service INFINITI QX56 2007 Factory Service Manual

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< 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
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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

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< 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”.

TROUBLE DIAGNOSIS
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Example: CAN DIAG SUPPORT MNTR indication
Without PAST
With PAST
MONITOR ITEM (ON-BOARD DIAGNOSIS)
NOTE:
• For some models, CAN communication diagnosis result is received from the vehicle monitor. (CONSULT-II
is not available.)
• Refer to LAN-40, "
CAN Diagnostic Support Monitor" for the details.
SKIB8742E
Item PRSNT Description
Initial diagnosisOK Normal at present
NG Control unit error (Except for some control units)
Transmission diagnosisOK Normal at present
UNKWNUnable to transmit signals for 2 seconds or more.
Diagnosis not performed
Control unit name
(Reception diagnosis)OK Normal at present
UNKWNUnable to receive signals for 2 seconds or more.
Diagnosis not performed
No control unit for receiving signals. (No applicable optional parts)
Item PRSNT PAST Description
Transmission diagnosisOKOK Normal at present and in the past
1 – 39Normal at present, but unable to transmit signals for 2 seconds or more
in the past. (The number indicates the number of ignition switch cycles
from OFF to ON.)
UNKWN 0 Unable to transmit signals for 2 seconds or more at present.
Control unit name
(Reception diagnosis)OKOK Normal at present and in the past
1 – 39Normal at present, but unable to receive signals for 2 seconds or more
in the past. (The number indicates the number of ignition switch cycles
from OFF to ON.)
UNKWN 0 Unable to receive signals for 2 seconds or more at present
––Diagnosis not performed.
No control unit for receiving signals. (No applicable optional parts)

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< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Example: Vehicle Display
ItemResult indi-
catedError counter Description
CAN_COMM
(Initial diagnosis)OK 0 Normal at present
NG 1 – 50Control unit error
(The number indicates how many times diagnosis has been
run.)
CAN_CIRC_1
(Transmission diagnosis)OK 0 Normal at present
UNKWN 1 – 50Unable to transmit for 2 seconds or more at present.
(The number indicates how many times diagnosis has been
run.)
CAN_CIRC_2 – 9
(Reception diagnosis of each unit)OK 0 Normal at present
UNKWN 1 – 50Unable to transmit for 2 seconds or more at present.
(The number indicates how many times diagnosis has been
run.)
Diagnosis not performed.
No control unit for receiving signals. (No applicable optional
parts)

TROUBLE DIAGNOSES WORK FLOW
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< SERVICE INFORMATION >[CAN FUNDAMENTAL]
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TROUBLE DIAGNOSES WORK FLOW
Information Needed for Trouble DiagnosisINFOID:0000000003533615
CAN communication system performs trouble diagnosis with the following tools.
How to Use CAN Communication Signal ChartINFOID:0000000003533616
The CAN communication signal chart lists the signals needed for trouble diagnosis. It is useful for detecting
the root cause by finding a signal related to the symptom, and by checking transmission and reception unit.
To o l U s a g e
Interview sheet For filling in vehicle information and interview with customer.
Data sheet For attaching CONSULT-II data or on-board diagnosis data.
Diagnosis sheet For detecting the root cause. (Diagnosis sheet includes system diagram for every CAN system type)
SELECT SYSTEM
(CONSULT-II)
For checking the condition of control units and the status of CAN communication. SELF-DIAG RESULTS
(CONSULT-II)
CAN DIAG SUPPORT MNTR
(CONSULT-II)
CAN communication signal
chartFor converting information received from a customer into CAN communication signal transmission
and reception. This information can be used to judge whether a circuit between control units is nor-
mal or abnormal.
Abbreviation list For checking abbreviations in CAN communication signal chart and diagnosis sheet.
SKIB8715E

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< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
Trouble Diagnosis Flow Chart
INFOID:0000000003533617
Trouble Diagnosis ProcedureINFOID:0000000003533618
INTERVIEW WITH CUSTOMER
Interview with the customer is important to detect the root cause of CAN communication system errors and to
understand vehicle condition and symptoms for proper trouble diagnosis.
Points in interview• What: Parts name, system name
• When: Date, Frequency
• Where: Road condition, Place
• In what condition: Driving condition/environment
SKIB8716E

TROUBLE DIAGNOSES WORK FLOW
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• Result: Symptom
NOTE:
• Check normal units as well as error symptoms.
- Example: Circuit between ECM and the combination meter is judged normal if the customer indicates
tachometer functions normally.
• When a CAN communication system error is present, multiple control units may malfunction or go into fail-
safe mode.
• Indication of the combination meter is important to detect the root cause because it is the most obvious from
the customer, and it performs CAN communication with many units.
INSPECTION OF VEHICLE CONDITION
• Check whether or not “U1000” or “U1001” is indicated on “SELF-DIAG RESULTS” by CONSULT-II.
NOTE:
Root cause cannot be detected using the procedure in this section if “U1000” or “U1001” is not indicated.
• Check whether the symptom is reproduced or not.
NOTE:
• Never turn the ignition switch OFF or disconnect the battery cable while the reproducing the error. The
error may temporarily correct itself, making it difficult to determine the root cause.
• The procedures for present errors differ from the procedures for past errors. Refer to "DETECT THE
ROOT CAUSE".
CHECK OF CAN SYSTEM TYPE (HOW TO USE CAN SYSTEM TYPE SPECIFICATION CHART)
Determine CAN system type based on vehicle equipment. Then choose the correct diagnosis sheet.
NOTE:
There are two styles for CAN system type specification charts. Depending on the number of available system
types, either style A or style B may be used.
CAN System Type Specification Chart (Style A)
NOTE:
SKIB8717E

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< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
CAN system type is easily checked with the vehicle equipment identification information shown in the chart.
CAN System Type Specification Chart (Style B)
NOTE:
SKIB8888E

TROUBLE DIAGNOSES WORK FLOW
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CAN system type is easily checked with the vehicle equipment identification information shown in the chart.
CREATE INTERVIEW SHEET
Fill out the symptom described by the customer, vehicle condition, and CAN system type on the interview
sheet.
SKIB8889E