Infiniti G37 Coupe. Manual - part 835

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TROUBLE DIAGNOSIS

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< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

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CAN Diagnosis with CONSULT-III

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CAN diagnosis on CONSULT-III 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

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CAN Diagnostic Support Monitor

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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.

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

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.

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”.

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< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

TROUBLE DIAGNOSIS

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.

JSMIA0015GB

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)

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TROUBLE DIAGNOSIS

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< FUNCTION DIAGNOSIS >

[CAN FUNDAMENTAL]

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Example: Vehicle Display 

How to Use CAN Communication Signal Chart

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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.

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)

SKIB8715E

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< BASIC INSPECTION >

[CAN FUNDAMENTAL]

DIAGNOSIS AND REPAIR WORKFLOW

BASIC INSPECTION

DIAGNOSIS AND REPAIR WORKFLOW

Trouble Diagnosis Flow Chart

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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
• Result: Symptom
NOTE:
• Check normal units as well as error symptoms.
- Example: Circuit between ECM and the combination meter is judged normal if the customer indicates

tachometer functions normally.

• When a CAN communication system error is present, multiple control units may malfunction or go into fail-

safe mode.

JSMIA0016GB