INFINITI QX56 2011 Factory Service Manual

STRUCTURE AND OPERATIONTM-43
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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 When A/T fluid temperature rises [to approximately 100 °C
(212 °F)], bypass valve closes and allows ATF to flow into cooler
core. ATF flowing into cooler core is cooled by air stream caused
by vehicle travel and returned to transmission.
JSDIA1816GB
Revision: 2010 May2011 QX56

TM-44
< SYSTEM DESCRIPTION >[7AT: RE7R01B]
SYSTEM
SYSTEM
A/T CONTROL SYSTEM
A/T CONTROL SYSTEM : System DiagramINFOID:0000000006226767
A/T CONTROL SYSTEM : System DescriptionINFOID:0000000006226768
INPUT/OUTPUT SIGNAL CHART
SYSTEM DESCRIPTION
 The A/T senses vehicle operating conditions through vari
ous sensors or signals. It always controls the opti-
mum shift position and reduces shifting and lock-up shocks.
 Receive input signals transmitted from various switches and sensors.
 Determine required line pressure, shifting point, lock-up operation, etc.
JSDIA1853GB
Sensor (or signal)
⇒TCM function
⇒Actuator
Transmission range switch
Accelerator pedal position signal
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Output speed sensor
Vehicle speed signal
Manual mode switch signal
Stop lamp switch signal
Input speed sensor 1, 2
Yaw rate/side/decel G sensor
Tow mode switch signal Line pressure control (
TM-48
)
Shift change control ( TM-50
)
Shift pattern control ( TM-54
)
Lock-up control ( TM-56
)
Fail-safe control ( TM-45
)
Self-diagnosis ( TM-61
)
CONSULT-III communication line ( TM-61
)
CAN communication line ( TM-103
)Input clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch solenoid valve
Low brake solenoid valve
Torque converter clutch solenoid valve
Line pressure solenoid valve
Anti-interlock solenoid valve
2346 brake solenoid valve
A/T CHECK indicator lamp
Tow mode indicator lamp
Shift position indicator
Back-up lamp relay
Starter relay
Revision: 2010 May2011 QX56

SYSTEMTM-45
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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 Transmit required output signals to the respective solenoids.
A/T CONTROL SYSTEM : Fail-SafeINFOID:0000000006226769
TCM has the electrical fail-safe mode. The mode is divi ded into a maximum of 3 phases (1st fail-safe, 2nd fail-
safe and final fail-safe) and functions so that the operat ion can be continued even if the signal circuit of the
main electronically controlled input/output parts is damaged.
Even if the electronic circuit is normal, the fail-safe mode may start under special conditions (such as when the
brake pedal is depressed suddenly from a hard wheel spin st atus to stop the rotation of wheels). In this case,
turn the ignition switch OFF and back to ON after 5 seconds to resume the normal shift pattern.
Consequently, the customer's vehicle may already return to the normal condition. Refer to TM-88, "
Diagnosis
Flow".
FAIL-SAFE FUNCTION
1st Fail-SafeThe mode that the vehicle can stop safely, to prompt the driver to stop if the malfunction occurs and to shift to
2nd fail-safe early. It shifts to 2nd fail-safe or final fail-safe after the vehicle stopped.
2nd Fail-Safe The mode that the vehicle shifts to final fail-safe without changing the behavior, by identifying the malfunction-
ing parts in the condition that the driving force required for the driving is secured.
Final Fail-Safe  Selects the shifting pattern that the malfunctioning parts identified at 1st fail-safe and 2nd fail-safe are not
used, and then secure the driving force that is required for the driving.
 The mode that the shifting performance does not decrease by normal shift control.
DTC Veh ic le
condition Vehicle behavior for 1st fail-safe Vehicle behavior for 2nd fail-safe Vehicle behavior for final fail-safe
P0615 — Starter is disabled — Starter is disabled
P0705 —  Fixed in the “D” position (The
shifting can be performed)
 30 km/h (19MPH) or less
 Lock-up is prohibited
 The shifting between the gears of 3 - 4 - 5 - 6 - 7 can be per-
formed
 Manual mode is prohibited
 Shift position indicator is switched OFF
 Starter relay is switched OFF (starter is disabled)
 Back-up lamp is OFF
 Large shift shock — Fixed in the “D” position (The
shifting can be performed)
 30 km/h (19 MPH) or less
 Lock-up is prohibited
 The shifting between the gears of 3 - 4 - 5 - 6 - 7 can be per-
formed
 Manual mode is prohibited
 Shift position indicator is switched OFF
 Starter relay is switched OFF (starter is disabled)
 Back-up lamp is OFF
 Large shift shock
P0710 Between
the gears of 1 - 2 - 3  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited —
 The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited
Between
the gears of 4 - 5 - 6 - 7  Fix the gear while driving
 Manual mode is prohibited
—
P0717 Between
the gears of
1 - 2 - 3  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited —
 The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited
Between
the gears of 4 - 5 - 6 - 7  Fix the gear while driving
 Manual mode is prohibited
—
Revision: 2010 May2011 QX56

