Engine Control System INFINITI QX56 2004 Factory Service Manual

ENGINE MAINTENANCE
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3. Open the radiator drain plug at the bottom of the radiator, and
remove the radiator filler cap. This is the only step required
when partially draining the cooling system (radiator only).
CAUTION:
Do not to allow the coolant to contact the drive belts.
4. When draining all of the coolant in the system for engine
removal or repair, it is necessary to drain the cylinder block.
Remove the RH cylinder block drain plug to drain the right bank
and the oil cooler hose to drain the left bank as shown.
5. Remove the reservoir tank to drain the engine coolant, then clean the reservoir tank before installing it.
6. Check the drained coolant for contaminants such as rust, corrosion or discoloration.
If the coolant is contaminated, flush the engine cooling system. Refer to MA-14, "
FLUSHING COOLING
SYSTEM" .
REFILLING ENGINE COOLANT
1. Close the radiator drain plug. Install the reservoir tank, cylinder block drain plug, and the oil cooler hose, if
removed for a total system drain or for engine removal or repair.

The radiator must be completely empty of coolant and water.

Apply sealant to the threads of the cylinder block drain plug. Use Genuine High Performance Thread
Sealant or equivalent. Refer to GI-45, "
RECOMMENDED CHEMICAL PRODUCTS AND SEALANTS" .
2. Set the vehicle heater controls to the full HOT and heater ON position. Turn the vehicle ignition ON with
the engine OFF as necessary to activate the heater mode.
3. Remove the vented reservoir cap and replace it with a non-vented reservoir cap before filling the cooling
system.
WBIA0391E
PBIC0146E
WBIA0392E
Radiator drain plug : Refer to CO-10, "RADIATOR" .
RH cylinder block drain plug : Refer to EM-73, "
CYLINDER BLOCK" .

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POWER SUPPLY, GROUND & CIRCUIT ELEMENTS
K ELECTRICAL
CONTENTS
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Revision: August 20072004 QX56 PRECAUTIONS .......................................................... 3
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” .................................................................. 3
Wiring Diagrams and Trouble Diagnosis .................. 3
POWER SUPPLY ROUTING CIRCUIT ...................... 4
Schematic ................................................................ 4
Wiring Diagram — POWER — ................................. 6
BATTERY POWER SUPPLY — IGNITION SW.
IN ANY POSITION ................................................ 6
ACCESSORY POWER SUPPLY — IGNITION
SW. IN ACC OR ON .............................................11
IGNITION POWER SUPPLY — IGNITION SW.
IN ON .................................................................. 12
IGNITION POWER SUPPLY — IGNITION SW.
IN ON AND/OR START ....................................... 13
IPDM E/R (INTELLIGENT POWER DISTRIBUTION
MODULE ENGINE ROOM) ...................................... 17
System Description ................................................ 17
SYSTEMS CONTROLLED BY IPDM E/R ........... 17
CAN COMMUNICATION LINE CONTROL ......... 17
IPDM E/R STATUS CONTROL ........................... 18
CAN Communication System Description .............. 18
Function of Detecting Ignition Relay Malfunction ... 18
CONSULT-II Function (IPDM E/R) ......................... 19
CONSULT-II BASIC OPERATION ...................... 19
SELF-DIAGNOSTIC RESULTS .......................... 20
DATA MONITOR ................................................. 20
ACTIVE TEST ..................................................... 22
Auto Active Test ..................................................... 23
DESCRIPTION .................................................... 23
OPERATION PROCEDURE ............................... 23
INSPECTION IN AUTO ACTIVE TEST MODE ... 23
Schematic .............................................................. 25
IPDM E/R Terminal Arrangement ........................... 26
IPDM E/R Power/Ground Circuit Inspection .......... 27
Inspection with CONSULT-II (Self-Diagnosis) ........ 28
Removal and Installation of IPDM E/R ................... 29
REMOVAL ........................................................... 29
INSTALLATION ................................................... 29GROUND CIRCUIT ................................................... 30
Ground Distribution ................................................. 30
MAIN HARNESS ................................................. 30
ENGINE ROOM HARNESS ................................ 33
ENGINE CONTROL HARNESS .......................... 36
BODY HARNESS ................................................ 37
BODY NO. 2 HARNESS ..................................... 38
BACK DOOR NO. 2 RH HARNESS .................... 39
HARNESS ................................................................. 40
Harness Layout ...................................................... 40
HOW TO READ HARNESS LAYOUT ................. 40
OUTLINE ............................................................. 41
MAIN HARNESS ................................................. 42
ENGINE ROOM HARNESS (LH VIEW) .............. 44
ENGINE ROOM HARNESS (RH VIEW) ............. 47
ENGINE CONTROL HARNESS .......................... 49
CHASSIS HARNESS .......................................... 51
BODY HARNESS ................................................ 53
BODY NO. 2 HARNESS ..................................... 55
ROOM LAMP HARNESS .................................... 57
FRONT DOOR LH HARNESS ............................ 58
FRONT DOOR RH HARNESS ............................ 58
REAR DOOR LH HARNESS ............................... 59
REAR DOOR RH HARNESS .............................. 59
BACK DOOR HARNESS .................................... 60
Wiring Diagram Codes (Cell Codes) ...................... 61
ELECTRICAL UNITS LOCATION ............................ 64
Electrical Units Location ......................................... 64
ENGINE COMPARTMENT .................................. 64
PASSENGER COMPARTMENT ......................... 65
Fuse ........................................................................ 67
Fusible Link ............................................................ 67
Circuit Breaker (Built Into BCM) ............................. 67
HARNESS CONNECTOR ......................................... 68
Description .............................................................. 68
HARNESS CONNECTOR (TAB-LOCKING
TYPE) .................................................................. 68
HARNESS CONNECTOR (SLIDE-LOCKING
TYPE) .................................................................. 69
HARNESS CONNECTOR (DIRECT-CONNECT

IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
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IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
PFP:284B7
System DescriptionEKS007NN

IPDM E/R (Intelligent Power Distribution Module Engine Room) integrates the relay box and fuse block
which were originally placed in engine compartment. It controls integrated relays via IPDM E/R control cir-
cuits.

IPDM E/R-integrated control circuits perform ON-OFF operation of relays, CAN communication control,
etc.

It controls operation of each electrical component via ECM, BCM and CAN communication lines.
CAUTION:
None of the IPDM E/R integrated relays can be removed.
SYSTEMS CONTROLLED BY IPDM E/R
1. Lamp control
Using CAN communication lines, it receives signals from the BCM and controls the following lamps:

Headlamps (Hi, Lo)

Parking lamps

Tail lamps

Front fog lamps
2. Wiper control
Using CAN communication lines, it receives signals from the BCM and controls the front wipers.
3. Rear window defogger relay control
Using CAN communication lines, it receives signals from the BCM and controls the rear window defogger
relay.
4. A/C compressor control
Using CAN communication lines, it receives signals from the ECM and controls the A/C compressor
(magnetic clutch).
5. Starter control
Using CAN communication lines, it receives signals from the ECM and controls the starter relay.
6. Cooling fan control
Using CAN communication lines, it receives signals from the ECM and controls the cooling fan relays.
7. Horn control
Using CAN communication lines, it receives signals from the BCM and controls the horn relay.
CAN COMMUNICATION LINE CONTROL
With CAN communication, by connecting each control unit using two communication lines (CAN L-line, CAN
H-line), it is possible to transmit a maximum amount of information with minimum wiring. Each control unit can
transmit and receive data, and reads necessary information only.
1. Fail-safe control

When CAN communication with other control units is impossible, IPDM E/R performs fail-safe control.
After CAN communication returns to normal operation, it also returns to normal control.

Operation of control parts by IPDM E/R during fail-safe mode is as follows:
Controlled system Fail-safe mode
Headlamp

With the ignition switch ON, the headlamp (low) is ON.

With the ignition switch OFF, the headlamp (low) is OFF.
Tail and parking lamps

With the ignition switch ON, the tail and parking lamps are ON.

With the ignition switch OFF, the tail and parking lamps are OFF.
Cooling fan

With the ignition switch ON, the cooling fan HI operates.

With the ignition switch OFF, the cooling fan stops.
Front wiperUntil the ignition switch is turned off, the front wiper LO and HI remains in the same status it
was in just before fail−safe control was initiated.
Rear window defogger Rear window defogger relay OFF

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IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
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IPDM E/R STATUS CONTROL
In order to save power, IPDM E/R switches status automatically based on each operating condition.
1. CAN communication status

CAN communication is normally performed with other control units.

