2011 INFINITI QX56 oil pressure

ST-58
< SERVICE DATA AND SPECIFICATIONS (SDS)
SERVICE DATA AND SPECIFICATIONS (SDS)
Steering Shaft Sliding Range
INFOID:0000000006225625
Unit: mm (in)
Rack Sliding ForceINFOID:0000000006225626
Unit: N (kg, lb)
Rack StrokeINFOID:0000000006225627
Unit: mm (in)
Socket Swing Force and Rotating TorqueINFOID:0000000006225628
SWING FORCE
Unit: N (kg, lb)
ROTATING TORQUE
Unit: N·m (kg-m, in-lb)
Socket Axial End PlayINFOID:0000000006225629
Unit: mm (in)
Inner Socket LengthINFOID:0000000006225630
Unit: mm (in)
Relief Oil PressureINFOID:0000000006225631
Unit: kPa (bar, kg/cm2, psi)
Item Standard
Sliding range 47 (1.85)
Steering shaft length (extended position) 393 (15.47) or less
Steering shaft runout 1.5 (0.059) or less
Item Standard
Rack sliding force 249.6 – 308.4 (25.5 – 31.4, 56.2 – 69.3)
Item Standard
Rack neutral position, dimension 83.5 (3.287)
Item Spring balance
Outer socket 10.0 – 36.7 (1.02 – 3.74, 2.25 – 8.25)
Inner socket 19.4 – 32.3 (1.98 – 3.29, 4.37 – 7.26)
Item Standard
Outer socket 0.3 – 2.9 (0.03 – 0.3, 2.7 – 26)
Item Standard
Outer socket 0.5 (0.02) or less
Inner socket 0.2 (0.008) or less
Item Standard
Rack neutral position, dimension 110.8 (4.36)
Item Standard
Relief oil pressure 9,500 – 10,300 (95 – 103, 96.9 – 105.1, 1,378 – 1,494)
Revision: 2010 May2011 QX56

STC-4
< SYSTEM DESCRIPTION >
COMPONENT PARTS
SYSTEM DESCRIPTION
COMPONENT PARTS
Component Parts LocationINFOID:0000000006256115
Component DescriptionINFOID:0000000006256116
Power Steering Control UnitINFOID:0000000006256117
 Signals from various sensors control the driving voltage to the power steering solenoid valve.
 The power steering control unit controls the driving vo ltage to the power steering solenoid valve for maintain-
ing the power steering assist force when the fail-safe function is activated. (The engine speed signals control
EPS system if any vehicle s peed signal error is detected.)
Power Steering Solenoid ValveINFOID:0000000006256118
Power steering solenoid valve controls the power steering oil pressure in the gear housing assembly.
1. ECM
Refer to EC-16, "
Component Parts
Location". 2. Combination meter
Refer to MWI-6, "
METER SYSTEM :
Component Parts Location". 3. Power steering control unit
4. Power steering solenoid valve
A. Glove box assembly removed B. Steering gear assembly
JPGIB0006ZZ
Component parts Reference/Function
Power steering control unit STC-4, "
Power Steering Control Unit"
Power steering solenoid valveSTC-4, "Power Steering Solenoid Valve"
Combination meter Transmits vehicle speed signal to power steering control unit.
ECM Transmits engine speed signal to power steering control unit.
Revision: 2010 May2011 QX56

STC-6
< SYSTEM DESCRIPTION >
SYSTEM
OPERATION PRINCIPLE
During Parking (When Turning The Steering Wheel To The Right.)
1. Power steering solenoid valve is closed while a vehicle is stopped.
2. Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.
3. Oil pressure “P” in the gear housing assembly is the sum of oil pressures occurred in “2R” and “3R”. Thisresults in a light steering force because of high pressure.
During High-speed Operation
1. Power steering solenoid valve is opened during high-speed operation.
2. Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.
3. Oil pressure “2R” does not occur because the pow er steering solenoid valve is on full throttle.
4. Oil pressure “P” in the gear housing assembly includes only oil pressure occurred in “3R” and results in a heavy steering force.
EPS SYSTEM : Fail-Safe INFOID:0000000006256120
EPS system
 EPS system enters the fail-safe mode (that allows the steering
force to be controlled without impairi ng the drivability) if any of the
input/output values to/from EPS system (power steering control
unit) deviate from the standard range.
 The power steering control unit controls the driving voltage to the
power steering solenoid valve for maintaining the power steering
assist force when the fail-safe function is activated. (The engine
speed signals control EPS system if any vehicle speed signal error
is detected.)
1. Combination meter 2. Power steering control unit 3. Power steering solenoid valve
4. Steering gear assembly 5. Gear housing assembly 6. Gear sub-assembly
7. Pinion 8. Power steering oil pump 9. Reservoir tank
JSGIA0020GB
JSGIA0021GB
JPGIB0022GB
Revision: 2010 May2011 QX56

