2008 INFINITI QX56 warning

DLN-2
P1820 ENGINE SPEED SIGNAL ......................52
Description ........................................................... ...52
DTC Logic ...............................................................52
Diagnosis Procedure ..............................................52
P1822 CLUTCH PRESSURE SOLENOID .........53
Description ..............................................................53
DTC Logic ...............................................................53
Diagnosis Procedure ..............................................53
Component Inspection ............................................55
P1823 2-4 SOLENOID .......................................57
Description ........................................................... ...57
DTC Logic ...............................................................57
Diagnosis Procedure ..............................................57
Component Inspection ............................................60
P1824 TRANSFER MOTOR ..............................61
Description ..............................................................61
DTC Logic ...............................................................61
Diagnosis Procedure ..............................................61
Component Inspection ............................................65
P1826 TRANSFER FLUID TEMPERATURE ....67
Description ........................................................... ...67
DTC Logic ...............................................................67
Diagnosis Procedure ..............................................67
Component Inspection ............................................68
P1827 CLUTCH PRESSURE SWITCH .............70
Description ........................................................... ...70
DTC Logic ...............................................................70
Diagnosis Procedure ..............................................70
Component Inspection ............................................71
P1828 LINE PRESSURE SWITCH ....................73
Description ........................................................... ...73
DTC Logic ...............................................................73
Diagnosis Procedure ..............................................73
Component Inspection ............................................75
P1829 THROTTLE POSITION SIGNAL (ECM)
...
76
Description ........................................................... ...76
DTC Logic ...............................................................76
Diagnosis Procedure ..............................................76
P1830 ABS OPERATION SIGNAL (ABS) ........77
Description ........................................................... ...77
DTC Logic ...............................................................77
Diagnosis Procedure ..............................................77
P1831 VDC OPERATION SIGNAL (ABS) ........78
Description ........................................................... ...78
DTC Logic ...............................................................78
Diagnosis Procedure ..............................................78
P1832 TCS OPERATION SIGNAL (ABS) .........79
Description ........................................................... ...79
DTC Logic ...............................................................79
Diagnosis Procedure ..............................................79
ECU DIAGNOSIS .......................................80
TRANSFER CONTROL UNIT ...........................80
Reference Value .................................................. ...80
Wiring Diagram .......................................................88
DTC Index ...............................................................95
SYMPTOM DIAGNOSIS ...........................100
4WD SYSTEM SYMPTOMS ........................... ..100
Symptom Table .................................................... .100
4WD SHIFT INDICATOR LAMP AND 4LO IN-
DICATOR LAMP DO NOT TURN ON ..............
101
Description ............................................................101
Diagnosis Procedure .............................................101
4WD WARNING LAMP DOES NOT TURN ON ..103
Description ........................................................... .103
Diagnosis Procedure .............................................103
4WD SHIFT INDICATOR LAMP OR 4LO INDI-
CATOR LAMP DO NOT CHANGE ...................
105
Description ........................................................... .105
Diagnosis Procedure .............................................105
ATP WARNING LAMP DOES NOT TURN ON ..107
Description ........................................................... .107
Diagnosis Procedure .............................................107
4WD SHIFT INDICATOR LAMP KEEPS
FLASHING ........................................................
109
Description ........................................................... .109
Diagnosis Procedure .............................................109
4WD WARNING LAMP FLASHES RAPIDLY ..110
Description ............................................................110
Diagnosis Procedure .............................................110
4WD WARNING LAMP FLASHES SLOWLY ..111
Description ............................................................111
Diagnosis Procedure .............................................111
HEAVY TIGHT-CORNER BRAKING SYMP-
TOM OCCURS ................................................ ..
112
Description ........................................................... .112
Diagnosis Procedure .............................................112
ATP SWITCH ....................................................114
Description ........................................................... .114
Diagnosis Procedure .............................................114
4WD SYSTEM DOES NOT OPERATE ............116
Description ........................................................... .116
Diagnosis Procedure .............................................116
NOISE, VIBRATION AND HARSHNESS
(NVH) TROUBLESHOOTING ...........................
117
NVH Troubleshooting Chart ..................................117
PRECAUTION ............... ............................118
Revision: March 2010 2008 QX56

