INFINITI QX56 2008 Factory Service Manual

LAN-6
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
DIAG ON CAN
DIAG ON CAN
DescriptionINFOID:0000000001374964
“Diag on CAN” is a diagnosis using CAN communication instead of previous DDL1 and DDL2 communication
lines, between control units and diagnosis unit.
System DiagramINFOID:0000000001374965
SKIB8714E
Name
Harness Description
DDL1 Tx
Rx
It is used for trouble diagnosis. (CAN-H and CAN-L are used for controlling)
DDL2 K-LINE It is used for trouble diagnosis. (CAN-H and CAN-L are used for controlling)
Diag on CAN CAN-H
CAN-L It is used for trouble diagnosis and control.
Revision: March 2010
2008 QX56

LAN
TROUBLE DIAGNOSISLAN-7
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
C
D
E
F
G H
I
J
K L
B A
O P
N
TROUBLE DIAGNOSIS
Condition of Error DetectionINFOID:0000000001374966
“U1000” or “U1001” is indicated on SELF-DIAG RESULTS on CONSULT-III if CAN communication signal is
not transmitted or received between units for 2 seconds or more.
CAN COMMUNICATION SYSTEM ERROR
• CAN communication line open (CAN-H, CAN-L, or both)
• CAN communication line short (ground, betw
een CAN communication lines, other harnesses)
• Error of CAN communication control circuit of the unit connected to CAN communication line
WHEN “U1000” OR “U1001” IS INDICATED EV EN THOUGH CAN COMMUNICATION SYSTEM IS
NORMAL
• Removal/installation of parts: Error may be detec ted when removing and installing CAN communication unit
and related parts while turning the ignition switch ON. (A DTC except for CAN communication may be
detected.)
• Fuse blown out (removed): CAN communication of the unit may cease.
• Voltage drop: Error may be detected if voltage drops due to discharged battery when turning the ignition
switch ON (Depending on the control unit which carries out CAN communication).
• Error may be detected if the power supply circuit of the control unit, which carries out CAN communication,
malfunctions (Depending on the control unit which carries out CAN communication).
• Error may be detected if reprogramming is not completed normally.
NOTE:
CAN communication system is normal if “U1000” or “U 1001” is indicated on SELF-DIAG RESULTS of CON-
SULT-III under the above conditions. Erase the memory of the self-diagnosis of each unit.
Symptom When Error Occurs in CAN Communication SystemINFOID:0000000001374967
In CAN communication system, multiple units mutually transmit and receive signals. Each unit cannot transmit
and receive signals if any error occurs on CAN communicati on line. Under this condition, multiple control units
related to the root cause malfunction or go into fail-safe mode.
ERROR EXAMPLE
NOTE:
• Each vehicle differs in symptom of each unit under fail-safe mode and CAN communication line wiring.
• Refer to LAN-36, "
Abbreviation List" for the unit abbreviation.
Example: TCM branch line open circuit
SKIB8738E
Unit name Symptom
ECM Engine torque limiting is affected, and shift harshness increases.
BCM Reverse warning chime does not sound.
Revision: March 2010 2008 QX56

LAN-8
< FUNCTION DIAGNOSIS >[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
are not affected. Therefore, no symptoms occur. However, be sure to repair malfunctioning circuit.
• When data link connector branch line is open, “ECU list” displayed on the CONSULT-III “CAN DIAG SUP- PORT MNTR” may be the same as when the CAN communication line has short-circuit. However, symp-
toms differ depending on the case. See below chart for the differences.
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.
Unit name
Symptom
SKIB8739E
Unit nameSymptom
ECM
Normal operation.
BCM
EPS control unit
Combination meter
ABS actuator and electric unit (control unit)
TCM
IPDM E/R
“ECU list” on the “CAN DIAG SUPPORT MNTR”(CONSULT-III) 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-circuit Most of the units which are connected to the CAN
communication system enter fail-safe mode or are
deactivated.
Revision: March 2010
2008 QX56

LAN
TROUBLE DIAGNOSISLAN-9
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
C
D
E
F
G H
I
J
K L
B A
O P
N
Example: Main Line Between Data Link Connector and ABS Actuator and Electr
ic 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/R When the ignition switch is ON,
• The headlamps (Lo) turn ON.
• The cooling fan continues to rotate.
SKIB8741E
Revision: March 2010
2008 QX56

