control unit INFINITI M35 2007 Factory Service Manual

LAN-4
[CAN FUNDAMENTAL]
SYSTEM DESCRIPTION
Revision: 2007 April2007 M35/M45
SYSTEM DESCRIPTIONPFP:00000
CAN Communication SystemNKS004HA

CAN communication is a multiplex communication system. This enables the system to transmit and
receive large quantities of data at high speed by connecting control units with two communication lines
(CAN-H and CAN-L).

Control units on the CAN network transmit signals using the CAN communication control circuit. They
receive only necessary signals from other control units to operate various functions.

CAN communication lines adopt twisted-pair line style (two lines twisted) for noise immunity.
SYSTEM DIAGRAM
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" .

SYSTEM DESCRIPTION
LAN-5
[CAN FUNDAMENTAL]
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LAN
Revision: 2007 April2007 M35/M45
CAN COMMUNICATION CONTROL CIRCUIT
*: 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 ICIt converts digital signal into CAN communication signal, and CAN communication signal into digi-
tal signal.
Noise filter It eliminates noise of CAN communication signal.
Termination circuit
*
(Resistance of approx. 120 Ω)It produces potential difference.

LAN-6
[CAN FUNDAMENTAL]
SYSTEM DESCRIPTION
Revision: 2007 April2007 M35/M45
Diag on CANNKS004HB
DESCRIPTION
“Diag on CAN” is a diagnosis using CAN communication instead of previous DDL1 and DDL2 communication
lines, between control units and diagnosis unit.
SYSTEM DIAGRAM
SKIB8714E
Name Harness Description
DDL1Tx
RxIt 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 CANCAN-H
CAN-LIt is used for trouble diagnosis and control.

TROUBLE DIAGNOSIS
LAN-7
[CAN FUNDAMENTAL]
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Revision: 2007 April2007 M35/M45
TROUBLE DIAGNOSISPFP:00004
Condition of Error DetectionNKS004HC
“U1000” or “U1001” is indicated on SELF-DIAG RESULTS on CONSULT-II 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, between 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 EVEN THOUGH CAN COMMUNICATION SYSTEM
IS NORMAL

CONSULT-II CONVERTER not connected: Error may be detected by the self-diagnosis when not using
CONSULT-II CONVERTER (Depending on the control unit which carries out CAN communication).

Removal/installation of parts: Error may be detected 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 communica-
tion, 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 “U1001” is indicated on SELF-DIAG RESULTS of CON-
SULT-II under the above conditions. Erase the memory of the self-diagnosis of each unit.

LAN-8
[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
Symptom When Error Occurs in CAN Communication SystemNKS004HD
In CAN communication system, multiple units mutually transmit and receive signals. Each unit cannot transmit
and receive signals if any error occurs on CAN communication 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-41, "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.
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.

TROUBLE DIAGNOSIS
LAN-9
[CAN FUNDAMENTAL]
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Revision: 2007 April2007 M35/M45
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, 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 dif-
fer depending on the case. See below chart for the differences.
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 cir-
cuit
All Diag on CAN units are not
indicated.Normal operation.
CAN-H, CAN-L harness short-circuitMost of the units which are connected to the CAN
communication system enter fail-safe mode or are
deactivated.

LAN-10
[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
Example: Main Line Between Data Link Connector and ABS Actuator and Electric Unit (Con-
trol Unit) Open 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
wiper 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.

TROUBLE DIAGNOSIS
LAN-11
[CAN FUNDAMENTAL]
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Revision: 2007 April2007 M35/M45
Example: CAN-H, CAN-L Harness Short Circuit
SKIB8741E
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/RWhen the ignition switch is ON,

The headlamps (Lo) turn ON.

The cooling fan continues to rotate.

LAN-12
[CAN FUNDAMENTAL]
TROUBLE DIAGNOSIS
Revision: 2007 April2007 M35/M45
Self-DiagnosisNKS004HE
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-15,
"TROUBLE DIAG-
NOSES WORK FLOW" . 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.
Refer to the applicable
section 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
LAN-13
[CAN FUNDAMENTAL]
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LAN
Revision: 2007 April2007 M35/M45
CAN Diagnostic Support MonitorNKS004HF
CONSULT-II and CAN diagnostic support monitor (on-board diagnosis function) are used for detecting root
cause.
MONITOR ITEM (CONSULT-II)
Example: CAN DIAG SUPPORT MNTR indication
Without PAST
With PAST
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)