DIAGNOSIS AND REPAIR WORK FLOWSTC-13
< BASIC INSPECTION >
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BASIC INSPECTION
DIAGNOSIS AND REPAIR WORK FLOW
Work FlowINFOID:0000000006256124
DETAILED FLOW
1.COLLECT THE INFORMATION FROM THE CUSTOMER
It is also important to clarify customer complaints before inspection. First of all, reproduce symptoms and
understand them fully. Ask customer about his/her complaints carefully. In some cases, it is necessary to
check symptoms by driving vehicle with customer.
CAUTION:
Customers are not professional. It is danger ous to make an easy guess like “maybe the customer
means that...,” or “maybe the cu stomer mentions this symptom”.
>> GO TO 2.
2.CHECK THE STATUS
1. Power steering fluid leakage and check the power steering fluid level. Refer to ST-30, "
Inspection".
2. Check the drive belt tension. Refer to EM-20, "
Checking".
3. Check the power steering gear for damages, cracks and fluid leakage. Refer to ST-46, "
Inspection".
4. Check the relief oil pressure. Refer to ST-52, "
Inspection".
>> GO TO 3.
3.DIAGNOSIS CHART BY SYMPTOM
Perform the diagnosis by symptom. Refer to STC-22, "
Diagnosis Procedure".
>> GO TO 4.
4.FINAL CHECK
Check the input/output standard values for the power steering control unit.
Are the power steering control unit input/output values within standard ranges respectively?
YES >> INSPECTION END
NO >> GO TO 2.
Revision: 2010 May2011 QX56

COMPONENT PARTSTM-13
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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A/T CONTROL SYSTEM : High and Lo w Reverse Clutch Solenoid ValveINFOID:0000000006226748
 The high and low reverse clutch solenoid valve is controlled by the TCM in response to signals transmitted
from the transmission range switch, output speed sens or and accelerator pedal position sensor. Gears will
then be shifted to the optimum position.
 The high and low reverse clutch solenoid valve controls the high and low reverse clutch control valve in response to a signal transmitted from the TCM.
A/T CONTROL SYSTEM : Lo w Brake Solenoid ValveINFOID:0000000006226749
 The low brake solenoid valve is controlled by the TC M in response to signals transmitted from the transmis-
sion range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to
the optimum position.
 The low brake solenoid valve controls the low brake control valve in response to a signal transmitted from
the TCM.
A/T CONTROL SYSTEM : Anti-interlock Solenoid ValveINFOID:0000000006226750
 Anti-interlock solenoid valve prevents the simultaneous activation of the input clutch and the low brake.
 The anti-interlock solenoid valve is an ON/OFF type solenoid valve.
A/T CONTROL SYSTEM : 2 346 Brake Solenoid ValveINFOID:0000000006226751
 The 2346 brake solenoid valve is controlled by the TC M in response to signals transmitted from the trans-
mission range switch, output speed sensor and accelera tor pedal position sensor. Gears will then be shifted
to the optimum position.
 The 2346 brake solenoid valve controls the 2346 brake c ontrol valve in response to a signal transmitted from
the TCM.
A/T CONTROL SYSTEM : Torque Co nverter Clutch Solenoid ValveINFOID:0000000006226752
The torque converter clutch solenoid va lve is activated, with the gear in D2, D3, D4, D5, D6, D7, M2, M3, M4,
M5, M6 and M7 by the TCM in response to signals tr ansmitted from the output speed sensor and accelerator
pedal position sensor. Torque converter clut ch piston operation will then be controlled.
A/T CONTROL SYSTEM : Line Pressure Solenoid ValveINFOID:0000000006226753
The line pressure solenoid valve regulates the oil pum p discharge pressure to suit the driving condition in
response to a signal transmitted from the TCM.
A/T CONTROL SYSTEM : Accele rator Pedal Position SensorINFOID:0000000006226754
 The accelerator pedal position sensor is installed on the upper end of the accelerator pedal assembly.
 The accelerator pedal position sensor detects the accelerator position.
 The accelerator pedal position sensor transform the a ccelerator pedal position into output voltage, and emit
the voltage signal to the ECM. Then, the TCM receives accelerator pedal position signal from the ECM via
CAN communication.
A/T CONTROL SYSTEM : Manual Mode SwitchINFOID:0000000006226755
 The manual mode switch [mode select switch and position se lect switch (shift-up/shift-down)] is installed in
the A/T shift selector assembly.
 The mode select switch detects the position (the main shift gate side or manual shift gate side) of the selec-
tor lever and transmits a manual mode signal or a not manual mode signal to the combination meter. Then,
the TCM receives a manual mode signal or non-manual mode signal from the combination meter.
 The position select switch (shift-up) detects that the se lector lever is shifted to the shift-up side of the manual
shift gate and transmits a manual mode shift up signal to the combination meter. Then, the TCM receives a
manual mode shift up signal from the combination meter.
 The position select switch (shift-down) detects that the selector lever is shifted to the shift-down side of the
manual shift gate and transmits a manual mode shift down signal to the combination meter. Then, the TCM
receives a manual mode shift down signal from the combination meter.
Revision: 2010 May2011 QX56

