2005 INFINITI QX4 relay

RSU-12
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Basic InspectionEES001H6
AIR HOSES
1. Check for pinched or damaged air hoses between the suspension air reservoir and each load leveling rear
air suspension shock absorber. Reposition, repair or replace hoses as necessary.
2. Check the air hose connections at the suspension air reservoir and at the shock absorbers for leaks. If
connections are leaking, repair or replace hoses as necessary.
POWER SYSTEM TERMINAL LOOSENESS AND BATTERY INSPECTION
Make sure the battery positive cable, negative cable and ground connection are not loose. In addition, make
sure the battery is sufficiently charged.
CK SUSP INDICATOR LAMP INSPECTION
1. Make sure the CK SUSP indicator lamp turns on for approximately 2 seconds when the ignition switch is
turned ON. If it does not, check the combination meter. Refer to DI-5, "
COMBINATION METERS" .
2. Make sure the lamp turns off approximately 2 seconds after the ignition switch is turned ON. If the lamp
does not turn off, conduct self-diagnosis of the suspension control unit.
3. After conducting the self-diagnosis, be sure to erase the error memory. Refer to RSU-13, "
CONSULT-II
Function (AIR LEVELIZER)" .
CK SUSP Indicator Lamp TimingEES001H7
X: ON
—: OFF
Control Unit Input/Output Signal StandardEES001H8
( ): Wire colorConditionCK SUSP
indicator lampRemarks
Ignition switch OFF – –
Ignition switch ON X Turns off after approximately 2 seconds.
Te r m i n a l
Item ConditionVoltage (V)
(Approx.)
+–
1 (V)
GroundCompressor relay output
Ignition switch ON or STARTBattery voltage
3 (W) Height sensor signal input 0.2V - 4.8V
5 (R) Reference voltage 5V
6 (G/R) Ignition power
Battery voltage
7 (W/L) Battery power —
8 (G/W) Diagnostic K-line — —
9 (SB) Exhaust valve output Ignition switch ON or START Battery voltage
10 (BR) Warning lamp output — —
14 (L) Height sensor ground — —
15 (BR/W) Alternator L signal input Engine running —
16 (B) Suspension control unit ground — 0V

TROUBLE DIAGNOSIS
RSU-15
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Revision: October 20052005 QX56
CAUTION:
If the error memory is not erased, re-conduct the operation from step 7.
10. For the final inspection, start and run the vehicle for approximately 1 minute and confirm that the CK
SUSP indicator lamp is off.
Display Item List
DATA MONITOR
Operation Procedure
1. After turning OFF the ignition switch, connect CONSULT-II and the CONSULT-II CONVERTER to the data
link connector.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carries out CAN communication.
2. Touch "START (NISSAN BASED VHCL)", "AIR LEVELIZER", "DATA MONITOR" in order on the CON-
SULT-II screen.
If "AIR LEVELIZER" is not indicated, go to GI-39, "
CONSULT-II Data Link Connector (DLC) Circuit" .
CAUTION:
When "START (NISSAN BASED VHCL)" is touched immediately after starting the engine or turning
on the ignition switch, "AIR LEVELIZER" might not be displayed in the "SELECT SYSTEM" screen.
In this case, repeat the operation from step 2.
3. Return to the "SELECT MONITOR ITEM" screen, and touch "ALL SIGNALS" or "SELECTION FROM
MENU". Refer to the following information.
4. When "START" is touched, the data monitor screen is displayed.
Self-diagnostic item Malfunction detecting condition Check system
Vehicle height sensor
[C1801]Vehicle height sensor voltage is less than 0.2V or greater than
4.8V for more than 60 seconds.Refer to RSU-17, "
Height
Sensor System Inspection" .
Compressor relay
[C1802]1. Driving transistor for compressor relay is off and monitor volt-
age continues high level for more than 10 seconds.
2. Driving transistor for compressor relay is on and monitor volt-
age continues low level for more than 5 seconds.Refer to RSU-20, "
Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .
Exhaust solenoid
[C1803]1. Driving transistor for exhaust solenoid is off and monitor volt-
age continues high level for more than 10 seconds.
2. Driving transistor for exhaust solenoid is on and monitor volt-
age continues low level for more than 5 seconds.Refer to RSU-19, "
Exhaust
Valve Solenoid System
Inspection" .
Vehicle height adjusting trouble
(compressor)
[C1804]Continuous compressor relay ON time is more than 120 sec-
onds.Refer to RSU-20, "
Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .
Vehicle height adjusting trouble
(exhaust solenoid)
[C1805]Continuous exhaust solenoid ON time is more than 120 seconds.Refer to RSU-19, "
Exhaust
Valve Solenoid System
Inspection" .
Vehicle height sensor locking trou-
ble
[C1806]Output sensor voltage variation ±0.02V is more than 100 hour
when vehicle height range is normal.Refer to RSU-17, "
Height
Sensor System Inspection" .
Sensor 5V trouble
[C1807]Sensor reference voltage is less than 0.8V or more than 6V for
20 seconds.Refer to RSU-17, "
Height
Sensor System Inspection" .
Integral time trouble by supplying
air
[C1808]Integral discontinuous time on the compressor is more than 180
seconds.Refer to RSU-20, "
Compres-
sor Motor, Compressor
Motor Relay and Circuit
Inspection" .

