2004 INFINITI QX56 engine

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-213
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MA
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AT
Revision: August 20072004 QX56
A/T Does Not Shift: D4 → D5UCS002IT
SYMPTOM:

The vehicle does not shift-up from the D4 to D5 gear at the specified speed.

The vehicle does not shift-up from the D4 to D5 gear unless A/T is warmed up.
DIAGNOSTIC PROCEDURE
1. CONFIRM THE SYMPTOM
Check if vehicle creeps forward in “D” position and vehicle can be started from D
1.
OK or NG
OK >> GO TO 2.
NG >> Refer to AT- 2 0 1 , "
Vehicle Does Not Creep Forward In “D” Position" , AT-203, "Vehicle Cannot Be
Started From D1" .
2. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate ATF pressure switch 1, ATF pressure switch 5, front brake solenoid
valve, direct clutch solenoid valve, accelerator pedal position sensor, turbine revolution sensor, vehicle speed
sensor A/T (revolution sensor) and vehicle speed sensor MTR?
YES >> Check the malfunctioning system. Refer to AT- 1 7 5 , "DTC P1841 ATF PRESSURE SWITCH 1" ,
AT-181, "
DTC P1845 ATF PRESSURE SWITCH 5" , AT-151, "DTC P1757 FRONT BRAKE
SOLENOID VALVE" , AT-157, "DTC P1762 DIRECT CLUTCH SOLENOID VALVE" , AT-129,
"DTC P1705 THROTTLE POSITION SENSOR" , AT-134, "DTC P1716 TURBINE REVOLUTION
SENSOR" , AT - 11 2 , "DTC P0720 VEHICLE SPEED SENSOR A/T (REVOLUTION SENSOR)" ,
AT-136, "
DTC P1721 VEHICLE SPEED SENSOR MTR" .
NO >> GO TO 3.
3. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT- 1 3 , "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT-59, "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 7.
NG - 1 >> Line pressure high. GO TO 5.
NG - 2 >> Line pressure low. GO TO 6.
SAT6 3 8A
SAT4 9 4G

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-215
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Revision: August 20072004 QX56
10. PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to AT-90, "
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-68,
"Symptom Chart" (Symptom No.13).
OK or NG
OK >> GO TO 9.
NG >> Repair or replace damaged parts.
A/T Does Not Perform Lock-upUCS002IU
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- 9 3 , "
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-115, "DTC P0725 ENGINE SPEED SIGNAL" , AT- 1 3 4 , "DTC
P1716 TURBINE REVOLUTION SENSOR" , AT- 1 2 9 , "DTC P1705 THROTTLE POSITION SEN-
SOR" , AT-103, "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT- 1 3 , "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 3.
NG >> Refill ATF.
SAT6 3 8A

AT-216
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: August 20072004 QX56
3. CHECK LINE PRESSURE
Check line pressure at the engine stall point. Refer to AT- 5 9 , "
LINE
PRESSURE TEST" .
OK or NG
OK >> GO TO 6.
NG - 1 >> Line pressure high. GO TO 4.
NG - 2 >> Line pressure low. GO TO 5.
4. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 4 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-273, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-290, "Oil Pump" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
5. DETECT MALFUNCTIONING ITEM
1. Check control valve with TCM. Refer to AT- 2 4 1 , "
Control Valve With TCM and A/T Fluid Temperature Sen-
sor 2" .
2. Disassemble A/T. Refer to AT-273, "
Disassembly" .
3. Check the following items:
–Oil pump assembly. Refer to AT-290, "Oil Pump" .
–Power train system. Refer to AT-273, "Disassembly" .
–Transmission case. Refer to AT-273, "Disassembly" .
OK or NG
OK >> GO TO 7.
NG >> Repair or replace damaged parts.
6. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-241, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 5 8 , "
Fluid Condition
Check" .
OK or NG
OK >> GO TO 7.
NG >> GO TO 10.
SAT4 9 4G
SCIA5199E

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-217
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AT
Revision: August 20072004 QX56
7. DETECT MALFUNCTIONING ITEM

Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT-68,
"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- 6 3 , "
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-90, "
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-68,
"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 ConditionUCS002IV
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- 9 3 , "
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-115, "DTC P0725 ENGINE SPEED SIGNAL" , AT- 1 3 4 , "DTC
P1716 TURBINE REVOLUTION SENSOR" , AT-103, "DTC U1000 CAN COMMUNICATION
LINE" .
NO >> GO TO 2.

