torque INFINITI QX56 2008 Factory Service Manual

P0740 TORQUE CONVERTERTM-63
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P0740 TORQUE CONVERTER
DescriptionINFOID:0000000001604075
• The torque converter clutch solenoid valve is activated, with the gear in D4, D5 by the TCM in response to
signals sent from the input speed s ensor and accelerator pedal position s ensor (throttle position sensor).
Torque converter clutch piston operation will then be controlled.
• Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
• When the accelerator pedal is depressed (less than 1/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.
CONSULT-III Reference Val ue in Data Monitor ModeINFOID:0000000001604076
On Board Diagnosis LogicINFOID:0000000001604077
• This is an OBD-II self-diagnostic item.
• Diagnostic trouble code “P0740” 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:0000000001604078
• Torque converter clutch solenoid valve
• Harness or connectors
(The solenoid circuit is open or shorted.)
DTC Confirmation ProcedureINFOID:0000000001604079
CAUTION:
Always drive vehicle at a safe speed.
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 procedure to confirm the malfunction is eliminated.
WITH CONSULT-III
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “DATA MONITOR” mode for “ENGINE” with CONSULT-III.
3. Start engine and maintain the following conditions for at least 5 consecutive seconds. VHCL SPEED SE: 80 km/h (50 MPH) or more
ACCELE POS: 0.5/8 - 1.0/8
SELECTOR LEVER: “D” position
Driving location: Driving the vehic le uphill (increased engine load) will help maintain the driving
conditions required for this test.
4. If DTC is detected go to TM-63, "
Diagnosis Procedure".
WITH GST
Follow the procedure “With CONSULT-III”.
Diagnosis ProcedureINFOID:0000000001604080
1.CHECK INPUT SIGNAL
With CONSULT-III
1. Turn ignition switch “ON”.
2. Select “MAIN SIGNALS” in “DATA MONITOR” mode for “TRANSMISSION” with CONSULT-III.
3. Start engine.
Item name Condition Display value (Approx.)
TCC SOLENOID When performing slip lock-up
0.2 - 0.4 A
When performing lock-up 0.4 - 0.6 A
Revision: March 2010 2008 QX56

TM-64
< COMPONENT DIAGNOSIS >
P0740 TORQUE CONVERTER
4. Read out the value of “TCC SOLENOID” while driving.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to TM-92, "
Diagnosis Procedure".
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3.DETECT MALFUNCTIONING ITEM
Check the following items:
• The A/T assembly harness connector pin terminals for damage or loose connection with harness connector.
OK or NG
OK >> Replace the control valve with TCM. Refer to TM-201, "Control Valve with TCM and A/T Fluid
Temperature Sensor 2".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to TM-63, "
DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value (Approx.)
TCC SOLENOID When performing slip lock-up
0.2 - 0.4 A
When performing lock-up 0.4 - 0.6 A
Revision: March 2010 2008 QX56

P0744 TORQUE CONVERTERTM-65
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P0744 TORQUE CONVERTER
DescriptionINFOID:0000000001604081
This malfunction is detected when the A/T does not lock- up.This is not only caused by electrical malfunction
(circuits open or shorted) but also by mechanical malfunc tion such as control valve sticking, improper solenoid
valve operation, etc.
CONSULT-III Reference Val ue in Data Monitor ModeINFOID:0000000001604082
On Board Diagnosis LogicINFOID:0000000001604083
• This is an OBD-II self-diagnostic item.
• Diagnostic trouble code “P0744” with CONSULT-III is detected under the following conditions.
- When A/T cannot perform lock-up even if electrical circuit is good.
- When TCM detects as irregular by comparing difference value with slip rotation.
Possible CauseINFOID:0000000001604084
• Harness or connectors
(The solenoid circuit is open or shorted.)
• Torque converter clutch solenoid valve
• Hydraulic control circuit
DTC Confirmation ProcedureINFOID:0000000001604085
CAUTION:
Always drive vehicle at a safe speed.
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 procedure to confirm the malfunction is eliminated.
WITH CONSULT-III
1. Start engine and Select “TCC S/V FNCTN CHECK” of “DTC WORK SUPPORT” mode for “TRANSMIS- SION” with CONSULT-III and touch “START”.
2. Accelerate vehicle to more than 80 km/h (50 MPH) and maintain the following condition continuously until “TESTING” has turned to “COMPLETE”. (It will take approximately 30 seconds after “TESTING” shows.)
ACCELE POSI: More than 1.0/8 (at all times during step 4)
TCC SOLENOID: 0.4 - 0.6 A
Selector lever: “D” position
[Reference speed: Constant speed of more than 80 km/h (50 MPH)]
- Make sure “GEAR” shows “5”.
- For shift schedule, refer to TM-291, "
Vehicle Speed at Which Gear Shifting Occurs".
- If “TESTING” does not appear on CONSULT-III for a long time, select “SELF-DIAG RESULTS”. In
case a 1st trip DTC other than P0744 is shown, refer to applicable “TROUBLE DIAGNOSIS FOR
DTC”.
3. Make sure that “OK” is disp layed. (If “NG” is displayed, refer to “DIAGNOSTIC PROCEDURE”.)
Refer to TM-66, "
Diagnosis Procedure".
Refer to shift schedule, TM-291, "
Vehicle Speed at Which Gear Shifting Occurs".
WITH GST
Follow the procedure “With CONSULT-III”.
Item name Condition Display value (Approx.)
TCC SOLENOID When performing slip lock-up
0.2 - 0.4 A
When performing lock-up 0.4 - 0.6 A
Revision: March 2010 2008 QX56