TM-48
< SYSTEM DESCRIPTION >[7AT: RE7R01B]
SYSTEM
LINE PRESSURE CONTROL
LINE PRESSURE CONTROL : System DiagramINFOID:0000000006226771
LINE PRESSURE CONTROL : System DescriptionINFOID:0000000006226772
 When an engine and A/T integrated control signal (engine
torque) equivalent to the engine drive force is
transmitted from the ECM to the TCM, the TC M controls the line pressure solenoid valve.
This line pressure solenoid controls the pressure regul ator valve as the signal pressure and adjusts the pres-
sure of the operating oil discharged from the oil pump to the line pressure most appropriate to the driving
state.
 The TCM has stored in memory a number of patterns fo r the optimum line pressure characteristic for the
driving state.
 In order to obtain the most appropriate line pressure char acteristic to meet the current driving state, the TCM
controls the line pressure solenoid current value and thus controls the line pressure.
Normal Control
Each clutch is adjusted to the necessary pressure to match the
engine drive force.
Back-up Control (Engine Brake)
Malfunction detection conditionTCM electronic substrate temperature
145
°C (293 °F) and 120 seconds
or
150 °C (302 °F)
Control at malfunction Accelerator opening: 0.5/8 or less
Normal return condition  TCM electronic substrate temperature: Less than 140
°C (284 °F)
and
 Vehicle speed: 5 km/h (3 MPH) or less
Vehicle behavior Accelerator opening: output torque of approximately 0.5/8
JSDIA1345GB
PCIA0008E
Revision: 2010 May2011 QX56

SYSTEMTM-51
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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*: This signal is transmitted via communication line.
The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus, the
clutch pressure is adjusted to be appropriate to t he engine load state and vehicle driving state. It becomes
possible to finely control the clutch hydraulic pressu re with high precision and a smoother shift change charac-
teristic is attained.
The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque informa-
tion, etc.
Shift Change System Diagram
*1: Full phase real-time feedback control monitors move ment of gear ratio at gear change, and controls oil
pressure in real-time to achieve the best gear ratio.
BLIPPING CONTROL
This system makes transmission clutch engage readily by controlling (synchronizing) engine revolution
according to the (calculation of) engine revolution after shifting down.
 “BLIPPING CONTROL” functions.
- When downshifting by accelerator pedal depression.
- When downshifting by the manual mode.
PCIA0012E
PCIA0013E
JSDIA0826GB
Revision: 2010 May2011 QX56

SYSTEMTM-53
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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Input/Output Signal Chart
*: This signal is transmitted via communication line.
The TCM activates low brake solenoid valve and controls t he low brake oil pressure to the low pressure level
if the driver does not intend to start the vehicle while the vehicle is being stopped in the “D” position. Therefore,
the low brake is in the release (slip) status and the pow er transmission route of A/T is the same status as the
“N” position. This can decrease the engine load and im proves the fuel economy because the drive force of
engine is not transmitted to the output shaft of A/T.
Idle Neutral Contro l Start Condition
Idle neutral control starts when all of the following c onditions are satisfied. However, the control ends when
any one of the following conditions becomes insufficient during idle neutral control.
NOTE:
The idle neutral control is terminated or prohibited when the TCM and ECM detect that the vehicle is in any of
the conditions as per the following.
 Engine cooling water temperature and A/T fluid temperature are below or above a prescribed temperature.
 A/T malfunction occurs.
 DTC is detected.
 Fail-safe mode activates.
 Idle neutral control is performed continuously for a certain period of time.
Idle Neutral Contro l Resume Condition
Idle neutral control can be resumed when its start condition is fulfilled after any of the following operations is
performed (unless a malfunction occurs in the vehicle).
 After driving at more than a prescribed speed.
 When idle neutral control start conditions are fulfilled for a certain period of time.
SHIFT PATTERN CONTROL
Item Signal
TCM function Actuator
Each sensor, switch and
control unit ⇒ TCM TCM
⇒ ECM ECM ⇒ TCM
Input speed sensor 1, 2 Input speed
N idle instruction
signal (Standby sig- nal)* N idle instruction
signal (Start signal)* Idle neutral con-
trol Low brake sole-
noid valve
Output speed sensor Output shaft revolution
A/T fluid temperature
sensor
ATF temperature
Transmission range
switch Selector lever position
ECM Engine speed signal*
Accelerator pedal posi-
tion signal*
Throttle position signal*
BCM Stop lamp switch signal*
Turn indicator signal*
ABS actuator electric
unit (control unit) Pressure sensor signal*
Decel G sensor signal*
Combination meter Vehicle speed signal*
Driving location : Level road and gentle slope
Selector lever position : “D” position
Vehicle speed : 0 km/h (0 MPH)
Accelerator pedal opening : 0.0 / 8
Brake pedal : Depress
Engine speed : Idle speed
Snow mode switch : OFF
Turn signal lamp and ha zard warning lamp : OFF
Revision: 2010 May2011 QX56