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-219
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Revision: August 20072004 QX56
7. DETECT MALFUNCTIONING ITEM

Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT-68,
"Symptom Chart" (Symptom No.25).
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
Lock-up Is Not ReleasedUCS002IW
SYMPTOM:
The lock-up condition cannot be cancelled even after releasing the accelerator pedal.
DIAGNOSTIC PROCEDURE
1. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 9 3 , "
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-115, "DTC P0725 ENGINE SPEED SIGNAL" , AT- 1 3 4 , "DTC
P1716 TURBINE REVOLUTION SENSOR" , AT-103, "DTC U1000 CAN COMMUNICATION
LINE" .
NO >> GO TO 2.
2. CHECK SYMPTOM
Check again. Refer to AT- 6 3 , "
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 AT-90, "
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.

AT-220
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: August 20072004 QX56
Engine Speed Does Not Return to IdleUCS002IX
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 AT-13, "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 2.
NG >> Refill ATF.
2. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate front brake solenoid valve, direct clutch solenoid valve, ATF pressure
switch 1, ATF pressure switch 5, accelerator pedal position sensor, vehicle speed sensor A/T (revolution sen-
sor) and vehicle speed sensor MTR?
YES >> Check the malfunctioning system. Refer to AT-151, "DTC P1757 FRONT BRAKE SOLENOID
VA LV E" , AT-157, "DTC P1762 DIRECT CLUTCH SOLENOID VALVE" , AT- 1 7 5 , "DTC P1841
ATF PRESSURE SWITCH 1" , AT-181, "DTC P1845 ATF PRESSURE SWITCH 5" , AT-129,
"DTC P1705 THROTTLE POSITION SENSOR" , AT- 11 2 , "DTC P0720 VEHICLE SPEED SEN-
SOR A/T (REVOLUTION SENSOR)" , AT-136, "DTC P1721 VEHICLE SPEED SENSOR MTR" .
NO >> GO TO 3.
3. CHECK A/T FLUID CONDITION
1. Remove oil pan. Refer to AT-241, "
Control Valve With TCM and A/T Fluid Temperature Sensor 2" .
2. Check A/T fluid condition. Refer to AT- 5 8 , "
Fluid Condition
Check" .
OK or NG
OK >> GO TO 4.
NG >> GO TO 7.
4. DETECT MALFUNCTIONING ITEM

Check the malfunction items. If any items are damaged, repair or replace damaged parts. Refer to AT-68,
"Symptom Chart" (Symptom No.65).
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
SAT6 3 8A
SCIA5199E

AT-222
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: August 20072004 QX56
2. CHECK 4TH POSITION SWITCH CIRCUIT
With CONSULT-II
1. Turn ignition switch “ON”.
2. Select "ECU INPUT SIGNALS" in "DATA MONITOR" mode for
"A/T" with CONSULT-II.
3. Read out "OD CONT SW" switch moving selector lever to each
position.
Without CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine)
2. Check voltage between A/T device harness connector terminal
and ground.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3. CHECK A/T FLUID LEVEL
Check the A/T fluid level again. Refer to AT- 1 3 , "
Checking A/T Fluid"
.
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
Monitor item Condition Display value
OD CONT SWWhen setting the selector
lever to "4" and "3" posi-
tion.ON
When setting selector
lever to other positions.OFF
LCIA0339E
Item Connector No.Te r m i n a l N o .
(Wire color)ConditionData
(Approx.)
4th position
switchM2031 (SB) -
GroundWhen setting
the selector
lever to "4"
and "3" posi-
tion.0V
When setting
selector lever
to other posi-
tions.Battery volt-
age
LCIA0340E
SAT6 3 8A

AT-228
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: August 20072004 QX56
2. CHECK 1ST POSITION SWITCH CIRCUIT
With CONSULT-II
1. Turn ignition switch “ON”.
2. Select "ECU INPUT SIGNALS" in "DATA MONITOR" mode for
"A/T" with CONSULT-II.
3. Read out "1 POSITION SW" switch moving selector lever to
each position.
Without CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine)
2. Check voltage between A/T device harness connector terminal
and ground.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3. CHECK A/T FLUID LEVEL
Check the A/T fluid level again. Refer to AT- 1 3 , "
Checking A/T Fluid"
.
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
Monitor item Condition Display value
1 POSITION SWWhen setting the selector
lever to "1" position.ON
When setting selector
lever to other positions.OFF
LCIA0339E
Item Connector No.Te r m i n a l N o .
(Wire color)ConditionData
(Approx.)
1st position
switchM2037 (Y/G) -
GroundWhen setting
the selector
lever to "1"
position.0V
When setting
selector lever
to other posi-
tions.Battery volt-
age
LCIA0341E
SAT6 3 8A