TM-66
< COMPONENT DIAGNOSIS >
P0744 TORQUE CONVERTER
Diagnosis Procedure
INFOID:0000000001604086
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 “TCC SOLENOID” while driving.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to TM-92, "
Diagnosis Procedure".
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3.DETECT MALFUNCTIONING ITEM
Check the following items:
• The A/T assembly harness connector pin terminals for damage or loose connection with harness connector.
OK or NG
OK >> Replace the control valve with TCM. Refer to TM-201, "Control Valve with TCM and A/T Fluid
Temperature Sensor 2".
NG >> Repair or replace damaged parts.
4.CHECK DTC
Perform “DTC Confirmation Procedure”.
• Refer to TM-65, "
DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
Item name Condition Display value (Approx.)
TCC SOLENOID When performing slip lock-up
0.2 - 0.4 A
When performing lock-up 0.4 - 0.6 A
Revision: March 2010 2008 QX56

TCM
TM-115
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Even when the electronic circuits are normal, under s pecial conditions (for example, when slamming on the
brake with the wheels spinning drastically and stopping the tire rotation), the transmission can go into fail-safe
mode. If this happens, switch “OFF” the ignition switch for 10 seconds, then switch it “ON” again to return to
the normal shift pattern. Therefore, the customer's vehicle has returned to normal, so handle according to the
“diagnostics flow” (Refer to TM-5, "
Work Flow").
FAIL-SAFE FUNCTION
If any malfunction occurs in a sensor or solenoid, th is function controls the A/T to mark driving possible.
Output Speed Sensor
• Signals are input from two systems - from output s peed sensor installed on the transmission and from com-
bination meter so normal driving is possible even if t here is a malfunction in one of the systems. And if output
speed sensor has unusual cases, 5GR is prohibited.
Accelerator Pedal Position Sensor
• If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM according
to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow sys-
tems, the engine speed is fixed by ECM to a pre-determined engine speed to make driving possible.
Throttle Position Sensor
• If there is a malfunction in one of the systems, the accelerator opening angle is controlled by ECM according
to a pre-determined accelerator angle to make driving possible. And if there are malfunctions in tow sys-
tems, the accelerator opening angle is controlled by the idle signal sent from the ECM which is based on
input indicating either idle condition or off-idle condition (pre-determined accelerator opening) in order to
make driving possible.
Transmission Range Switch
• In the unlikely event that a malfunction signal enters t he TCM, the position indicator is switched “OFF”, the
starter relay is switched “OFF” (starter starting is disabled), the back-up lamp relay switched “OFF” (back-up
lamp is OFF) and the position is fixed to the “D” range to make driving possible.
Starter Relay
• The starter relay is switched “OFF”. (Starter starting is disabled.)
Interlock
• If there is an interlock judgment malfunction, the tr ansmission is fixed in 2GR to make driving possible.
NOTE:
When the vehicle is driven fixed in 2GR, a inpu t speed sensor malfunction is displayed, but this is
not a input speed sensor malfunction.
• When the interlock is detected at the 3GR or more, it is locked at the 2GR.
1st Engine Braking
• When there is an 1st engine brake judgment malfunction, the low coast brake solenoid is switched “OFF” to
avoid the engine brake operation.
Line Pressure Solenoid
• The solenoid is switched “OFF” and the line pressure is set to the maximum hydraulic pressure to make driv- ing possible.
Torque Converter Clutch Solenoid
• The solenoid is switched “OFF” to release the lock-up.
Low Coast Brake Solenoid
• When a (electrical or functional) malfunction occurs, in order to make driving possible, the engine brake is
not applied in 1GR and 2GR.
Input Clutch Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4th gear to make driving possible.
Direct Clutch Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4GR to make driving possible.
Front Brake Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid “ON”, in order to make driving possible, the
A/T is held in 5GR; if the solenoid is OFF, 4GR.
Revision: March 2010 2008 QX56

