2009 INFINITI QX56 oil

A/T CONTROL SYSTEMTM-23
< FUNCTION DIAGNOSIS >
CEF
G H
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TM
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 This line pressure solenoid controls the pressure regulat or 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.
LINE PRESSURE CONTROL IS BASED ON TH E TCM LINE PRESSURE CHARACTERISTIC PAT-
TERN
 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)
When the select operation is performed during driving and the trans-
mission is shifted down, the line pressure is set according to the
vehicle speed.
During Shift Change
PCIA0007E
PCIA0008E
PCIA0009E
Revision: December 20092009 QX56

TM-24
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
The necessary and adequate line pressure for shift change is set.
For this reason, line pressure pattern setting corresponds to input
torque and gearshift selection. Also, line pressure characteristic is
set according 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 ControlINFOID:0000000003771812
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 the 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.
SHIFT CHANGE
The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque informa-
tion, etc.
Shift Change System Diagram
PCIA0010E
PCIA0011E
PCIA0012E
Revision: December 20092009 QX56

A/T CONTROL SYSTEMTM-25
< FUNCTION DIAGNOSIS >
CEF
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*1: Full phase real-time feedback control monitors move ment of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.
Lock-up ControlINFOID:0000000003771813
The torque converter clutch piston in the torque conv erter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
The torque converter clutch control valve operation is c ontrolled by the torque converter clutch solenoid valve,
which is controlled by a signal from TCM, and the to rque 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
 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.
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 and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
PCIA0013E
Select lever D position 4 position 3 position 2 position
Gear position 54432
Lock-up ×– ×××
Slip lock-up ××–––
PCIA0014E
Revision: December 20092009 QX56

TM-26
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
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 th is 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 converte r 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 pi ston operating pressure is increased and the coupling 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 tor que fluctuation and lock-up operates from low speed.
This raises the fuel efficiency for 4GR and 5GR at both low speed and when the accelerator has a low
degree of opening.
Engine Brake ControlINFOID:0000000003771814
 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 contro ls the low coast brake coupling force.
Control ValveINFOID:0000000003771815
FUNCTION OF CONTROL VALVE
SCIA1520E
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 regu lator valve
Pressure regulator plug
Pressure regu lator 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 1GR, 2GR, 3GR, and 5GR, 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.
Revision: December 20092009 QX56

A/T CONTROL SYSTEMTM-27
< FUNCTION DIAGNOSIS >
CEF
G H
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TM
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FUNCTION OF PRESSURE SWITCH
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 4GR 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 1GR, 3GR, 4GR and 5GR, adjusts the clutch pressure.)
Input clutch control valve When the input clutch is coupled, adjusts the line pressure to the optimum pressure (in-
put clutch pressure) and supplies it to the input clutch. (In 4GR and 5GR, adjusts the
clutch pressure.)
Direct clutch control valve When the direct clutch is coupled, adjusts the line pressure to the optimum pressure (di-
rect clutch pressure) and supplies it to the direct clutch. (In 2GR, 3GR, and 4GR, 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
Name Function
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.
Revision: December 20092009 QX56

