2009 INFINITI QX56 200

LAN
PRECAUTIONSLAN-3
< PRECAUTION > [CAN FUNDAMENTAL]
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PRECAUTION
PRECAUTIONS
Precaution for Trouble DiagnosisINFOID:0000000003776428
CAUTION:
• Never apply 7.0 V or more to the measurement terminal.
• Use a tester with open terminal voltage of 7.0 V or less.
• Turn the ignition switch OFF and disconnect th
e battery cable from the negative terminal when
checking the harness.
Precaution for Harness RepairINFOID:0000000003776429
• Solder the repaired area and wrap tape around the soldered area. NOTE:
A fray of twisted lines must be within 110 mm (4.33 in).
• Bypass connection is never allowed at the repaired area. NOTE:
Bypass connection may cause CAN communication error. The
spliced wire becomes separated and t he characteristics of twisted
line are lost.
• Replace the applicable harness as an assembly if error is detected on the shield lines of CAN communica- tion line.
SKIB8766E
SKIB8767E
Revision: December 20092009 QX56

LAN-4
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
CAN COMMUNICATION SYSTEM
FUNCTION DIAGNOSIS
CAN COMMUNICATION SYSTEM
System DescriptionINFOID:0000000003776430
• CAN communication is a multiplex communication system. This enables the system to transmit and receive
large quantities of data at high speed by connecting c ontrol units with two communication lines (CAN-H and
CAN-L).
• Control units on the CAN network transmit signals us ing the CAN communication control circuit. They
receive only necessary signals from other c ontrol units to operate various functions.
• CAN communication lines adopt twisted-pair line st yle (two lines twisted) for noise immunity.
System DiagramINFOID:0000000003776431
Each control unit passes an electric current to the termination circuits when transmitting CAN communication
signal. The termination circuits produce an electrical potential difference between CAN-H and CAN-L. CAN
communication system transmits and receives CAN communication signals by the potential difference.
SKIB8887E
Component Description
Main line CAN communication line between splices
Branch line CAN communication line between splice and a control unit
Splice A point connecting a branch line with a main line
Termination circuit Refer to LAN-5, "
CAN Communication Control Circuit".
Revision: December 20092009 QX56

LAN
CAN COMMUNICATION SYSTEMLAN-5
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
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CAN Communication Control CircuitINFOID:0000000003776432
*: These are the only control units wired with both ends of CAN communication system.
SKIB8713E
Component
System description
CAN controller It controls CAN communication signal transmission and reception, error detection, etc.
Transceiver IC It converts digital signal into CAN communication signal, and CAN communication signal into digital
signal.
Noise filter It eliminates noise of CAN communication signal.
Termination circuit
*
(Resistance of approx. 120 Ω) It produces potential difference.
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LAN-6
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
DIAG ON CAN
DIAG ON CAN
DescriptionINFOID:0000000003776433
“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:0000000003776434
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: December 20092009 QX56

LAN
TROUBLE DIAGNOSISLAN-7
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
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TROUBLE DIAGNOSIS
Condition of Error DetectionINFOID:0000000003776435
“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:0000000003776436
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.
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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.
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LAN
TROUBLE DIAGNOSISLAN-9
< FUNCTION DIAGNOSIS > [CAN FUNDAMENTAL]
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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
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LAN-10
< FUNCTION DIAGNOSIS >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Self-Diagnosis
INFOID:0000000003776437
CAN Diagnostic Support MonitorINFOID:0000000003776438
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: December 20092009 QX56