• 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 the battery cable from the negative terminal when

checking the harness.

Precautions for Harness Repair

INFOID:0000000007544226

• 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 the 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: 2013 February

2012 MURANO

LAN-6

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

CAN COMMUNICATION SYSTEM

SYSTEM DESCRIPTION

CAN COMMUNICATION SYSTEM

System Description

INFOID:0000000007544227

• 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

INFOID:0000000007544228

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-7, "CAN Communication Control Circuit"

Revision: 2013 February

2012 MURANO

LAN

CAN COMMUNICATION SYSTEM

LAN-7

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

CAN Communication Control Circuit

INFOID:0000000007544229

*: 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.

Revision: 2013 February

2012 MURANO

LAN-8

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

DIAG ON CAN

DIAG ON CAN

Description

INFOID:0000000007544230

“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

INFOID:0000000007544231

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: 2013 February

2012 MURANO

LAN

TROUBLE DIAGNOSIS

LAN-9

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

TROUBLE DIAGNOSIS

Condition of Error Detection

INFOID:0000000007544232

DTC (e.g. U1000 and U1001) of CAN communication is indicated on SELF-DIAG RESULTS on CONSULT if a
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 DTC OF CAN COMMUNICATION IS INDICATED EVEN THOUGH CAN COMMUNICATION
SYSTEM IS NORMAL

• 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 communication,

malfunctions (Depending on the control unit which carries out CAN communication).

• Error may be detected if reprogramming is not completed normally.

CAUTION:

CAN communication system is normal if DTC of CAN communication is indicated on SELF-DIAG
RESULTS of CONSULT under the above conditions. Erase the memory of the self-diagnosis of each
unit.

Symptom When Error Occurs in CAN Communication System

INFOID:0000000007544233

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-20, "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: 2013 February

2012 MURANO

LAN-10

< SYSTEM DESCRIPTION >

[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.

• The model (all units on CAN communication system are Diag on CAN) cannot perform CAN diagnosis with

CONSULT if the following error occurs. The error is judged by the symptom.

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 name

Symptom

ECM

Normal operation.

BCM

EPS control unit

Combination meter

ABS actuator and electric unit (control unit)

TCM

IPDM E/R

Error

Difference of symptom

Data link connector branch line open circuit

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: 2013 February

2012 MURANO

LAN

TROUBLE DIAGNOSIS

LAN-11

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

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/R

When the ignition switch is ON,
• The headlamps (Lo) turn ON.
• The cooling fan continues to rotate.

SKIB8741E

Revision: 2013 February

2012 MURANO

LAN-12

< SYSTEM DESCRIPTION >

[CAN FUNDAMENTAL]

TROUBLE DIAGNOSIS

CAN Diagnosis with CONSULT

INFOID:0000000007544234

CAN diagnosis on CONSULT extracts the root cause by receiving the following information.
• Response to the system call
• Control unit diagnosis information
• Self-diagnosis
• CAN diagnostic support monitor

Self-Diagnosis

INFOID:0000000007544235

If communication signals cannot be transmitted or received among units communicating via CAN communica-
tion line, CAN communication-related DTC is displayed on the CONSULT “Self Diagnostic Result” screen.
NOTE:
The following table shows examples of CAN communication-related DTC. For other DTC, refer to the applica-
ble sections.

CAN Diagnostic Support Monitor

INFOID:0000000007544236

MONITOR ITEM (CONSULT)

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 indication)

DTC detection condition

Inspection/Action

U1000

CAN COMM CIRCUIT

ECM

When ECM is not transmitting or receiving CAN
communication signal of OBD (emission-relat-
ed diagnosis) for 2 seconds or more.

Start the inspection. Re-
fer to the applicable sec-
tion of the indicated
control unit.

Except
for ECM

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 communi-
cation signal other than OBD (emission-related diagnosis)
for 2 seconds or more.

U1002

SYSTEM COMM

When a control unit is not transmitting or receiving CAN
communication signal for 2 seconds or less.

U1010

CONTROL UNIT(CAN)

When an error is detected during the initial diagnosis for
CAN controller of each control unit.

Replace the control unit
indicating “U1010”.

Revision: 2013 February

2012 MURANO

Content .. 36 37 38 39 ..