2006 INFINITI QX56 lock

AT-120
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)
Revision: November 20092006 QX56
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)PFP:31940
DescriptionECS00CFT
This malfunction is detected when the A/T does not shift into 5th gear position or the torque converter clutch
does not lock-up as instructed by the TCM. This is not only caused by electrical malfunction (circuits open or
shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation,
etc.
CONSULT-II Reference ValueECS00CFU
On Board Diagnosis LogicECS00CFV

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P0744 A/T TCC S/V FNCTN ” with CONSULT-II 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 CauseECS00CFW

Harness or connectors
(The solenoid circuit is open or shorted.)

Torque converter clutch solenoid valve

Hydraulic control circuit
DTC Confirmation ProcedureECS00CFX
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-II
1. Start engine and Select “TCC S/V FNCTN CHECK” of “DTC
WORK SUPPORT ” mode for “A/T” with CONSULT-II 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 AT- 3 2 4 , "Vehicle Speed When Performing and Releasing Complete
Lock-up" .
–If “TESTING” does not appear on CONSULT-II 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 displayed. (If “NG” is displayed, refer to “DIAGNOSTIC PROCEDURE ”.)
Refer to AT- 1 2 1 , "
Diagnostic Procedure" .
Refer to shift schedule, AT- 3 2 4 , "
Vehicle Speed When Performing and Releasing Complete Lock-up" .
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
BCIA0030E

DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)AT-121
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Revision: November 2009 2006 QX56
WITH GST
Follow the procedure “With CONSULT-II”.
Diagnostic ProcedureECS00CFY
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Turn ignition switch “ON”.
2. Select “MAIN SIGNALS” in “DATA MONITOR ” mode for “A/T”
with CONSULT-II.
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 AT- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
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 connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "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 AT- 1 2 0 , "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
SCIA4793E

AT-134
DTC P1730 A/T INTERLOCK
Revision: November 20092006 QX56
DTC P1730 A/T INTERLOCKPFP:00000
DescriptionECS00CH5

Fail-safe function to detect interlock conditions.
On Board Diagnosis LogicECS00CH6

This is an OBD-II self-diagnostic item.

Diagnostic trouble code “P1730 A/T INTERLOCK ” with CONSULT-II is detected when TCM does not
receive the proper voltage signal from the sensor and switch.

TCM monitors and compares gear position and conditions of each ATF pressure switch when gear is
steady.
Possible CauseECS00CH7

Harness or connectors
(The solenoid and switch circuit is open or shorted.)

Low coast brake solenoid valve

ATF pressure switch 2
DTC Confirmation ProcedureECS00CH8
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-II
1. Turn ignition switch “ ON”. (Do not start engine.)
2. Select “DATA MONITOR ” mode for “A/T” with CONSULT-II.
3. Start engine.
4. Drive vehicle and maintain the following conditions for at least 2 consecutive seconds.
Selector lever: “D” position
5. If DTC is detected, go to AT- 1 3 5 , "
Diagnostic Procedure" .
WITH GST
Follow the procedure “With CONSULT-II”.
BCIA0030E

DTC P1730 A/T INTERLOCKAT-135
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Revision: November 2009 2006 QX56
Judgement of A/T InterlockECS00CH9
When A/T Interlock is judged to be malfunctioning, the vehicle should be fixed in 2nd gear, and should be set
in a condition in which it can travel.
When one of the following fastening patterns is detected, the fail-safe function in correspondence with the indi-
vidual pattern should be performed.
A/T INTERLOCK COUPLING PATTERN TABLE

: NG, X: OK
Diagnostic ProcedureECS00CHA
1. SELF-DIAGNOSIS
With CONSULT-II
1. Drive vehicle.
2. Stop vehicle and turn ignition switch “OFF”.
3. Turn ignition switch “ON”.
4. Select “SELF-DIAG RESULTS” mode for “A/T ” with CONSULT-
II.
OK or NG
OK >> GO TO 2.
NG >> Check low coast brake solenoid valve circuit and func- tion. Refer to AT- 1 5 5 , "
DTC P1772 LOW COAST
BRAKE SOLENOID VALVE" , AT- 1 5 7 , "DTC P1774
LOW COAST BRAKE SOLENOID VALVE FUNCTION" .
2. CHECK DTC
Perform “DTC Confirmation Procedure ”.