RSU-20
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: October 20052005 QX56
5. EXHAUST VALVE SOLENOID INSPECTION
Apply 12V to suspension air compressor C9 terminal 2 and body
ground to suspension air compressor C9 terminal 1.
OK or NG
OK >> GO TO 6.
NG >> Replace the suspension air compressor. Refer to RSU-
42, "REAR LOAD LEVELING AIR SUSPENSION COM-
PRESSOR ASSEMBLY" .
6. CHECK EXHAUST VALVE SOLENOID POWER AND GROUND
1. Reconnect the suspension control unit connector.
2. Turn the ignition switch ON.
3. Check voltage between suspension air compressor connector
C9 terminal 2 (SB) and ground.
4. Check resistance between suspension air compressor connec-
tor C9 terminal 1 (B) and ground.
OK or NG
OK >> Replace the suspension control unit. Refer to RSU-46,
"CONTROL UNIT" .
NG >> Repair the circuit.
Compressor Motor, Compressor Motor Relay and Circuit InspectionEES001HC
INSPECTION PROCEDURE
1. SELF-DIAGNOSIS RESULT CHECK
Check self-diagnosis results.
Is the above displayed in the self-diagnosis display items?
YES >> If code C1802 was retrieved during self-diagnosis, GO TO 3. If code C1804 or C1808 was
retrieved during self-diagnosis, GO TO 2.
NO >> Inspection End.System air pressure should vent.
WEIA0063E
Voltage : Approx. 12V
WEIA0088E
Continuity should exist.
WEIA0089E
Self-diagnosis results
C1802
C1804
C1808

TROUBLE DIAGNOSES FOR SYMPTOMS
RSU-23
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Revision: October 20052005 QX56
TROUBLE DIAGNOSES FOR SYMPTOMSPFP:99999
Load Leveling Rear Air Suspension System Does Not OperateEES001HD
1. CHECK WARNING LAMP ACTIVATION
Make sure warning lamp remains off while driving.
OK or NG
OK >> GO TO 2.
NG >> Carry out self-diagnosis. Refer to RSU-14, "
SELF-DIAGNOSIS" .
2. CHECK FUSES
Check that the following fuses are not blown.
OK or NG
OK >> GO TO 3.
NG >> If fuse is blown, be sure to eliminate cause of blown fuse before installing new fuse. Refer to PG-
4, "POWER SUPPLY ROUTING CIRCUIT" .
3. CHECK SUSPENSION CONTROL UNIT POWER AND GROUND
1. Turn the ignition switch ON.
2. Check voltage between suspension control unit connector B3
terminal 6 (G/R) and ground and between suspension control
unit connector B3 terminal 7 (W/L) and ground.
3. Check resistance between suspension control unit connector B3
terminal 16 (B) and ground.
OK or NG
OK >> GO TO 4.
NG >> Repair the circuit.
Unit Terminals Signal name Fuse or Fusible Link
Suspension control unit6 Ignition switch ON or START 12 (10A)
7
Battery power29 (10A)
Compressor motor relay 5 g (30A)
Combination meter24 Ignition switch ON or START 14 (10A)
8 Battery power 19 (10A)
Voltage : Approx. 12V
WEIA0069E
Continuity should exist.
WEIA0070E