LAN-10
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Self-Diagnosis
INFOID:0000000001374968
CAN Diagnostic Support MonitorINFOID:0000000001374969
CONSULT-III and CAN diagnostic support monitor (on-boar d diagnosis function) are used for detecting root
cause.
MONITOR ITEM (CONSULT-III)
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 OFF.)
• The steering lock does not release (if an error or malfunction occurs while turning the ignition switch 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/R When the ignition switch is ON,
• The headlamps (Lo) turn ON.
• The cooling fan continues to rotate.
DTC
Self-diagnosis item
(CONSULT-III indication) DTC detection condition
Inspection/Action
U1000 CAN COMM CIRCUIT When 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 CIRCUIT When ECM is not transmitting or receiving CAN
communication signal other than OBD (emis-
sion-related diagnosis) for 2 seconds or more.
U1002 SYSTEM COMM When 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”.
Revision: March 2010
2008 QX56

LAN
TROUBLE DIAGNOSISLAN-11
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
C
D
E
F
G H
I
J
K L
B A
O P
N
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-III is
not available.)
PKID1075E
Item PRSNT Description
Initial diagnosis OK Normal at present
NG Control unit error (Except for some control units)
Transmission diagnosis OK Normal at present
UNKWN Unable to transmit signals for 2 seconds or more.
Diagnosis not performed
Control unit name
(Reception diagnosis) OK Normal at present
UNKWN Unable 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 diagnosis OKOK Normal at present and in the past
1 – 39 Normal 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) OK
OK Normal at present and in the past
1 – 39 Normal 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)
Revision: March 2010
2008 QX56

LAN-12
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Example: Vehicle Display
ItemResult indi-
cated Error counter
Description
CAN_COMM
(Initial diagnosis) OK
0 Normal at present
NG 1 – 50 Control unit error
(The number indicates how many times diagnosis has been
run.)
CAN_CIRC_1
(Transmission diagnosis) OK
0 Normal at present
UNKWN 1 – 50 Unable 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 – 50 Unable 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)
Revision: March 2010
2008 QX56

LAN
DIAGNOSIS AND REPAIR WORKFLOWLAN-13
< BASIC INSPECTION > [CAN FUNDAMENTAL]
C
D
E
F
G H
I
J
K L
B A
O P
N
BASIC INSPECTION
DIAGNOSIS AND REPAIR WORKFLOW
Information Needed for Trouble DiagnosisINFOID:0000000001374970
CAN communication system performs trouble diagnosis with the following tools.
How to Use CAN Communication Signal ChartINFOID:0000000001374971
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 sy
mptom, 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 copying on-board diagnosis data.
Diagnosis sheet For detecting the root cause. (Diagnosis sheet includes system diagram for every CAN system type)
ECU list
(On the “CAN DIAG SUPPORT
MNTR”) For checking the condition of control units and the status of CAN communication.
SELF-DIAG RESULTS
(CONSULT-III)
CAN DIAG SUPPORT MNTR
(CONSULT-III)
CAN communication signal
chart For 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
Revision: March 2010 2008 QX56

LAN-14
< BASIC INSPECTION >[CAN FUNDAMENTAL]
DIAGNOSIS AND REPAIR WORKFLOW
Trouble Diagnosis Flow Chart
INFOID:0000000001374972
Trouble Diagnosis ProcedureINFOID:0000000001374973
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
PKID1210E
Revision: March 2010 2008 QX56

LAN
DIAGNOSIS AND REPAIR WORKFLOWLAN-15
< BASIC INSPECTION > [CAN FUNDAMENTAL]
C
D
E
F
G H
I
J
K L
B A
O P
N
• 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 to
the customer, and it performs CAN communication with many units.
INSPECTION OF VEHICLE CONDITION
• Check whether or not “U1000” or “U1001” is indi cated on “SELF-DIAG RESULTS” by CONSULT-III.
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:
• Do not turn the ignition switch OFF or disconnect the battery cable while 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 equipm ent. Then choose the correct diagnosis sheet.
NOTE:
There are two styles for CAN system type specificat ion 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
Revision: March 2010 2008 QX56