Infiniti G37 Coupe. Manual - part 1078

SBC-20

< COMPONENT DIAGNOSIS >

B2454 MOTOR PWR SUP CIRC

B2454 MOTOR PWR SUP CIRC

Description

INFOID:0000000001711988

• When the control unit judges the emergency braking operation, it retracts the shoulder belt with the electric

motor and reduces the looseness of the belt.

• When the ignition switch is turned ON, the current is flowing to the seat belt motor. It stops when the ignition

switch is turned OFF.

• It is installed to back of center pillar garnish.

DTC Logic

INFOID:0000000001711989

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

CHECK MOTOR POWER SUPPLY CIRCUIT

Check “SELF-DIAG RESULT” of CONSULT

−

lll.

Is any DTC detected?

YES

>> Refer to 

SBC-20, "Diagnosis Procedure"

.

NO

>> Inspection End.

Diagnosis Procedure

INFOID:0000000001711990

1.

CHECK MOTOR POWER SUPPLY CIRCUIT

1.

Disconnect the pre-crash seat belt control unit connector.

2.

Check that voltage between pre-crash seat belt control unit harness connector terminal 2 and ground is
12V.

Is the inspection result normal?

YES

>> Inspection End.

NO

>> Repair or replace pre-crash seat belt control unit power supply circuit harness.

DTC No.

Self-diagnosis item

DTC Detection Condition

Possible causes

B2454

Motor power supply cir-
cuit system

Motor power supply circuit is open or shorted

CAUTION:

Malfunction is judged when 30A (F/L-G) fusible 
link blows out even if motor power supply cir-
cuit is not malfunctioning. 

• Open circuit and short circuit to 

ground in drive circuit power supply 
harness 

• ECU internal malfunction 

2 - Ground

Approx. 12V

B2455 PSB C/U INT CIRCUIT

SBC-21

< COMPONENT DIAGNOSIS >

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B2455 PSB C/U INT CIRCUIT

Description

INFOID:0000000001711991

• It controls pre-crash seat belt motor according to input signal.
• It consists of pre-crash seat belt control unit.
• It is installed on the back of the glove box.

DTC Logic

INFOID:0000000001711992

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

SELF-DIAGNOSIS WITH PRE-CRASH SEAT BELT CONTROL UNIT

Check “SELF-DIAG RESULT” of CONSULT

−

lll.

Is any DTC detected?

YES

>> Replace pre-crash seat belt control unit.

NO

>> Pre-crash seat belt control unit is normal.

DTC No.

Self-diagnosis item

DTC Detection Condition

Possible causes

B2455

C/U internal circuit 

system 

Pre-crash seat belt control unit internal circuit malfunction 

ECU internal malfunction 

SBC-22

< COMPONENT DIAGNOSIS >

BRAKE PEDAL STROKE SENSOR SHIELD WIRE CIRCUIT CHECK

BRAKE PEDAL STROKE SENSOR SHIELD WIRE CIRCUIT CHECK

Description

INFOID:0000000001711993

• It changes voltage according to brake pedal depressed amount and sends the signal to pre-crash seat belt

control unit.

• There are two 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.

• It is installed to back of driver instrument panel (lower).

Component Function Check

INFOID:0000000001711994

1.

CHECK PRE-CRASH SEAT BELT CONTROL UNIT INPUT SIGNAL

With CONSULT-III
When checking “B-pedal sensor SIG1” and “2” on DATA MONITOR screen, check that the voltage does not
change if brake pedal is not operated.
NOTE:
Diagnosis should be performed with engine running, audio and air conditioner operating.

Without CONSULT-III
1.

Start the engine.

2.

Check that voltage between pre-crash seat belt harness connector and ground without brake pedal oper-
ation is normal.

Is the inspection result normal?

YES

>> Brake pedal stroke sensor shield ground system is normal.

NO

>> Check shield wire for damage. Repair or replace if necessary.

B-pedal sensor SIG1

Brake released

There is no change in the voltage value, 
and it is almost constant

B-pedal sensor SIG2

Brake released

There is no change in the voltage value, 
and it is almost constant

Terminal

Measuring condition

Voltage

(+)

(-)

16

Ground

Brake released
When engine is started and 
audio and air conditioner are 
operating

There is no 
change in the 
voltage value, 
and it is almost 
constant.

20

SEAT BELT BUCKLE SWITCH (DRIVER SIDE) CIRCUIT CHECK

SBC-23

< COMPONENT DIAGNOSIS >

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SEAT BELT BUCKLE SWITCH (DRIVER SIDE) CIRCUIT CHECK

Description

INFOID:0000000001711999

• Perform the control of tension reducer according to the seat belt buckle switch ON/OFF.
• If the seat belt is not fastened when the ignition switch is turned ON, it detects whether the seat belt is fas-

tened or not so as to turn on the seat belt warning lamp of combination meter.

• The seat belt buckle switch is installed in the seat belt buckle.

Component Function Check

INFOID:0000000001712000

1.

CHECK PRE-CRASH SEAT BELT CONTROL UNIT INPUT SIGNAL

With CONSULT-III
When checking “BUCKLE SW LH” on DATA MONITOR screen, check that ON/OFF display changes synchro-
nized with the insertion operation to the seat belt buckle.

Without CONSULT-III
1.

Turn the ignition switch ON.

2.

Check that voltage between LH seat belt buckle switch harness connector terminal 1 and ground is nor-
mal.

Is the inspection result normal?

YES

>> LH seat belt buckle switch system is normal.

NO

>> GO TO 2.

2.

CHECK LH SEAT BELT BUCKLE SWITCH HARNESS

1.

Turn the ignition switch OFF.

2.

Disconnect pre-crash seat belt control unit connector and LH seat belt buckle switch connector.

3.

Does continuity between pre-crash seat belt control unit harness connector terminal 10 and LH seat belt
buckle switch harness connector terminal 1 exist?

4.

Does continuity between pre-crash seat belt control unit harness connector terminal 10 and ground exist?

Is the inspection result normal?

YES

>> Refer to 

SBC-23, "Component Inspection (Driver seat belt buckle switch)"

.

NO

>> Repair or replace harness between pre-crash seat belt control unit and LH seat belt buckle switch.

Component Inspection (Driver seat belt buckle switch)

INFOID:0000000001712001

1.

CHECK LH SEAT BELT BUCKLE SWITCH

Check that continuity between LH seat belt buckle switch terminals 1 and 2 is normal when performing the
insertion operation to the seat belt buckle.

BUCKLE SW LH

When LH seat belt is 
not fastened

OFF

When LH seat belt is 
fastened

ON

Terminal

Measuring condition

Voltage (V)

(+)

(-)

1

Ground

When seat belt is not fastened

Approx. 0

When seat belt is fastened

Approx. 12

10 - 1

Existed

10 - Ground

Not existed