2009 INFINITI QX56 check engine

DLN-114
< SYMPTOM DIAGNOSIS >[ATX14B]
HEAVY TIGHT-CORNER BRAKING SYMPTOM OCCURS
HEAVY TIGHT-CORNER BR
AKING SYMPTOM OCCURS
DescriptionINFOID:0000000003772176
This symptom occurs when the vehicle is accelerati ng in 4WD and the steering wheel is turned fully either
direction. It may feel like a bump or being pushed fr om behind. A small amount of this bumping feeling is
acceptable under certain road conditions. The transfer case may be adjusted using the CONSULT-III to com-
pensate for this condition.
Diagnosis ProcedureINFOID:0000000003772177
DIAGNOSTIC PROCEDURE
NOTE:
 Light tight-corner braking symptom may occur depending on driving conditions in AUTO mode. This is not a malfunction.
 Heavy tight-corner braking symptom occurs when vehicle is driven in the following conditions: 4WD shift
switch is 4H or 4LO, steering wheel is turned fully to either side.
1.CHECK SYSTEM FOR CAN COMMUNICATION LINE
Perform self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)"
.
Is CAN COMM CIRCUIT [U1000] displayed?
YES >> Perform trouble diagnosis for CAN communication line.
NO >> GO TO 2.
2.CHECK SYSTEM FOR 4WD SHIFT SWITCH
Perform trouble diagnosis for 4WD shift switch system. Refer to DLN-31, "Diagnosis Procedure"
.
Are the inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK ACCELERATOR PEDAL POSITION SIGNAL CIRCUIT
Perform self diagnosis for ECM. Refer to EC-63, "CONSULT-III Function (ENGINE)"
.
Is any malfunction deteced by self-diagnosis?
YES >> Check the malfunctioning system.
NO >> GO TO 4.
4.CHECK SYSTEM FOR CLUT CH PRESSURE SOLENOID
Perform trouble diagnosis for clutch pressure solenoid system. Refer to DLN-70, "Diagnosis Procedure"
.
Are the inspection results normal?
YES >> GO TO 5.
NO >> Repair or replace damaged parts.
5.SYMPTOM CHECK
Check again.
Are the inspection results normal?
YES >> Inspection End.
NO >> GO TO 6.
6.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to DLN-81, "Reference Value"
.
Are the inspection results normal?
YES >> GO TO 7.
NO >> Check transfer control unit pin terminals fo r damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
7.CHECK TRANSFER INNER PARTS
1. Disassemble transfer assembly. Refer to DLN-142, "Disassembly and Assembly"
.
2. Check transfer inner parts.
Revision: December 20092009 QX56

DLN-116
< SYMPTOM DIAGNOSIS >[ATX14B]
ATP SWITCH
ATP SWITCH
DescriptionINFOID:0000000003772178
The ATP indicator is ON when the transfer case is not in neutral.
Diagnosis ProcedureINFOID:0000000003772179
DIAGNOSTIC PROCEDURE
1.CHECK ATP SWITCH SIGNAL

With CONSULT-III
1. Start engine.
2. Select DATA MONITOR mode for A LL MODE AWD/4WD with CONSULT-III.
3. Read out the value of ATP SWITCH.
Without CONSULT-III
1. Start engine.
2. Check voltage between transfer control unit harness connector
terminal and ground.
Are inspection results normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN TRANSFER CONTROL UNIT AND ATP SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness c onnector and the ATP switch harness connector.
3. Check continuity between transfer control unit harness connec- tor E143 terminal 40 and ATP switch harness connector F55 ter-
minal 8.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK GROUND CIRCUIT
Condition Display value
 Vehicle stopped
 Engine running
 A/T selector lever N
 Brake pedal de- pressed 4WD shift switch
: 4H to 4LO or 4LO to 4H
(While actuator motor is operating.)
ON
Except the above OFF
Connector Terminal Condition Voltage
(Approx.)
E143 40 -
Ground  Vehicle stopped
 Engine running
 A/T selector lever
N
 Brake pedal de- pressed 4WD shift switch: 4H
to 4LO or 4LO to 4H
(While actuator motor
is operating.)
0V
Except the above Battery
voltage
SDIA2755E
Continuity should exist.
SDIA2756E
Revision: December 20092009 QX56

