Infiniti FX35 / FX45. Manual - part 757

SYSTEM DESCRIPTION

LAN-5

< SERVICE INFORMATION >

[CAN FUNDAMENTAL]

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CAN COMMUNICATION CONTROL CIRCUIT

*: These are the only control units wired with both ends of CAN communication system.

Diag on CAN

INFOID:0000000001451947

DESCRIPTION

“Diag on CAN” is a diagnosis using CAN communication instead of previous DDL1 and DDL2 communication
lines, between control units and diagnosis unit.

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.

LAN-6

< SERVICE INFORMATION >

[CAN FUNDAMENTAL]

SYSTEM DESCRIPTION

System Diagram

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.

TROUBLE DIAGNOSIS

LAN-7

< SERVICE INFORMATION >

[CAN FUNDAMENTAL]

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TROUBLE DIAGNOSIS

Condition of Error Detection

INFOID:0000000001451948

“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, 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

• 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.
NOTE:
CAN communication system is normal if “U1000” or “U1001” 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 System

INFOID:0000000001451949

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-37, "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.

LAN-8

< 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

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 name

Symptom

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.