Nissan Pathfinder (2008 year). Manual - part 469

LAN

TROUBLE DIAGNOSIS

LAN-7

< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

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TROUBLE DIAGNOSIS

Condition of Error Detection

INFOID:0000000001348720

“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:0000000001348721

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-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.

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 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.

LAN

TROUBLE DIAGNOSIS

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[CAN FUNDAMENTAL]

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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

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< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

TROUBLE DIAGNOSIS

Self-Diagnosis

INFOID:0000000001348722

CAN Diagnostic Support Monitor

INFOID:0000000001348723

CONSULT-III and CAN diagnostic support monitor (on-board 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”.

LAN

TROUBLE DIAGNOSIS

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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

OK

OK

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)

LAN-12

< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

TROUBLE DIAGNOSIS

Example: Vehicle Display 

Item

Result 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)

LAN

DIAGNOSIS AND REPAIR WORKFLOW

LAN-13

< BASIC INSPECTION >

[CAN FUNDAMENTAL]

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BASIC INSPECTION

DIAGNOSIS AND REPAIR WORKFLOW

Information Needed for Trouble Diagnosis

INFOID:0000000001348724

CAN communication system performs trouble diagnosis with the following tools.

How to Use CAN Communication Signal Chart

INFOID:0000000001348725

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 symptom, and by checking transmission and reception unit.

Tool

Usage

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

LAN-14

< BASIC INSPECTION >

[CAN FUNDAMENTAL]

DIAGNOSIS AND REPAIR WORKFLOW

Trouble Diagnosis Flow Chart

INFOID:0000000001348726

Trouble Diagnosis Procedure

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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