Infiniti G37 Coupe. Manual - part 1075

SBC-8

< FUNCTION DIAGNOSIS >

PRE-CRASH SEAT BELT SYSTEM

PRE-CRASH SEAT BELT SYSTEM

System Diagram

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System Description

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• Pre-crash seat belt has been adopted to RH/LH seat belts.
• When the pre-crash seat belt control unit judges the emergency braking operation, the motor built into the

pre-crash seat belt retract the shoulder belt to protect the passenger in case of collision, also give a sense of
security.

FUNCTION DESCRIPTION

Operation Condition

• Pre-crash seat belt operates under the following conditions.

Operation Prohibition Condition

• Pre-crash seat belt does not operate under the following conditions.

*

1

: When pre-crash seat belt does not operate after it continuously operates 3 times or more, operation can be performed again by stop-

ping operation for approximately 7 minutes.

*

2

: Refer to 

SBC-30, "Fail Safe"

 for details of fail-safe mode.

JMHIA0430GB

Condition

• During emergency brake operation
• When operation prohibition condition is not satisfied

Condition

• When seat belt is not fastened (Only the seat belt that is not fastened does not operate)
• When the vehicle speed is 15 km/h or less

• When pre-crash seat belt continuously operates 3 times or more *

1

• At fail-safe condition *

2

PRE-CRASH SEAT BELT SYSTEM

SBC-9

< FUNCTION DIAGNOSIS >

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 Refer to 

SBC-8, "System Description"

 for details of operation condition.

JMHIA0431GB

SBC-10

< FUNCTION DIAGNOSIS >

PRE-CRASH SEAT BELT SYSTEM

Component Parts Location

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Component Description

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1.

Battery

2.

30A (F/L-G)

3.

Pre-crash seat belt control unit

4.

Brake pedal stroke sensor

5.

Brake pedal

6.

Accelerator pedal

7.

Seat belt pre-tensioner

8.

Seat belt buckle

9.

Seat belt buckle switch

A.

Back side of glove box

B.

Back of driver instrument panel (low-
er)

C.

Brake pedal stroke sensor connector

D.

Back of center pillar lower garnish

E.

Seat belt pre-tensioner connector

JMHIA0432ZZ

Component

Function

Pre-crash seat belt control unit

It controls pre-crash seat belt motor according to input signal.

Pre-crash seat belt motor
(Seat belt motor [RH/LH])

It is built into seat belt retractor, and it pulls, returns, and maintains according to 
the motor rotation.

Brake pedal stroke sensor

• It changes voltage according to brake pedal depressed amount and sends the 

signal to pre-crash seat belt control unit.

• There are 2 signals (brake pedal stroke sensor 1 and 2) sent from the brake 

pedal stroke sensor. Pre-crash seat belt control unit will judge the stroke 
amount and the speed of the brake pedal according to the voltage of the signal 
sent by each side.

Seat belt buckle switch

It is arranged in the seat belt buckle and judges whether the seat belt is fastened 
or not fastened.

CAN system: Unified meter and A/C amp

It transmits the vehicle status to pre-crash seat belt control unit using the CAN 
communication system.

ON BOARD DIAGNOSTIC (OBD) SYSTEM

SBC-11

< FUNCTION DIAGNOSIS >

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ON BOARD DIAGNOSTIC (OBD) SYSTEM

Diagnosis Description

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HOW TO DIAGNOSE

• Diagnosis for pre-crash seat belt system can be performed using CONSULT-III electronic diagnostic tester.
• Diagnosis allows technicians to detect and analyze circuits that return errors.
• Diagnostic modes of CONSULT-III are.

DIAGNOSIS PROCEDURE

Follow the diagnosis procedure to check. Refer to 

SBC-3, "Work Flow"

.

DIAGNOSIS ITEM

• Communication
• LH/RH seat belt motor
• Brake pedal sensor
• Motor power supply
• Pre-crash seat belt control unit

ERASING SELF-DIAGNOSIS RESULTS

• SELF-DIAGNOSIS RESULTS

Current “SELF-DIAG RESULTS” are displayed. (If all suspect circuits have been repaired, "NO DTC" is dis-
played.)

• SELF-DIAG RESULTS [MEMORY]

Resume trouble diagnosis item selection screen, confirm “SELF-DIAG RESULTS”, and then touch ERASE
MEMORY.

CONSULT-III Function

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“SELF-DIAG RESULTS”, “DATA MONITOR”, “CAN DIAG SUPPORT MNTR”, “C/U PART NO” of pre-crash
seat belt system can be checked by combining communications between CONSULT-III (data reception and
command transmission).

SELF-DIAGNOSIS RESULTS

Check self-diagnosis results. 

CAUTION:

When malfunctions are detected in several systems, including the CAN communication [U1000], trou-
bleshoot the CAN communication [U1000].

Self-diagnosis mode

Inspection

SELF-DIAGNOSIS 
RESULTS

×

×

DATA MONITOR

×

×

Part to be diagnosed

Inspection Item, Diagnosis 

Mode

Description

Refer to

Pre-crash seat belt

SELF-DIAGNOSIS RESULTS

• Displays names of freeze frame data and 

basic inspection stored in ECM.

• Displays data recorded when a malfunction 

is detected.

• Can print out the display.
• Erases DTCs recorded in memory.

SBC-11

DATA MONITOR

• Displays input data for pre-crash seat belt 

control unit in real time.

SBC-11

CAN DIAG SUPPORT MNTR

• Monitors communication status of CAN 

communication.

LAN-13

ECU PART NUMBER

• Displays pre-crash seat belt control unit 

part number.

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