TM-116
< ECU DIAGNOSIS >
TCM
High and Low Reverse Clutch Solenoid
• If a (electrical or functional) malfunction occurs with the solenoid either “ON” or “OFF”, the transmission is
held in 4GR to make driving possible.
Input Speed Sensor 1 or 2
• The control is the same as if there were no turbine revolution sensors, 5GR is prohibited.
DTC Inspection Priority ChartINFOID:0000000001604176
If some DTCs are displayed at the same time, perform inspections one by one based on the following priority
chart.
NOTE:
If DTC U1000 is displayed with other DTCs, first perform the trouble diagnosis for DTC U1000. Refer to
TM-38, "
Diagnosis Procedure".
DTC No. IndexINFOID:0000000001604177
NOTE:
If DTC U1000 is displayed with other DTC, first pe rform the trouble diagnosis for DTC U1000. Refer to
TM-38, "
Diagnosis Procedure".
Priority Detected items (DTC)
1 U1000 CAN COMM CIRCUIT
2 Except above
DTC
Items
(CONSULT- III screen terms) Reference page
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only
“TRANSMISSION”
— P0615STARTER RELAY TM-39
P0700P0700TRANSMISSION CONT TM-42
P0705P0705T/M RANGE SWITCH A TM-43
P0710P1710TRANS FLUID TEMP SEN TM-71
P0717P0717INPUT SPEED SENSOR A TM-46
P0720P0720OUTPUT SPEED SENSOR TM-49
—P0725ENGINE SPEED TM-51
P0731P07311GR INCORRECT RATIO TM-54
P0732P07322GR INCORRECT RATIO TM-56
P0733P07333GR INCORRECT RATIO TM-58
P0734P07344GR INCORRECT RATIO TM-60
P0735P07355GR INCORRECT RATO TM-62
P0740P0740TORQUE CONVERTER TM-63
P0744 P0744 TORQUE CONVERTER TM-66
P0745P0745PC SOLENOID A TM-67
—P1705TP SENSOR TM-69
—P1721VEHICLE SPEED SIGNAL TM-74
P1730P1730INTERLOCK TM-76
—P17311GR E/BRAKING TM-78
P1752P1752INPUT CLUTCH SOL TM-80
P1757P1757FR BRAKE SOLENOID TM-82
P1762P1762DRCT CLUTCH SOL TM-84
P1767P1767HLR CLUTCH SOLENOID TM-86
Revision: March 2010 2008 QX56

TCM
TM-117
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*1: These numbers are prescribed by SAE J2012.
*2: These malfunctions cannot be displayed MIL if another malfunction is assigned to MIL.
DTC Alphabetical IndexINFOID:0000000001604178
NOTE:
If DTC U1000 is displayed with other DTC, first pe rform the trouble diagnosis for DTC U1000. Refer to
TM-38, "
Diagnosis Procedure".
*1: These numbers are prescribed by SAE J2012.
*2: These malfunctions cannot be displayed MIL if another malfunction is assigned to MIL. P1772
P1772L C BRAKE SOLENOID TM-88
P1774 (2*) P1774 LC BRAKE SOLENOID TM-90
U1000U1000CAN COMM CIRCUIT TM-38
DTC
Items
(CONSULT- III screen terms) Reference page
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only
“TRANSMISSION”
Items
(CONSULT- III screen terms) DTC
Reference page
OBD- II
Except OBD- II
CONSULT- III GST (*1) CONSULT- III only
“TRANSMISSION”
1GR E/BRAKING —P1731TM-78
1GR INCORRECT RATIO P0731P0731TM-54
2GR INCORRECT RATIO P0732P0732TM-56
3GR INCORRECT RATIO P0733P0733TM-58
4GR INCORRECT RATIO P0734P0734TM-60
5GR INCORRECT RATIO P0735P0735TM-62
INTERLOCK P1730P1730TM-76
TORQUE CONVERTER P0744 P0744 TM-66
TRANS FLUID TEMP SEN P0710P1710TM-71
CAN COMM CIRCUIT U1000U1000TM-38
DRCT CLUTCH SOL P1762P1762 TM-84
ENGINE SPEED —P0725TM-51
FR BRAKE SOLENOID P1757P1757TM-82
HLR CLUTCH SOLENOID P1767P1767TM-86
INPUT CLUTCH SOL P1752P1752TM-80
PC SOLENOID A P0745P0745TM-67
L C BRAKE SOLENOID P1772P1772TM-88
L C BRAKE SOLENOID P1774 P1774 TM-90
T/M RANGE SWITCH A P0705P0705TM-43
STARTER RELAY —P0615TM-39
TORQUE CONVERTER P0740P0740TM-63
TRANSMISSION CONT P0700P0700TM-42
TP SENSOR —P1705TM-69
INPUT SPEED SENSOR A P0717P0717TM-46
VEHICLE SPEED SIGNAL —P1721TM-74
OUTPUT SPEED SENSOR P0720P0720TM-49
Revision: March 2010 2008 QX56

