INFINITI QX4 2005 Factory Service Manual

RSU-6
CAN COMMUNICATION
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CAN COMMUNICATIONPFP:23710
System DescriptionEES001H2
Refer to LAN-5, "CAN COMMUNICATION" .

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How to Perform Trouble Diagnoses for Quick and Accurate RepairEES001H3
INTRODUCTION
The rear load leveling air suspension system uses an electronic con-
trol unit to control major functions. The control unit accepts input sig-
nals from the height sensor and controls compressor and exhaust
valve operation.
It is much more difficult to diagnose a rear load leveling air suspen-
sion system problem that occurs intermittently rather than continu-
ously. Most intermittent problems are caused by poor electrical
connections or faulty wiring. In this case, careful checking of suspi-
cious circuits may help prevent the replacement of good parts.
Before undertaking actual checks, take just a few minutes to talk with
a customer who approaches with an air suspension system com-
plaint. The customer is a very good source of information on such
problems, especially intermittent ones. Through discussion with the
customer, find out what symptoms are present and under what con-
ditions they occur.
Start your diagnosis by looking for basic mechanical problems first.
This is one of the best ways to troubleshoot concerns on an air sus-
pension system equipped vehicle. Also check related Service Bulle-
tins for information.
CLARIFY CONCERN

A customer's description of a vehicle concern may vary depend-
ing on the individual. It is important to clarify the customer's con-
cern.

Ask the customer about what symptoms are present under what
conditions. Use this information to reproduce the symptom.
SEF 2 33 G
SEF 2 34 G
SBR3 39 B

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WORK FLOW
WEIA0077E

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Component Parts and Harness Connector LocationEES001H4
WEIA0140E

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Wiring Diagram — A/SUSP —EES001H5
WEWA0026E

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WEWA0063E

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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

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CONSULT-II Function (AIR LEVELIZER)EES001H9
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
CONSULT-II BASIC OPERATION PROCEDURE
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.
1. Turn ignition switch OFF.
2. Connect CONSULT-II and CONSULT-II CONVERTER to the
data link connector.
3. Turn ignition switch ON.
4. Touch "START (NISSAN BASED VHCL)".
5. Touch "AIR LEVELIZER" in the "SELECT SYSTEM" screen.
If "AIR LEVELIZER" is not indicated, go to GI-39, "
CONSULT-II
Data Link Connector (DLC) Circuit" .
AIR LEVELIZER
diagnostic modeDescription
WORK SUPPORTSupports inspection and adjustments. Commands are transmitted to the suspension control unit for
setting the status suitable for required operation, input/output signals are received from the suspen-
sion control unit and received data is displayed.
SELF-DIAG RESULTS Displays suspension control unit self-diagnosis results.
DATA MONITOR Displays suspension control unit input/output data in real time.
ACTIVE TEST Operation of electrical loads can be checked by sending drive signal to them.
ECU PART NUMBER Suspension control unit part number can be read.
BBIA0369E
BCIA0029E
BCIA0030E

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6. Select the required operation from the "SELECT DIAG MODE"
screen.
For further information, see the CONSULT-II Operation Manual.
WORK SUPPORT
Operation Procedure
1. Touch “AIR LEVELIZER” on “SELECT SYSTEM” screen.
2. Touch “WORK SUPPORT” on “SELECT DIAG MODE” screen.
3. Touch item on “SELECT WORK ITEM” screen.
4. Touch “START”.
5. The setting will be changed and “ADJUSTMENT COMPLETE” will be displayed.
6. Touch “END”.
Display Item List
SELF-DIAGNOSIS
Description
If an error is detected in the system, perform self-diagnosis as follows:
Operation Procedure
1. Turn ignition switch OFF.
2. Connect CONSULT-II and 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.
3. Turn ignition switch ON.
4. After stopping the vehicle, with the engine running, touch "START (NISSAN BASED VHCL)", "AIR LEV-
ELIZER", "SELF-DIAG RESULTS" in order on the CONSULT-II screen.
CAUTION:
If "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 1.
5. The self-diagnostic results are displayed. (If necessary, the self-diagnostic results can be printed out by
touching "COPY".)

When "NO DTC IS DETECTED" is displayed, check the CK SUSP indicator lamp.
6. Conduct the appropriate inspection from the display item list, and repair or replace the malfunctioning
component.
7. Start and run the vehicle for approximately 1 minute.
8. Turn ignition switch OFF to prepare for erasing the memory.
9. Start the engine and touch "START (NISSAN BASED VHCL)", "AIR LEVELIZER", "SELF-DIAG
RESULTS", "ERASE" in order on the CONSULT-II screen to erase the error memory.
If "AIR LEVELIZER" is not indicated, go to GI-39, "
CONSULT-II Data Link Connector (DLC) Circuit" .
BCIA0031E
Item Description
STANDARD HEIGHT LEVEL This mode allows the vehicle height to be set to vehicle height specification within tolerance.
ADJUST HEIGHT INI The initialization value and flag can be set in the suspension control unit in this mode.
CLEAR HEIGHT INI This mode clears the initialization flag and value in the suspension control unit.

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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" .