DIAGNOSIS AND REPAIR WORKFLOWDLN-7
< BASIC INSPECTION > [ATX14B]
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>> GO TO 4
4.SYMPTOM
Check for symptoms. Refer to DLN-100, "
Symptom Table".
>> GO TO 5
5.MALFUNCTIONING PARTS
Repair or replace the applicable parts.
>> GO TO 6
6.SYSTEM OPERATION
Check system operation.
>> GO TO 7
7.SELF-DIAGNOSIS
Perform self-diagnosis.
Are any DTC's displayed?
YES >> GO TO 5
NO >> Inspection End
Preliminary CheckINFOID:0000000001737095
TRANSFER FLUID CHECK
Check for leaks and fluid level. Refer to DLN-127, "Inspection".
PREPARATION FOR ROAD TEST
The purpose of the test is to determine overall performance of trans-
fer case and analyze causes of malfunctions.
When a malfunction is found in any part of transfer, perform the road
test to locate the malfunction area and repair the malfunction parts.
The road test consists of the following three parts.
1. CHECK BEFORE ENGINE IS STARTED
2. CHECK AT IDLE
3. CRUISE TEST
CHECK BEFORE ENGINE IS STARTED
1.CHECK 4WD SHIFT INDICATOR LAMP
1. Park vehicle on flat surface.
2. Turn ignition switch to OFF position.
3. Move A/T selector lever to P position.
4. Set 4WD shift switch to 2WD position.
5. Turn ignition switch to ON position. (Do not start engine.)
Does 4WD shift indicator lamp turn ON for approximately 1 second?
YES >> GO TO 2.
NO >> GO TO DLN-101, "
Diagnosis Procedure".
2.CHECK 4WD WARNING LAMP
1. Turn ignition switch to OFF position.
2. Move A/T selector lever to P position.
3. Set 4WD shift switch to 2WD position.
4. Turn ignition switch to ON position. (Do not start engine.)
SMT089D
Revision: March 2010 2008 QX56

DLN-8
< BASIC INSPECTION >[ATX14B]
DIAGNOSIS AND REPAIR WORKFLOW
Does 4WD warning lamp turn ON?
YES >> GO TO CHECK AT IDLE.
NO >> GO TO
DLN-103, "
Diagnosis Procedure".
CHECK AT IDLE
1.CHECK 4WD SHIFT INDICATOR LAMP
1. Park vehicle on flat surface and engage the parking brake.
2. Turn ignition switch to OFF position.
3. Move A/T selector lever to P position.
4. Set 4WD shift switch to 2WD position.
5. Start engine.
Does 4WD shift indicator lamp turn ON?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK 4WD WARNING LAMP
Check 4WD warning lamp state.
Is 4WD warning lamp turned ON?
YES >> Perform the self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)".
NO >> Refer to DLN-105, "
Diagnosis Procedure".
3.CHECK 4WD SHIFT INDICATOR AND 4LO INDICATOR OPERATION
1. Brake pedal depressed.
2. Move A/T selector lever to N position.
3. Set 4WD shift switch to 2WD, AUTO, 4H, 4LO, 4H, AUTO and 2WD in order. (Stay at each switch position for at least 1 sec-
ond.)
Do 4WD shift indicator and 4LO indicator lamps change properly?
Does buzzer sound?
YES >> GO TO CRUISE TEST.
NO >> GO TO DLN-105, "
Diagnosis Procedure".
CRUISE TEST
1.CHECK INPUT SIGNAL
1. Warm up engine to normal operating temperature.
2. Park vehicle on flat surface.
3. Move A/T selector lever to P position.
4. Set 4WD shift switch to AUTO position.
5. Start engine.
6. Drive vehicle for at least 30 seconds at a speed higher than 20 km/h (12 MPH).
Is 4WD warning lamp turned ON?
On steady>>Perform the self-diagnosis. Refer to DLN-18, "CONSULT-III Function (ALL MODE AWD/4WD)".
WDIA0136E
Revision: March 2010 2008 QX56

DLN-10
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
FUNCTION DIAGNOSIS
4WD SYSTEM
System DiagramINFOID:0000000001737096
COMPONENT DESCRIPTION
WDIA0164E
Components
Function
Transfer control unit Controls transfer control device, control valves and shifts between 2WD/4WD and 4H/4LO.
Transfer control device Integrates actuator motor and actuator position switch.
2-4WD shift solenoid valve Controls oil pressure and allows shifting between 2WD and 4WD.
Clutch pressure solenoid valve Controls oil pressure and distributes torque between front and rear tires.
Line pressure switch Detects line pressure.
Clutch pressure switch Detects clutch pressure.
Transfer fluid temperature sensor Detects transfer fluid temperature.
Actuator motor Moves shift rods when signaled by transfer control unit.
Actuator position switch Detects actuator motor position.
Wait detection switch Detects whether or not 4WD lock gear is locked.
4LO switch Detects if transfer case is in 4LO.
ATP switch Detects if transfer case is in neutral.
4WD shift switch Allows driver to select from 2WD/4WD, 4H/4LO and AUTO.
4WD warning lamp • Illuminates if malfunction is detected in 4WD system.
• Flashes (1 flash / 2 seconds) if large difference in diameter of front and rear tires.
• Flashes (2 flashes / 1 second) if high transfer fluid temperature is detected.
AT P w a r n i n g l a m p Indicates that A/T parking mechanism does not operate when A/T selector lever is in P position
because transfer case is in neutral.
4WD shift indicator lamp Displays driving range selected by 4WD shift switch.
4LO indicator lamp Displays 4LO range.
Revision: March 2010 2008 QX56