Individual unit control by IPDM E/R is normally performed.

When sleep request signal is received from BCM, mode is switched to sleep waiting status.
2. Sleep waiting status

Process to stop CAN communication is activated.

All systems controlled by IPDM E/R are stopped. When 1 second has elapsed after CAN communica-
tion with other control units is stopped, mode switches to sleep status.
3. Sleep status

IPDM E/R operates in low current-consumption mode.

CAN communication is stopped.

When a change in CAN communication signal is detected, mode switches to CAN communication sta-
tus.

When a change in ignition switch signal is detected, mode switches to CAN communication status.
CAN Communication System DescriptionEKS007NO
Refer to LAN-5, "CAN COMMUNICATION" .
Function of Detecting Ignition Relay MalfunctionEKS007NP

When the integrated ignition relay is stuck in a "closed contact" position and cannot be turned OFF, IPDM
E/R turns ON tail and parking lamps for 10 minutes to indicate IPDM E/R malfunction.

When the state of the integrated ignition relay does not agree with the state of the ignition switch signal
received via CAN communication, the IPDM E/R activates the tail lamp relay.
NOTE:
When the ignition switch is turned ON, the tail lamps are OFF.
A/C compressor A/C compressor OFF
Front fog lamps Front fog lamp relay OFFControlled system Fail-safe mode
Ignition switch signal Ignition relay status Tail lamp relay
ON ON —
OFF OFF —
ON OFF —
OFF ON ON (10 minutes)

IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
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CONSULT-II Function (IPDM E/R)EKS007NQ
CONSULT-II can display each diagnostic item using the diagnostic test modes shown following.
CONSULT-II BASIC OPERATION
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. With the ignition switch OFF, connect CONSULT-II and CON-
SULT-II CONVERTER to the data link connector, then turn igni-
tion switch ON.
2. Touch “START (NISSAN BASED VHCL)”.
3. Touch “IPDM E/R” on “SELECT SYSTEM” screen.

If “IPDM E/R” is not displayed, print "SELECT SYSTEM"
screen, then refer to GI-39, "
CONSULT-II Data Link Connec-
tor (DLC) Circuit" .
IPDM E/R diagnostic mode Description
SELF-DIAG RESULTS Displays IPDM E/R self-diagnosis results.
DATA MONITOR Displays IPDM E/R input/output data in real time.
CAN DIAG SUPPORT MNTR The result of transmit/receive diagnosis of CAN communication can be read.
ACTIVE TEST Operation of electrical loads can be checked by sending drive signal to them.
BBIA0369E
BCIA0029E
BCIA0030E

PG-24
IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
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Concept of Auto Active Test

IPDM E/R actuates auto active test mode when it receives door switch signal from BCM via CAN commu-
nication line. Therefore, when auto active test mode is activated successfully, CAN communication
between IPDM E/R and BCM is normal.

If any of the systems controlled by IPDM E/R cannot be operated, possible cause can be easily diagnosed
using auto active test.
Diagnosis chart in auto active test mode
Symptom Inspection contents Possible cause
Rear window defogger
does not operate.Perform auto active
test. Does rear win-
dow defogger oper-
ate?YES

BCM signal input circuit
NO

Rear window defogger relay

Open circuit of rear window defogger

IPDM E/R malfunction

Harness or connector malfunction between IPDM E/R and rear window
defogger
Any of front wipers, tail
and parking lamps, front
fog lamps, and head-
lamps (Hi, Lo) do not
operate.Perform auto active
test. Does system in
question operate?YES

BCM signal input system
NO

Lamp/wiper motor malfunction

Lamp/wiper motor ground circuit malfunction

Harness/connector malfunction between IPDM E/R and system in
question

IPDM E/R (integrated relay) malfunction
A/C compressor does
not operate.Perform auto active
test. Does magnet
clutch operate?YES

BCM signal input circuit

CAN communication signal between BCM and ECM

CAN communication signal between ECM and IPDM E/R
NO

Magnet clutch malfunction

Harness/connector malfunction between IPDM E/R and magnet clutch

IPDM E/R (integrated relay) malfunction
Cooling fan does not
operate.Perform auto active
test. Does cooling fan
operate?YES