SC-10
STARTING SYSTEM
Revision: October 20052005 QX56
STARTING SYSTEMPFP:23300
System DescriptionEKS00B7B
Power is supplied at all times:

through 40A fusible link (letter m , located in the fuse and fusible link box)

to ignition switch terminal B.
With the ignition switch in the START position, power is supplied:

from ignition switch terminal ST

to IPDM E/R terminal 21.
With the ignition switch in the ON or START position, power is supplied to IPDM E/R (intelligent power distribu-
tion module engine room) CPU.
With the selector lever in the P or N position, power is supplied:

through A/T assembly terminal 9

to IPDM E/R terminal 48.
Ground is supplied at all times:

to IPDM E/R terminals 38 and 59

through body grounds E9, E15 and E24.
Then the starter relay is turned on.
The IPDM E/R is energized and power is supplied:

from terminal 19 of the IPDM E/R

to terminal 1 of the starter motor windings.
The starter motor plunger closes and provides a closed circuit between the battery and the starter motor. The
starter motor is grounded to the cylinder block. With power and ground supplied, the starter motor operates.

STARTING SYSTEM
SC-15
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Revision: October 20052005 QX56
DIAGNOSTIC PROCEDURE 2
Check Magnetic Switch Circuit
1. CHECK POWER SUPPLY FOR MAGNETIC SWITCH
1. Remove the fuel pump fuse.
2. Crank or start the engine (where possible) until the fuel pressure is released.
3. Turn the ignition switch OFF.
4. Disconnect starter motor connector F28.
5. Check voltage between starter motor connector F28 terminal 1
(W/R) and ground using a digital circuit tester.
OK or NG
OK >> GO TO 2.
NG >> Check the following.

40A fusible link (letter m , located in fuse and fusible
link box)

Ignition switch

Starter relay [within the intelligent power distribution module engine room (IPDM E/R)]

Harness for open or short
2. CHECK VOLTAGE DROP ON MAGNETIC SWITCH CIRCUIT
1. Turn the ignition switch OFF.
2. Connect starter motor connector F28.
3. Check voltage between starter motor connector F28 terminal 1
(W/R) and battery positive terminal using a digital circuit tester.
OK or NG
OK >> Magnetic switch circuit is OK. Further inspection is nec-
essary. Refer to SC-13, "
WORK FLOW" .
NG >> Check harness between the battery and the magnetic
switch for poor continuity. Ignition switch in
START.: Battery voltage
WKIA2108E
Ignition switch in
START.: Less than 1V
WKIA1792E

AUTOMATIC DRIVE POSITIONER
SE-11
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Revision: October 20052005 QX56
AUTOMATIC DRIVE POSITIONERPFP:28491
Component Parts And Harness Connector LocationEIS0058U
1. Fuse block (J/B) 2. Fuse and relay box 3. Fuse and fusible link box
4. A. Automatic drive positioner control
unit M33, M34
B. Pedal adjusting motor E109,
E1105. A. Steering column
B. Key switch and key lock solenoid
M27
C. BCM M18, M19, M20 (view with
instrument panel removed)6. A. Door mirror remote control switch
D10
B. Seat memory switch D5
LIIA2361E

TF-16
ALL-MODE 4WD SYSTEM
Revision: October 20052005 QX56
ALL-MODE 4WD Transfer Basic Control
Hydraulic Control Circuits
TRANSFER MOTOR

The transfer motor drives the sub-oil pump to provide proper lubrication and oil pressure control when the
vehicle is at standstill, during low-speed operations or is being driven in reverse.

The main oil pump is operated by the driving force of the mainshaft. In other words, sufficient oil pressure
buildup does not occur when the vehicle is at standstill or during low-speed operations. While the vehicle
is being driven in reverse, the main oil pump rotates in the reverse direction. Therefore the main oil pump
does not discharge oil pressure. During any of the above vehicle operations, the transfer motor drives the
sub-oil pump to compensate for insufficient oil pressure.

The transfer motor operates as follows.
–The motor relay turns OFF in the 2WD mode.
–The motor relay operates as described in the table below in modes other than the 2WD mode.
LDIA0055E
WDIA0163E