4WD SYSTEMDLN-13
< FUNCTION DIAGNOSIS > [ATX14B]
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Hydraulic Control Circuits
TRANSFER CONTROL UNIT
• Transfer control unit controls transfer control dev
ice and it directs shifts from 4H-4LO and 2WD-4WD.
• Self-diagnosis can be done.
TRANSFER SHIFT HIGH AND LOW RELAYS
Transfer shift high and low relays apply power supply to transfer control device (actuator motor).
TRANSFER SHUT OFF RELAY
Transfer shut off relay applies power supply to transfer motor relay.
4WD SHIFT SWITCH AND INDICATOR LAMPS
4WD Shift Switch
Able to select from 2WD, AUTO, 4H or 4LO.
4WD Shift Indicator Lamp
• Displays driving conditions selected by 4WD shift switch with 2WD, AUTO and 4H indicators while engine is running. (When 4WD warning lamp is turned on, all 4WD shift indicator lamps are turned off.)
• Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4LO Indicator Lamp
LDIA0055E
WDIA0163E
Revision: March 2010 2008 QX56

DLN-14
< FUNCTION DIAGNOSIS >[ATX14B]
4WD SYSTEM
• Displays 4LO condition while engine is running. 4LO indicator lamp flashes if transfer gear does not shift
completely under 2WD, AUTO, 4H ⇔4LO. (When 4WD warning lamp is turned on, 4LO indicator lamp is
turned off.)
• Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4WD WARNING LAMP
Turns on or flashes when there is a malfunction in 4WD system.
Also turns on when ignition switch is turned ON, for purpose of lamp che\
ck. Turns OFF approximately 1 sec-
ond after the engine starts if system is normal.
4WD Warning Lamp Indication
ATP WARNING LAMP
When the A/T selector lever is in P position, the vehicle may move if the transfer case is in neutral. ATP warn-
ing lamp is turned on to indicate this condition to the driver.
LINE PRESSURE SWITCH
• With the transfer system design, control of the oil pressure provides the transmission of drive torque to the
front wheels. The main pressure to control the oil pressure is referred to as the line pressure.
• The line pressure switch determines whether or not adequate line pressure has built up under different oper- ating conditions.
• The line pressure switch closes when line pressure is produced.
• The line pressure switch senses line pressure abnormalities and turns the 4WD warning lamp ON.
CLUTCH PRESSURE SWITCH
• The clutch pressure switch determines whether or not adequate clutch pressure has built up under different
operating conditions.
• The clutch pressure switch closes when clutch pressure is produced.
• The clutch pressure switch senses clutch pressure abnormalities and turns the 4WD warning lamp ON.
WAIT DETECTION SWITCH
• The wait detection switch operates when there is circulating torque produced in the propeller shaft (L→H) or
when there is a phase difference between 2-4 sleeve and clutch drum (H →L). After the release of the circu-
lating torque, the wait detection switch helps provi de the 4WD lock gear (clutch drum) shifts. A difference
may occur between the operation of the 4WD shift swit ch and actual drive mode. At this point, the wait
detection switch senses an actual drive mode.
• The wait detection switch operates as follows.
- 4WD lock gear (clutch drum) locked: ON
- 4WD lock gear (clutch drum) released: OFF
• The wait detection switch senses an actual drive mode and the 4WD shift indicator lamp indicates the vehi-
cle drive mode.
ATP SWITCH
ATP switch detects if transfer case is in neutral by the position of the L-H shift fork.
NOTE:
Transfer case may be in neutral when shifting between 4H-4LO.
NEUTRAL-4LO SWITCH
The neutral-4LO switch detects that transfer gear is in neutral or 4LO (or shifting from neutral to 4LO) condi-
tion by L-H shift fork position.
Condition 4WD warning lamp
System normal OFF
Lamp check Turns ON when ignition switch is turned ON.
Turns OFF after engine start.
4WD system malfunction ON
During self-diagnosis Flashes malfunction mode.
Large difference in diameter of front/
rear tires Flashes slow (1 flash / 2 seconds)
(Continues to flash until the ignition switch is turned OFF)
High fluid temperature in transfer case Flashes rapidly (2 flashes / 1 second)
(Continues to flash until fluid temperature returns to normal)
Revision: March 2010 2008 QX56