ECM signal input circuit

CAN communication signal between ECM and IPDM E/R
NO

Cooling fan motor malfunction

Harness/connector malfunction between IPDM E/R and cooling fan
motor

IPDM E/R (integrated relay) malfunction

PG-28
IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM)
Revision: August 20072004 QX56
Inspection with CONSULT-II (Self-Diagnosis)EKS007NV
CAUTION:
If a CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on which control unit(s) carry out CAN communication.
1. SELF-DIAGNOSIS RESULT CHECK
1. Connect CONSULT-II and select "IPDM E/R" on the Diagnosis System Selection screen.
2. Select "SELF-DIAG RESULTS" on the diagnosis mode selection screen.
3. Check display content in self-diagnosis results.
NOTE:
The Details for Display for the Period are as follows:

CRNT: Error currently detected by IPDM E/R.

PAST: Error detected in the past and stored in IPDM E/R memory.
Contents displayed
NO DTC DETECTED. FURTHER TESTING MAY BE REQUIRED.>>Inspection End.
CAN COMM CIRC>>Print out the self-diagnosis result and refer to LAN-5, "
CAN COMMUNICATION" .
CONSULT-II DisplayCONSULT-II
display codeTIME
Details of diagnosis result
CRNT PAST
NO DTC IS DETECTED.
FURTHER TESTING MAY BE REQUIRED.— — — No malfunction
CAN COMM CIRC U1000 X XAny of items listed below have errors:

TRANSMIT DIAG

ECM

BCM/SEC

HARNESS
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Wiring Diagram Codes (Cell Codes)EKS007NZ
Use the chart below to find out what each wiring diagram code stands for.
Refer to the wiring diagram code in the alphabetical index to find the location (page number) of each wiring
diagram.
Code Section Wiring Diagram Name
A/C,A ATC Auto Air Conditioner
A/SUSP RSU Rear Air Suspension
AF1B1 EC Air Fuel Ratio Sensor 1 (Bank 1)
AF1B2 EC Air Fuel Ratio Sensor 1 (Bank 2)
AF1HB1 EC Air Fuel Ratio Sensor 1 (Bank 1)
AF1HB2 EC Air Fuel Ratio Sensor 1 (Bank 2)
APPS1 EC Accelerator Pedal Position Sensor
APPS2 EC Accelerator Pedal Position Sensor
APPS3 EC Accelerator Pedal Position Sensor
ASC/BS EC ASCD Brake Switch
ASC/SW EC ASCD Steering Switch
ASCBOF EC ASCD Brake Switch
ASCIND EC ASCD Indicator
A/T AT A/T Assembly
AT/IND DI A/T Indicator Lamp
AUDIO AV Audio
AUTO/DP SE Automatic Drive Positioner
AUTO/L LT Auto Light Control
B/CLOS BL Back Door Auto Closure System
BACK/L LT Back-up Lamp
BRK/SW EC Brake Switch
CAN EC CAN Communication Line
CAN LAN CAN System
CHARGE SC Charging System
CHIME DI Warning Chime
CLOCK DI Clock
COMBSW LT Combination Switch
COMM AV Audio Visual Communication System
COMPAS DI Compass and Thermometer
COOL/F EC Cooling Fan Control
D/LOCK BL Power Door Lock
DEF GW Rear Window Defogger
DTRL LT Headlamp - With Daytime Light System
DVD AV DVD Entertainment System
ECM/PW EC ECM Power Supply for Back-Up
ECTS EC Engine Coolant Temperature Sensor
ETC1 EC Electric Throttle Control Function
ETC2 EC Throttle Control Motor Relay
ETC3 EC Throttle Control Motor
F/FOG LT Front Fog Lamp
F/PUMP EC Fuel Pump
FTTS EC Fuel Tank Temperature Sensor
FUELB1 EC Fuel Injection System Bank 1
FUELB2 EC Fuel Injection System Bank 2
H/AIM LT Headlamp Aiming Control
H/LAMP LT Headlamp
HORN WW Horn

RSU-12
TROUBLE DIAGNOSIS
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Basic InspectionEES00116
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 TimingEES00117
X: ON
—: OFF
Control Unit Input/Output Signal StandardEES00118
( ): 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

RSU-14
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
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 LEVEL-
IZER", “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.