TM-46
< SYSTEM DESCRIPTION >[7AT: RE7R01B]
SYSTEM
P0720Between
the gears of 1 - 2 - 3  Only downshift can be per-
formed
 Manual mode is prohibited
 A vehicle speed signal from the combination mete r is regarded
as an effective signal —
 The shifting between the gears of 1 - 2 - 3 can be performed
 Manual mode is prohibited
Between
the gears of 4 - 5 - 6 - 7  Fix the gear at driving
 Manual mode is prohibited
 A vehicle speed signal from the
combination mete r is regarded
as an effective signal —
P0729
P0731
P0732
P0733
P0734
P0735
P1734 Neutral
malfunction
between
the gears of
1 - 2 - 3 and
7
Locks in 4GR
 Manual mode is prohibited
Neutral
— Locks in 1GR
 The shifting between the gears
of 1 - 2 can be performed
 The shifting between the gears
of 1 - 2 - 3 can be performed
 The shifting between the gears of 4 - 5 - 6 can be performed
 Manual mode is prohibited
Other than
the above  Driving with the gear ratio be-
tween 1GR and 2GR
 Driving with the gear ratio be-
tween 2GR and 3GR
Locks in 3GR
Locks in 4GR
 Fix the gear while driving
 Manual mode is prohibited
Neutral  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited  Locks in 1GR
 The shifting between the gears
of 1 - 2 can be performed
 The shifting between the gears of 1 - 2 - 3 can be performed
 The shifting between the gears
of 2 - 3 - 4 can be performed
 The shifting between the gears of 3 - 4 can be performed
 The shifting between the gears of 4 - 5 - 6 can be performed
 Manual mode is prohibited
P0730 —  Manual mode is prohibited
Neutral  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited  Locks in 1GR
 The shifting between the gears
of 1 - 2 can be performed
 The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited
P0740 —  Lock-up is prohibited
 Slip lock-up is prohibited —
 Lock-up is prohibited
 Slip lock-up is prohibited
P0744 —  Lock-up is prohibited
 Slip lock-up is prohibited — Lock-up is prohibited
 Slip lock-up is prohibited
P0750
P0775
P0795
P2713
P2722
P2731
P2807 —
 Locks in 2GR, 3GR, 4GR, 5GR,
6GR or 7GR
 Manual mode is prohibited — Locks in 1GR
 The shifting between the gears
of 1 - 2 - 3 can be performed
 The shifting between the gears
of 3 - 4 - 5 can be performed
 The shifting between the gears of 4 - 5 - 6 can be performed
 The shifting between the gears of 1 - 2 - 3 - 4 - 5 - 6 can be per-
formed
 Manual mode is prohibited
P0780 —  Manual mode is prohibited
Neutral
— The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited
P1705 —  Downshift when accelerator ped-
al is depressed is prohibited
 Upshift when accelerator pedal is released is prohibited
 Manual mode is prohibited  Downshift when accelerator ped-
al is depressed is prohibited
 Upshift when accelerator pedal is released is prohibited
 Manual mode is prohibited  Downshift when accelerator ped-
al is depressed is prohibited
 Upshift when accelerator pedal is released is prohibited
 Manual mode is prohibited
DTC
Vehicle
condition Vehicle behavior for 1st fail-safe Vehicle behavior for 2nd fail-safe Vehicle behavior for final fail-safe
Revision: 2010 May2011 QX56