TM-68
< COMPONENT DIAGNOSIS >
P0745 PRESSURE CONTROL SOLENOID A
P0745 PRESSURE CONTROL SOLENOID A
DescriptionINFOID:0000000003771902
The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in
response to a signal sent from the TCM.
The line pressure duty cycle value is not consistent when the closed throttle position signal is “ON”.
To confirm the line pressure duty cycle at low pressu re, the accelerator (throttle) should be open until
the closed throttle posi tion signal is “OFF”.
CONSULT-III Reference Value in Data Monitor ModeINFOID:0000000003771903
On Board Diagnosis LogicINFOID:0000000003771904
 This is an OBD-II self-diagnostic item.
 Diagnostic trouble code “P0745” with CONSULT-III is detected under the following conditions.
- When TCM detects an improper voltage drop when it tries to operate the solenoid valve.
- When TCM detects as irregular by comparing target value with monitor value.
Possible CauseINFOID:0000000003771905
 Harness or connectors
(The solenoid circuit is open or shorted.)
 Line pressure solenoid valve
DTC Confirmation ProcedureINFOID:0000000003771906
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following proc edure to confirm the malfunction is eliminated.
WITH CONSULT-III
1. Turn ignition switch “ON” and select “DATA MONITOR” mode for “ENGINE” with CONSULT-III.
2. Engine start and wait at least 5 second.
3. If DTC is detected, go to TM-68, "Diagnosis Procedure"
.
WITH GST
Follow the procedure “With CONSULT-III”.
Diagnosis ProcedureINFOID:0000000003771907
1.CHECK INPUT SIGNAL
With CONSULT-III
1. Turn ignition switch “ON”.
2. Select “MAIN SIGNALS” in “DATA MONITO R” mode for “TRANSMISSION” with CONSULT-III.
3. Start the engine.
4. Read out the value of “LINE PRES SOL” while driving.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Item name Condition Display value (Approx.)
LINE PRES SOL During driving 0.2 - 0.6 A
Item name Condition Display value (Approx.)
LINE PRES SOL During driving 0.2 - 0.6 A
Revision: December 20092009 QX56

TM-120
< SYMPTOM DIAGNOSIS >
SYSTEM SYMPTOM
Check the starting system. Refer to STR-5, "Work Flow".
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
In "P" Position, Vehi cle Moves When PushedINFOID:0000000003771993
SYMPTOM:
Even though the selector lever is set in the “P ” position, the parking mechanism is not actuated,
allowing the vehicle to be moved when it is pushed.
DIAGNOSTIC PROCEDURE
1.CHECK TRANSMISSION RANGE SWITCH CIRCUIT
Perform self-diagnosis. Refer to TM-32, "CONSULT-III Function (TRANSMISSION)"
.
Do the self-diagnosis results indicate transmission range switch?
YES >> Check the malfunctioning system. Refer to TM-44, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK CONTROL CABLE
Check the control cable.
 Refer to TM-195, "Checking of A/T Position"
.
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to TM-195, "Adjustment of A/
T Position".
3.CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to TM-201, "Oil Pan"
.
2. Check A/T fluid condition. Refer to TM-179, "Checking the A/T
Fluid (ATF)".
OK or NG
OK >> INSPECTION END
NG >> GO TO 4.
4.DETECT MALFUNCTIONING ITEM
 Check the malfunction items. If any items are dam aged, repair or replace damaged parts. Refer to TM-152,
"Symptom Table" (Symptom No. 58).
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
In "N" Position, Vehicle MovesINFOID:0000000003771994
SYMPTOM:
Vehicle moves forward or backwar d when selecting “N” position.
DIAGNOSTIC PROCEDURE
LCIA0345E
SCIA5199E
Revision: December 20092009 QX56

SYSTEM SYMPTOMTM-121
< SYMPTOM DIAGNOSIS >
CEF
G H
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K L
M A
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TM
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1.CHECK TRANSMISSION RANGE SWITCH CIRCUIT
Perform self-diagnosis. Refer to TM-32, "CONSULT-III Function (TRANSMISSION)"
.
Do the self-diagnostic results indicate transmission range switch?
YES >> Check the malfunctioning system. Refer to TM-44, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK CONTROL CABLE
Check the control cable.
 Refer to TM-195, "Checking of A/T Position"
.
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to TM-195, "Adjustment of A/
T Position".
3.CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to TM-179, "Checking the A/T Fluid
(ATF)".
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4.CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to TM-201, "Oil Pan"
.
2. Check A/T fluid condition. Refer to TM-179, "Checking the A/T
Fluid (ATF)".
OK or NG
OK >> GO TO 5.
NG >> Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to TM-152,
"Symptom Table" (Symptom No. 60).
5.CHECK SYMPTOM
Check again. Refer to TM-5, "Work Flow"
.
OK or NG
OK >> INSPECTION END
NG >> GO TO 6.
6.PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to TM-104, "Reference Value"
.
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness
connector.
OK or NG
LCIA0345E
SAT638A
SCIA5199E
Revision: December 20092009 QX56