2007 INFINITI QX56 engine

LAN-8
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Example: Data link connector branch line open circuit
NOTE:
• When data link connector branch line is open, transmission and reception of CAN communication signals is
not affected. Therefore, no symptoms occur. However, be sure to repair malfunctioning circuit.
• When data link connector branch line is open, the screen-display of the CONSULT-II “SELECT SYSTEM”
screen may be the same as when the CAN communication line has short-circuit. However, symptoms differ
depending on the case. See below chart for the differences.
Unit name Symptom
ECM Engine torque limiting is affected, and shift harshness increases.
BCM Reverse warning chime does not sound.
EPS control unit Normal operation.
Combination meter• Shift position indicator and OD OFF indicator turn OFF.
• Warning lamps turn ON.
ABS actuator and electric unit (control unit) Normal operation.
TCM No impact on operation.
IPDM E/R Normal operation.
SKIB8739E
Unit name Symptom
ECM
Normal operation. BCM
EPS control unit
Combination meter
ABS actuator and electric unit (control unit)
TCM
IPDM E/R
SELECT SYSTEM
(CONSULT-II)Difference of symptom
Data link connector branch line open circuit
All Diag on CAN units are not
indicated.Normal operation.
CAN-H, CAN-L harness short-circuitMost the units which are connected to the CAN com-
munication system enter fail-safe mode or are deac-
tivated.

TROUBLE DIAGNOSIS
LAN-9
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
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P Example: Main Line Between Data Link Connector and ABS Actuator and Electric Unit (Control Unit) Open Circuit
Example: CAN-H, CAN-L Harness Short Circuit
SKIB8740E
Unit name Symptom
ECM Engine torque limiting is affected, and shift harshness increases.
BCM• Reverse warning chime does not sound.
• The front wiper moves under continuous operation mode even though the front wip-
er switch being in the intermittent position.
EPS control unit The steering effort increases.
Combination meter• The shift position indicator and OD OFF indicator turn OFF.
• The speedometer is inoperative.
• The odo/trip meter stops.
ABS actuator and electric unit (control unit) Normal operation.
TCM No impact on operation.
IPDM E/RWhen the ignition switch is ON,
• The headlamps (Lo) turn ON.
• The cooling fan continues to rotate.
SKIB8741E

LAN-10
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Self-Diagnosis
INFOID:0000000003533613
CAN Diagnostic Support MonitorINFOID:0000000003533614
CONSULT-II and CAN diagnostic support monitor (on-board diagnosis function) are used for detecting root
cause.
MONITOR ITEM (CONSULT-II)
Unit name Symptom
ECM• Engine torque limiting is affected, and shift harshness increases.
• Engine speed drops.
BCM• Reverse warning chime does not sound.
• The front wiper moves under continuous operation mode even though the front
wiper switch being in the intermittent position.
• The room lamp does not turn ON.
• The engine does not start (if an error or malfunction occurs while turning the igni-
tion switch is OFF.)
• The steering lock does not release (if an error or malfunction occurs while turning
the ignition switch is OFF.)
EPS control unit The steering effort increases.
Combination meter• The tachometer and the speedometer do not move.
• Warning lamps turn ON.
• Indicator lamps do not turn ON.
ABS actuator and electric unit (control unit) Normal operation.
TCM No impact on operation.
IPDM E/RWhen the ignition switch is ON,
• The headlamps (Lo) turn ON.
• The cooling fan continues to rotate.
DTCSelf-diagnosis item
(CONSULT-II indication)DTC detection condition Inspection/Action
U1000 CAN COMM CIRCUITWhen ECM is not transmitting or receiving CAN
communication signal of OBD (emission-related
diagnosis) for 2 seconds or more.
Refer to LAN-13
. When a control unit (except for ECM) is not
transmitting or receiving CAN communication
signal for 2 seconds or more.
U1001 CAN COMM CIRCUITWhen ECM is not transmitting or receiving CAN
communication signal other than OBD (emis-
sion-related diagnosis) for 2 seconds or more.
U1002 SYSTEM COMMWhen a control unit is not transmitting or receiv-
ing CAN communication signal for 2 seconds or
less.Start the inspection. Re-
fer to the applicable sec-
tion of the indicated
control unit.
U1010 CONTROL UNIT [CAN]When an error is detected during the initial diag-
nosis for CAN controller of each control unit.Replace the control unit
indicating “U1010”.

LAN-22
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
• For a description of Diag on CAN, refer to LAN-5, "Diag on CAN".
2. CAN DIAG SUPPORT MNTR: Check each item on “CAN DIAG SUPPORT MNTR”. Draw a line on the
diagnosis sheet to indicate the error circuit.
a. Reception item of “ENGINE”: On “TCM”, “UNKWN” is indicated. This means ECM cannot receive the sig-
nal from TCM. Draw a line to indicate an error between ECM and TCM (line 2-a in the figure).
NOTE:
If “UNKWN” is indicated on “TRANSMIT DIAG”, then the control unit cannot transmit CAN communication
signal to each unit. Draw a line between the control unit and the splice.
b. Reception item of “ADAPTIVE LIGHT”: On “TCM”, “UNKWN” is indicated. This means AFS cannot
receive the signal from TCM. Draw a line to indicate an error between AFS and TCM (line 2-b in the fig-
ure).
SKIB8892E