ATP SWITCHDLN-117
< SYMPTOM DIAGNOSIS > [ATX14B]
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1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect ATP switch harness connector.
3. Check continuity between ATP switch harness connector F55 terminal 9 and ground.
Also check harness for short to ground and short to power.
Are inspection results normal?
YES >> GO TO 4.
NO >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK ATP SWITCH
1. Turn ignition switch OFF. (Stay for at least 5 seconds.)
2. Disconnect ATP switch harness connector.
3. Remove ATP switch. Refer to DLN-16, "Component Parts Location"
.
4. Push and release ATP switch and check continuity between ATP
switch terminals 8 and 9.
Are inspection results normal?
YES >> GO TO 5.
NO >> Replace ATP switch.
5.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to DLN-81, "Reference Value"
.
Are inspection results normal?
YES >> GO TO 6.
NO >> Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
6.CHECK ATP WARNING LAMP
1. Turn ignition switch ON. (Do not start engine.)
2. Move A/T selector lever to P position.
3. Set 4WD shift switch from 4H to 4LO or 4LO to 4H.
Does ATP warning lamp turn ON while switching?
YES >> Inspection End.
NO >> GO TO DLN-109, "Diagnosis Procedure"
.
Continuity should exist.
SDIA2394E
Terminal Condition Continuity
8 - 9 Push ATP switch Yes
Release ATP switch No
SDIA2757E
Revision: December 20092009 QX56

PRECAUTIONSDLN-121
< PRECAUTION > [ATX14B]
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5. When the repair work is completed, return the ignition switch to the ″LOCK ″ position before connecting
the battery cables. (At this time, the steering lock mechanism will engage.)
6. Perform a self-diagnosis check of al l control units using CONSULT-III.
Precaution for Transfer Assembly and Transfer Control Unit ReplacementINFOID:0000000004193517
When replacing transfer assembly or transfer control uni t, check the 4WD shift indicator lamp as follows.
1. Turn ignition switch ON.
2. Check 4WD shift indicator lamp is turned ON for approximately 1 second.
 If OK, the position between transfer assemb ly and transfer control unit is correct.
 If NG, the position is different between transfer assembly and transfer control unit. Adjust the position between transfer assembly and transfer control unit. See METHOD FOR POSITION
ADJUSTMENT that follows.
METHOD FOR POSITION ADJUSTMENT
1. Start engine. Run the engine for at least 10 seconds.
2. Stop vehicle and move A/T selector lever to N position with brake pedal depressed. Stay in N for at least 2
seconds.
3. Turn 4WD shift switch to 2WD position. Stay in 2WD for at least 2 seconds.
4. Turn ignition switch OFF.
5. Start engine.
6. Erase self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)"
.
7. Check 4WD shift indicator lamp. Refer to DLN-7, "Preliminary Check"
.
If 4WD shift indicator lamp does not indicate 2WD, install new transfer control unit and retry the above
check.
PrecautionINFOID:0000000004193518
 Before connecting or disconnect ing the transfer control unit
harness connector, turn ignition switch “OFF” and disconnect
battery cables. Failure to do so may damage the transfer con-
trol unit. Battery voltage is ap plied to transfer control unit
even if ignition swit ch is turned “OFF”.
 When connecting or disconnect ing pin connectors into or
from transfer control unit, take care not to damage pin termi-
nals (bend or break).
When connecting pin connectors make sure that there are not
any bends or breaks on transfer control unit pin terminals.
SEF289H
SEF291H
Revision: December 20092009 QX56

DLN-128
< ON-VEHICLE MAINTENANCE >[ATX14B]
TRANSFER OIL FILTER
3. Apply ATF to the two new O-rings (1), and install them on the oil
filter (2).
CAUTION:
Do not reuse O-rings.
4. Install the oil filter to the transfer assembly. Tighten the bolts to the specified torque. Refer to DLN-127, "Removal and Installa-
tion".
CAUTION:
 Do not damage oil filter.
 Attach oil filter an d tighten bolts evenly.
5. Check the transfer fluid. Refer to DLN-129, "Inspection"
.
6. Start the engine for one minute. Then stop the engine and recheck the transfer fluid. Refer to DLN-129, "Inspection"
.
WDIA0285E
SDIA2136E
Revision: December 20092009 QX56

