the driver of VDC operation.

During VDC operation, the vehicle body and brake pedal may vibrate lightly and a mechanical noise may
be heard. This is normal.

The ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp may turn on when the vehicle is
subject to strong shaking or large vibration, such as when the vehicle is on a turn table or a ship while the
engine is running or on a steep slope. In this case, restart the engine on a normal road and if the ABS
warning lamp, VDC OFF indicator lamp and SLIP indicator lamp turn off, there is no problem.
Fail-Safe FunctionEFS003QN
CAUTION:
If the Fail-Safe function is activated, perform the Self Diagnosis for ABS/TCS/VDC system.