Refer to AT- 1 3 4 , "DTC Confirmation Procedure" .
OK or NG
OK >> INSPECTION END
NG >> GO TO 3.
3. CHECK TCM POWER SUPPLY AND GROUND CIRCUIT
Check TCM power supply and ground circuit. Refer to AT- 1 6 7 , "
MAIN POWER SUPPLY AND GROUND CIR-
CUIT" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
Gear position ATF pressure switch output
Fail-safe function Clutch pressure output pattern after fail-safe func-
tion
SW3 (I/C) SW6
(HLR/ C) SW5
(D/C) SW1
(FR/B) SW2
(LC/B) I/C HLR/C D/C FR/B LC/B L/U
A/T interlock
coupling pat-
tern 3rd
–XX –
Held in
2nd gear OFF OFF ON OFF OFF OFF
4th –XX –
Held in
2nd gear OFF OFF ON OFF OFF OFF
5th X X –X
Held in
2nd gear OFF OFF ON OFF OFF OFF
BCIA0031E

AT-136
DTC P1730 A/T INTERLOCK
Revision: November 20092006 QX56
4. DETECT MALFUNCTIONING ITEM
Check the following items:

The A/T assembly harness connector pin terminals for damage or loose connection with harness connec-
tor.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT- 2 3 0 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.

MAIN POWER SUPPLY AND GROUND CIRCUITAT-169
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Revision: November 2009 2006 QX56
3. DETECT MALFUNCTIONING ITEM
Check the following items:

Harness for short or open between battery and A/T assembly harness connector terminals 1, 2

Harness for short or open between ignition switch and A/T assembly harness connector terminal 6

10A fuse [No. 3, located in the fuse block (J/B)] and 10A fuse (No. 49, located in the IPDM E/R)

Ignition switch, Refer to PG-4, "POWER SUPPLY ROUTING CIRCUIT" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
4. CHECK TCM GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/T assembly harness connector.
3. Check continuity between A/T assembly harness connector F9 terminals 5, 10 and ground.
If OK, check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5. DETECT MALFUNCTIONING ITEM
Check the following items:

The A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> GO TO 6.
NG >> Repair or replace damaged parts.
6. PERFORM SELF-DIAGNOSIS
Perform self-diagnosis. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
OK or NG
OK >> INSPECTION END
NG-1 >> Self-diagnosis does not activate: GO TO 7.
NG-2 >> DTC is displayed: Check the malfunctioning system. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC
RESULT MODE" .
Continuity should exist.
SCIA2106E

TROUBLE DIAGNOSIS FOR SYMPTOMSAT-203
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Revision: November 2009 2006 QX56
10. PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to AT- 8 3 , "
TCM Input/Output Signal Reference Val-
ues" .
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 AT- 6 1 ,
"Symptom Chart" (Symptom No.13).
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
A/T Does Not Perform Lock-upECS00CKF
SYMPTOM:
A/T does not perform lock-up at the specified speed.
DIAGNOSTIC PROCEDURE
1. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate torque converter clutch solenoid valve, engine speed signal, turbine rev-
olution sensor, accelerator pedal position sensor, CAN communication?
YES >> Check the malfunctioning system. Refer to AT- 11 8 , "DTC P0740 TORQUE CONVERTER
CLUTCH SOLENOID VALVE" , AT- 11 6 , "DTC P0725 ENGINE SPEED SIGNAL" , AT- 1 0 9 , "DTC
P0717 TURBINE REVOLUTION SENSOR" , AT- 1 2 4 , "DTC P1705 THROTTLE POSITION SEN-
SOR" , AT- 9 6 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT- 1 2 , "
Checking Automatic Trans-
mission Fluid (ATF)" .
OK or NG
OK >> GO TO 3.
NG >> Refill ATF.
SAT638A

TROUBLE DIAGNOSIS FOR SYMPTOMSAT-205
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Revision: November 2009 2006 QX56
7. DETECT MALFUNCTIONING ITEM

Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT- 6 1 ,
"Symptom Chart" (Symptom No.24).
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
8. CHECK SYMPTOM
Check again. Refer to AT- 5 6 , "
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 AT- 8 3 , "
TCM Input/Output Signal Reference Val-
ues" .
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 AT- 6 1 ,
"Symptom Chart" (Symptom No.24).
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
A/T Does Not Hold Lock-up ConditionECS00CKG
SYMPTOM:
The lock-up condition cannot be maintained for more than 30 seconds.
DIAGNOSTIC PROCEDURE
1. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 8 6 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate torque converter clutch solenoid valve, engine speed signal, turbine rev-
olution sensor, CAN communication?
YES >> Check the malfunctioning system. Refer to AT- 11 8 , "DTC P0740 TORQUE CONVERTER
CLUTCH SOLENOID VALVE" , AT- 11 6 , "DTC P0725 ENGINE SPEED SIGNAL" , AT- 1 0 9 , "DTC
P0717 TURBINE REVOLUTION SENSOR" , AT- 9 6 , "DTC U1000 CAN COMMUNICATION LINE"
.
NO >> GO TO 2.