Nissan Sentra B18 (2020-2025) Service Manual: B2c21-23 Front Seat Belt Buckle Switch Lh

Nissan Sentra B18 (2020-2025) Service Manual / Restraints / Srs Air Bag Control System :: Dtc/circuit Diagnosis / Bcm / B2c21-23 Front Seat Belt Buckle Switch Lh

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC No.	CONSULT screen items (Trouble diagnosis content)	DTC Detection Condition
B2C21–23	Seat belt buckle switch LH (Seat belt buckle switch LH)	Diagnosis condition	When ignition switch is ON.
		Signal (terminal)	Front seat belt buckle switch LH signal (BCM connector terminal: 17)
		Threshold	When the ON/OFF change of front seat belt buckle switch LH cannot be detected even once when all the following conditions are satisfied 10 times. Engine running Nissan Sentra Vehicle speed: 3 km/h or more
		Diagnosis delay time	—

POSSIBLE CAUSE

Front seat belt buckle switch LH
Harness or connectors [front seat belt buckle switch LH circuit is open or shorted]

FAIL-SAFE

—

Dtc Confirmation Procedure

DTC Confirmation Procedure

PERFORM DTC CONFIRMATION PROCEDURE
1. CONSULT
  1. Start the engine.
  2. Front seat belt LH is fastened.
  3. Drive Nissan Sentra vehicle at a speed of 3 km/h or more
  4. Ignition switch OFF.
  5. Front seat belt LH is released.
  6. Repeat steps from 1 to 5 (total 10 times).
  7. Select “Self Diagnostic Result” mode of “BCM”.
  8. Check for DTC.
Is DTC detected?
YES >>
Refer to DTC Diagnosis Procedure.
NO >>
To check malfunction symptom before repair: Refer to Intermittent Incident.
NO >>
Confirmation after repair: Inspection End.

Diagnosis Procedure

Diagnosis Procedure

CHECK FRONT SEAT BELT BUCKLE SWITCH LH INPUT SIGNAL

Ignition switch OFF.

Check voltage between front seat belt buckle switch LH harness connector and ground.

(+)		(–)	Condition		Voltage (Approx.)
Front seat belt buckle switch LH
Connector	Terminal
B57	1	Ground	Front seat belt buckle switch LH	OFF (seat belt is released)	Battery voltage
B57	1	Ground	Front seat belt buckle switch LH	ON (seat belt is fastened)	0 V

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

GO TO 2.

CHECK FRONT SEAT BELT BUCKLE SWITCH LH CIRCUIT

Disconnect front seat belt buckle switch LH connector and BCM connector.

Check continuity between front seat belt buckle switch LH harness connector and BCM harness connector.

Front seat belt buckle switch LH		BCM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
B57	1	M84	17	Yes

Check continuity between front seat belt buckle switch LH harness connector and ground.

Front seat belt buckle switch LH		—	Continuity
Connector	Terminal	—	Continuity
B57	1	Ground	No

Is the inspection result normal?

YES >>

Replace BCM. Refer to Removal and Installation.

NO >>

Repair or replace harness.

CHECK FRONT SEAT BELT BUCKLE SWITCH LH GROUND CIRCUIT

Disconnect front seat belt buckle switch LH connector.

Check continuity between front seat belt buckle switch LH harness connector and ground.

Front seat belt buckle switch LH		—	Continuity
Connector	Terminal	—	Continuity
B57	2	Ground	Yes

Is the inspection result normal?

YES>>

GO TO 4.

NO>>

Repair or replace harness.

CHECK FRONT SEAT BELT BUCKLE SWITCH LH
1. Check front seat belt buckle switch LH. Refer to Component Inspection.
Is the inspection result normal?
YES >>
Inspection End.
NO >>
Replace front seat belt buckle switch LH. Refer to Removal and Installation.

Bcm

...

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