SYSTEM SYMPTOMTM-137
< SYMPTOM DIAGNOSIS >
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NG >> Repair or replace damaged parts.
7.CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to TM-199, "
Oil Pan".
2. Check A/T fluid condition. Refer to TM-178, "
Checking the A/T
Fluid (ATF)".
OK or NG
OK >> GO TO 8.
NG >> GO TO 11.
8.DETECT MALFUNCTIONING ITEM
• Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to TM-151,
"Symptom Table" (Symptom No.13).
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
9.CHECK SYMPTOM
Check again. Refer to TM-190, "
Cruise Test - Part 1".
OK or NG
OK >> INSPECTION END
NG >> GO TO 10.
10.PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to TM-103, "
Reference Value".
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
11 .DETECT MALFUNCTIONING ITEM
• Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to TM-151,
"Symptom Table" (Symptom No.13).
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
A/T Does Not Perform Lock-upINFOID:0000000001604191
SYMPTOM:
A/T does not perform lock-up at the specified speed.
DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnostic results indicate torque converter clutch solenoid valve, engine speed signal, input
speed sensor, accelerator pedal position sensor, CAN communication?
YES >> Check the malfunctioning system. Refer to TM-63, "Diagnosis Procedure", TM-51, "Diagnosis
Procedure", TM-46, "Diagnosis Procedure", EC-382, "Diagnosis Procedure", TM-38, "Diagnosis
Procedure".
SCIA5199E
Revision: March 2010 2008 QX56

SYSTEM SYMPTOMTM-139
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2. Check A/T fluid condition. Refer to TM-178, "Checking the A/T
Fluid (ATF)".
OK or NG
OK >> GO TO 7.
NG >> GO TO 10.
7.DETECT MALFUNCTIONING ITEM
• Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to TM-151,
"Symptom Table" (Symptom No.24).
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
8.CHECK SYMPTOM
Check again. Refer to TM-190, "
Cruise Test - Part 1".
OK or NG
OK >> INSPECTION END
NG >> GO TO 9.
9.PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to TM-103, "
Reference Value".
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
10.DETECT MALFUNCTIONING ITEM
• Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to TM-151,
"Symptom Table" (Symptom No.24).
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
A/T Does Not Hold Lock-up ConditionINFOID:0000000001604192
SYMPTOM:
The lock-up condition cannot be main tained for more than 30 seconds.
DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnostic results indicate torque converter clutch solenoid valve, engine speed signal, input
speed sensor, CAN communication?
YES >> Check the malfunctioning system. Refer to TM-63, "Diagnosis Procedure", TM-51, "Diagnosis
Procedure", TM-46, "Diagnosis Procedure", TM-38, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK A/T FLUID LEVEL
SCIA5199E
Revision: March 2010 2008 QX56

SYSTEM SYMPTOMTM-141
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DIAGNOSTIC PROCEDURE
1.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnostic results indicate torque converter clutch solenoid valve, engine speed signal, input
speed sensor, CAN communication?
YES >> Check the malfunctioning system. Refer to TM-63, "Diagnosis Procedure", TM-51, "Diagnosis
Procedure", TM-46, "Diagnosis Procedure", TM-38, "Diagnosis Procedure".
NO >> GO TO 2.
2.CHECK SYMPTOM
Check again. Refer to TM-190, "
Cruise Test - Part 1".
OK or NG
OK >> INSPECTION END
NG >> GO TO 3.
3.PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to TM-103, "
Reference Value".
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> INSPECTION END
NG >> Repair or replace damaged parts.
Engine Speed Does Not Return to IdleINFOID:0000000001604194
SYMPTOM:
When a shift-down is performed, the engine speed does not smoothly return to the idling speed.
DIAGNOSTIC PROCEDURE
1.CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to TM-178, "
Checking the A/T Fluid
(ATF)".
OK or NG
OK >> GO TO 2.
NG >> Refill ATF.
2.CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to TM-32, "
CONSULT-III Function (TRANSMISSION)".
Do the self-diagnostic results indicate front brake sol enoid valve, direct clutch solenoid valve, accelerator
pedal position sensor, output speed sensor and vehicle speed sensor signal?
YES >> Check the malfunctioning system. Refer to TM-82, "Diagnosis Procedure", TM-84, "Diagnosis
Procedure", EC-382, "Diagnosis Procedure", TM-49, "Diagnosis Procedure", TM-74, "Diagnosis
Procedure".
NO >> GO TO 3.
3.CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to TM-199, "
Oil Pan".
SAT638A
Revision: March 2010 2008 QX56