4WD SYSTEMDLN-17
< FUNCTION DIAGNOSIS > [ATX14B]
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CAN CommunicationINFOID:0000000001737099
Refer to LAN-51, "DTC Index".
1. A: Transfer shut off relay E69
B: Transfer shift low relay E47
C: Transfer shift high relay E46 2. A: Actuator
B: Transfer control device F58
C: Actuator lever
D: Transfer case 3. Wait detection switch F59
(View with transfer case removed)
4. A: Clutch pressure switch B: Line pressure switch
C: Transfer fluid temperature sensor
D: 2-4WD shift solenoid valve
E: Clutch pressure solenoid valve
(View with contro l valve removed
from transfer case) 5. A: Neutral 4LO switch F60
B: ATP switch F55
C: Transfer motor F57
D: Transfer terminal cord assembly F56
E: Oil filter 6. Combination meter M23, M24
A: 4WD warning lamp
B: ATP warning lamp
C: 4LO indicator lamp (located in in-
formation display)
D: 4WD shift indicator lamp
7. 4WD shift switch M141 8. Transfer control unit E142, E143 9. Transfer dropping resistor E135
Transfer motor relay E153, E154
(View with battery removed)
Revision: March 2010 2008 QX56

DLN-18
< FUNCTION DIAGNOSIS >[ATX14B]
DIAGNOSIS SYSTEM (T
RANSFER CONTROL UNIT)
DIAGNOSIS SYSTEM (TRA NSFER CONTROL UNIT)
CONSULT-III Function (ALL MODE AWD/4WD)INFOID:0000000001737100
FUNCTION
CONSULT-III can display each diagnostic item us ing the diagnostic test modes shown following.
SELF-DIAG RESULT MODE
Operation Procedure
1. Connect CONSULT-III.
2. With engine at idle, touch SELF-DIAG RESULTS.
Display shows malfunction experienced since the last erasing operation.
NOTE:
The details for TIME are as follows:
• 0: Error currently detected with transfer control unit.
• Except for 0: Error detected in the pa st and memorized with transfer control unit.
Detects frequency of driving after DTC occurs (frequency of turning ignition switch ON/OFF).
How to Erase Self-d iagnostic Results
1. Perform applicable inspection of malfunctioning item and then repair or replace.
2. Start engine and select SELF-DIAG RESULTS m ode for ALL MODE AWD/4WD with CONSULT-III.
3. Touch ERASE on CONSULT-III screen to erase DTC memory. CAUTION:
If memory cannot be erased, pe rform applicable diagnosis.
SELF-DIAGNOSTIC PROCEDURE (WITHOUT CONSULT-III)
Description
If the engine starts when there is a malfunction in the 4WD system, the 4WD warning lamp turns ON or flickers
in the combination meter. When the system functions properly, the warning lamp turns ON when the ignition
switch is turned to ON, and it turns OFF after engine starts . To locate the cause of a malfunction, start the self-
diagnosis function. The 4WD warning lamp in the combination meter will indicate the malfunction area by
flashing according to the self-diagnostic results. Refer to DLN-95, "
DTC Index".
Diagnostic Procedure
1. Warn up engine.
2. Move A/T selector lever to P position.
3. Turn 4WD shift switch to 2WD position.
4. Turn ignition switch ON and OFF at least twice, and then turn ignition switch OFF.
5. Turn 4WD shift switch to AUTO position.
6. Turn ignition switch ON. (Do not start engine.)
7. 4WD warning lamp ON.
8. Move A/T selector lever to R position.
9. Turn 4WD shift switch to 2WD, AUTO and 2WD in order.
10. Move A/T selector lever to D position.
11. Turn 4WD shift switch to 4H, AUTO and 4H in order.
ALL MODE AWD/4WD diagnostic mode Description
SELF-DIAG RESULTS Displays transfer control unit self-diagnosis results. DATA MONITOR Displays transfer control unit input/output data in real time.
WORK SUPPORT Supports inspections and adjustments. Commands are transmitted to the transfer control
unit for setting the status suitable for required operation, input/output signals are received
from the transfer control unit and received data is displayed.
CAN DIAG SUPPORT MNTR The results of transmit/receive diagnosis of CAN communication can be read. ECU PART NUMBER Transfer control unit part number can be read.
Revision: March 2010 2008 QX56