SYSTEMTM-47
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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A/T CONTROL SYSTEM : Protection ControlINFOID:0000000006226770
The TCM becomes the protection control status temporar ily to protect the safety when the safety of TCM and
transmission is lost. It automatically returns to the normal status if the safety is secured.
The TCM has the following protection control.
REVERSE INHIBIT CONTROL
Intercepts the torque transmission and shift to the neutral stat us if the selector lever is shifted to “R” position
while the vehicle moves forward at the vehicle speed 10 km/h (7 MPH) or more.
1ST ENGINE BRAKE PROTECTION CONTROL
Controls the engine brake so as not to make effective by turning the front brake solenoid output to OFF when
each solenoid becomes the electricity pattern of 1st engine brake during driving at the vehicle speed 25 km/h
or more in any positions other than “R” position and 1GR.
TCM HIGH TEMPERATURE PROTECTION CONTROL
Limit the accelerator opening and forcibly control the vehi cle to the low torque driving when the electronic sub-
strate in TCM reaches the high temperature.
P1730 —  Neutral
 Manual mode is prohibited  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited Locks in 1GR
 The shifting between the gears
of 2 - 3 - 4 can be performed
 The shifting between the gears
of 3 - 4 can be performed
 The shifting between the gears of 4 - 5 - 6 can be performed
 Manual mode is prohibited
P1815 — Manual mode is prohibited — Manual mode is prohibited
U0300
U1000 Between
the gears of 1 - 2 - 3  The shifting between the gears
of 1 - 2 - 3 can be performed
 Manual mode is prohibited —
 The shifting between the gears
of 1 - 2 - 3 can be performed
 Line pressure is set to the maxi-
mum hydraulic pressure
 Manual mode is prohibited
Between
the gears of 4 - 5 - 6 - 7  Fix the gear at driving
 Manual mode is prohibited
—
P0720 and
P1721 — Locks in 5GR — Locks in 5GR
DTC
Veh ic le
condition Vehicle behavior for 1st fail-safe Vehicle behavior for 2nd fail-safe Vehicle behavior for final fail-safe
Malfunction detection condition Vehicle speed: 10 km/h (7 MPH) or more
Control at malfunction Neutral
Normal return condition  Vehicle speed: 8 km/h (5 MPH) or less
and
 Engine speed: 2,200 rpm or less
Vehicle behavior  The torque transmission cannot be performed
 There is a shock just before a vehicle stop
Malfunction detection condition Select lever and gear: Any position other than “R” position and 1GR
and
 Vehicle speed: More than 25 km/h (16 MPH)
Control at malfunction Front brake solenoid output signal; OFF
Normal return condition Other than detection condition of malfunction
Vehicle behavior Does not exist
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-49
< SYSTEM DESCRIPTION > [7AT: RE7R01B]
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When the select operation is performed during driving and the A/T is
shifted down, the line pressure is set according to the vehicle speed.
During Shift Change
The necessary and adequate line pressure for shift change is set.
For this reason, line pressure pattern setting corresponds to engine
torque and gearshift selection. Also, line pressure characteristic cor-
responds to engine speed, during engine brake operation.
At Low Fluid Temperature
When the A/T fluid temperature drops below the prescribed tempera-
ture, in order to speed up the action of each friction element, the line
pressure is set higher than the normal line pressure characteristic.
SHIFT CHANGE CONTROL
PCIA0009E
PCIA0010E
PCIA0011E
Revision: 2010 May2011 QX56

TM-50
< SYSTEM DESCRIPTION >[7AT: RE7R01B]
SYSTEM
SHIFT CHANGE CONTROL : System Diagram
INFOID:0000000006226773
SHIFT CHANGE CONTROL : System DescriptionINFOID:0000000006226774
Input/Output Signal Chart
Item Signal TCM function Actuator
Input speed sensor 1, 2 Input speed
Shift change control High and low reverse
clutch solenoid valve
 Direct clutch solenoid
valve
 Input clutch solenoid valve
 Low brake solenoid valve
 2346 brake solenoid valve
 Front brake solenoid valve
 Torque converter clutch so- lenoid valve
 Line pressure solenoid valve
 Anti-interlock solenoid valve
Output speed sensor Vehicle speed
A/T fluid temperature sensor ATF temperature
ECM
Engine speed signal*
Accelerator pedal position signal*
Closed throttle position signal*
Engine and A/T integrated control signal
(Engine torque)*
BCM Stop lamp switch signal*
JSDIA1659GB
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

TM-52
< SYSTEM DESCRIPTION >[7AT: RE7R01B]
SYSTEM
 TCM selects “BLIPPING CONTROL”
or “NORMAL SHIFT CONTROL” according to the gear position, the
selector lever position, the engine torque and the speed when accelerating by pedal depression.
 Engine speed control demand signal is transmitted from TCM to ECM under “BLIPPING CONTROL”.
 ECM synchronizes the engine speed according to the engine speed control demand signal.
Downshifting by accelerator pedal depression
Downshifting by the manual mode
IDLE NEUTRAL CONTROL
JSDIA0815GB
JSDIA0817GB
Revision: 2010 May2011 QX56