TROUBLE DIAGNOSES WORK FLOW
LAN-29
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
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1. SELF-DIAG RESULTS: Inspect the control units indicating “U1000” or “U1001” on SELF-DIAG RESULTS.
2. CAN DIAG SUPPORT MNTR (with PAST): Check the CAN DIAG SUPPORT MNTR (with PAST) of units
indicating “U1000” or “U1001” on SELF-DIAG RESULTS. Draw a line on the diagnosis sheet to indicate
the possible error circuit.
NOTE:
For the details of each indication on CAN DIAG SUPPORT MNTR, refer to LAN-40, "
CAN Diagnostic Sup-
port Monitor".
a. Reception item of “ENGINE”: “VDC/TCS/ABS”, “3” is indicated in the “PAST”. This means ECM could not
receive the signal from ABS in the past. Draw a line between ECM and ABS (line 2-a in the figure).
SKIB8731E

LAN-32
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
b. The tachometer moved normally: This means that “Engine speed signal” could communicate normally
between ECM and M&A (4-b in the figure).
5. Fill out the diagnosis sheet based on information from step 4.
a. The ABS warning lamp turned ON and speedometer did not move: Assume that a possible cause is no
communication between M&A and ABS. Draw a line between M&A and ABS. (Line 5-a in the figure).
SKIB8895E

HOW TO USE THIS SECTION
LAN-37
< SERVICE INFORMATION >[CAN]
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HOW TO USE THIS SECTION
CautionINFOID:0000000003533620
• This section describes information peculiar to a vehicle, sheets for trouble diagnosis, and inspection proce-
dures.
• For trouble diagnosis procedure, refer to LAN-14, "
Trouble Diagnosis Procedure".
Abbreviation ListINFOID:0000000003533621
Abbreviations in CAN communication signal chart, and the diagnosis sheet are as per the following list.
Abbreviation Unit nameSELECT SYSTEM
(CONSULT-II)CAN DIAG SUPPORT MNTR
(CONSULT-II)
4WD Transfer control unit ALL MODE AWD/4WD AWD/4WD
A-BAG Air bag diagnosis sensor unit AIR BAG –
ABS ABS actuator and electric unit (control unit) ABS VDC/TCS/ABS
ADP Driver seat control unit AUTO DRIVE POS. –
BCM BCM BCM BCM/SEC
DISP Display control unit – DISPLAY
DLC Data link connector – –
ECM ECM ENGINE ECM
HVAC Front air control HVAC –
ICC ICC unit ICCICC
ICC/e4WD
IPDM-E IPDM E/R IPDM E/R IPDM E/R
LASER ICC sensor – ICC SENSOR
M&A Combination meter – METER/M&A
STRG Steering angle sensor – STRG
TCM A/T assembly A/T TCM

LAN-40
< SERVICE INFORMATION >[CAN]
TROUBLE DIAGNOSIS
TROUBLE DIAGNOSIS
CAN Diagnostic Support MonitorINFOID:0000000003533626
Use “CAN DIAG SUPPORT MNTR” for detecting the root cause.
MONITOR ITEM LIST (CONSULT-II)
ECM
0: Error at present, 1 – 39: Error in the past (Number means the number of times the ignition switch is turned OFF→ON)
*: 39 or higher number is fixed at 39 until the self-diagnosis result is erased.
TCM
NOTE:
Replace the unit when “NG” is indicated on the “INITIAL DIAG”.
ICC Unit
NOTE:
Replace the unit when “NG” is indicated on the “INITIAL DIAG”.
SELECT SYS-
TEMCAN DIAG SUP-
PORT MNTRDescriptionNormal Error
PRSNT PAST PRSNT PAST
ENGINETRANSMIT DIAG Signal transmission status
OKOK
or
1 – 39
*UNKWN 0 VDC/TCS/ABSSignal receiving status from the ABS actu-
ator and electric unit (control unit)
METER/M&ASignal receiving status from the combina-
tion meter
BCM/SEC Signal receiving status from the BCM
ICC Signal receiving status from the ICC unit
HVAC Not used even though indicated
TCM Signal receiving status from the TCM OKOK
or
1 – 39
*UNKWN 0
EPS Not used even though indicated
IPDM E/R Signal receiving status from the IPDM E/R OKOK
or
1 – 39
*UNKWN 0
e4WD Not used even though indicated
AWD/4WDSignal receiving status from the transfer
control unitOKOK
or
1 – 39
*UNKWN 0
SELECT SYS-
TEMCAN DIAG SUP-
PORT MNTRDescriptionNormal Error
PRSNT
A/TINITIAL DIAG Status of CAN controller
OKNG
TRANSMIT DIAG Signal transmission status
UNKWN ECM Signal receiving status from the ECM
VDC/TCS/ABSSignal receiving status from the ABS actuator and electric unit
(control unit)
METER/M&A Signal receiving status from the combination meter
ICC/e4WD Signal receiving status from the ICC unit
AWD/4WD Signal receiving status from the transfer control unit