TRANSFER FLUIDDLN-129
< ON-VEHICLE MAINTENANCE > [ATX14B]
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TRANSFER FLUID
ReplacementINFOID:0000000004193523
CAUTION:
If using the vehicle for towing, the transfer fluid must be replaced as specified. Refer to MA-8, "Intro-
duction of Periodic Maintenance".
DRAINING
1. Stop engine.
2. Remove the drain plug and gasket and drain the fluid.
3. Install the drain plug with a new gasket to the transfer. Tighten to
the specified torque. Refer to DLN-142, "Disassembly and
Assembly".
CAUTION:
Do not reuse gasket.
FILLING
1. Remove the filler plug and gasket.
2. Fill the transfer with new fluid until the fluid level reaches the specified limit near the filler plug hole.
CAUTION:
Carefully fill fluid. (Fil l up for approx. 3 minutes.)
3. Leave the vehicle for 3 minutes, and check fluid level again.
4. Install the filler plug with a new gasket to the transfer. Tighten to the specified torque. Refer to DLN-142, "Disassembly and
Assembly".
CAUTION:
Do not reuse gasket.
InspectionINFOID:0000000004193524
CAUTION:
If using the vehicle for towing, the transfer fluid must be replaced as specified. Refer to MA-8, "Intro-
duction of Periodic Maintenance".
FLUID LEAKAGE AND FLUID LEVEL
1. Make sure that fluid is not leaking from the transfer assembly or around it.
2. Check fluid level from the filler plug hole as shown. CAUTION:
Do not start engine while checking fluid level.
3. Install the filler plug with a new gasket to the transfer. Tighten to the specified torque. Refer to DLN-142, "Disassembly and
Assembly".
CAUTION:
Do not reuse gasket.
SDIA3208E
Fluid grade and capacity : Refer to MA-12, "Fluids and
Lubricants".
SDIA3209E
SDIA3209E
Revision: December 20092009 QX56

DLN-140
< ON-VEHICLE REPAIR >[ATX14B]
TRANSFER MOTOR
TRANSFER MOTOR
Removal and InstallationINFOID:0000000004193531
REMOVAL
1. Disconnect the transfer motor connector.
2. Remove the transfer motor air breather hose from the transfer
motor. Refer to DLN-137, "Removal and Installation"
.
3. Remove the transfer motor bolts.
4. Remove the transfer motor.
INSTALLATION
1. Apply ATF to the new O-ring and install it to the transfer motor. CAUTION:
Do not reuse O-rings.
2. Fit the double-flat end of the transfer motor shaft into the slot of the sub-oil pump assembly. Then tighten to the specified torque.
Refer to DLN-140, "Removal and Installation"
.
CAUTION:
Be sure to install connector bracket.
3. Install the transfer motor air breather hose to the transfer motor. Refer to DLN-137, "Removal and Installation"
.
4. Connect the transfer motor connector.
5. Check the transfer fluid. Refer to DLN-129, "Replacement"
.
6. Start the engine for one minute. Then stop the engine and recheck the transfer fluid. Refer to DLN-129,
"Inspection".
SDIA2133E
SDIA2787E
Revision: December 20092009 QX56

TRANSFER ASSEMBLYDLN-141
< REMOVAL AND INSTALLATION > [ATX14B]
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REMOVAL AND INSTALLATION
TRANSFER ASSEMBLY
Removal and InstallationINFOID:0000000005874982
REMOVAL
1. Set transfer state as 2WD when 4WD shift switch is at 2WD.
2. Remove the undercovers using power tool.
3. Drain the transfer fluid. Refer to DLN-129, "Replacement"
.
4. Remove the center exhaust tube and main muffler. Refer to EX-6, "Removal and Installation"
.
5. Remove the front and rear propeller shafts. Refer to DLN-186, "Removal and Installation"
(front), DLN-
196, "Removal and Installation" (rear).
CAUTION:
Do not damage spline, sleeve yoke and rear oi l seal when removing rear propeller shaft.
NOTE:
Insert a plug into the rear oil seal after removing the rear propeller shaft.
6. Remove the A/T nuts from the A/T crossmember. Refer to TM-216, "Removal and Installation (4WD)"
.
7. Position two suitable jacks under the A/T and transfer assembly.
8. Remove the crossmember. Refer to TM-216, "Removal and Installation (4WD)"
.
WARNING:
Support A/T and transfer assembly using two suitable jacks while removing crossmember.
9. Disconnect the electrical c onnectors from the following:
 ATP switch
 Neutral 4LO switch
 Wait detection switch
 Transfer motor
 Transfer control device
 Transfer terminal cord assembly
10. Disconnect each air breather hose from the following. Refer to DLN-137, "Removal and Installation"
.
 Actuator
 Breather tube (transfer)
 Transfer motor
11. Remove the transfer control dev ice from the extension housing.
12. Remove the transfer to A/T and A/T to transfer bolts.
13. Remove the transfer assembly. WARNING:
Support transfer assembly with su itable jack while removing it.
CAUTION:
Do not damage rear oil seal (A/T).
INSTALLATION
Installation is in the reverse order of removal.
 Tighten the bolts to specification.
 Fill the transfer with new fluid and check for fluid leakage and fluid level. Refer to DLN-129, "Replacement"
.
 Start the engine for one minute. Then stop the engine and recheck the transfer fluid. Refer to DLN-129, "Inspection"
.
Transfer bolt torque : 36 N·m (3.7 kg-m, 27 ft-lb)
SMT872C
Revision: December 20092009 QX56