Nissan Sentra B18 (2020-2025) Service Manual / Electrical & Power Control / Power Control System :: Power Distribution System / Dtc/circuit Diagnosis

Nissan Sentra B18 (2020-2025) Service Manual: Dtc/circuit Diagnosis

B2fac-12 Accessory Relay

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC No.	CONSULT screen items (Trouble diagnosis content)	DTC detection condition
B2FAC-12	Accessory relay (Accessory relay)	Diagnosis condition	When ignition switch is ON
		Signal (terminal)	Accessory relay-1 control signal (terminal #34)
		Threshold	16 V or more
		Diagnosis delay time	1 second or more

POSSIBLE CAUSE

Harness or connectors (accessory relay-1 control signal circuit is shorted to battery)
Accessory relay-1
BCM

FAIL-SAFE

—

Dtc Confirmation Procedure

DTC Confirmation Procedure

PERFORM DTC CONFIRMATION PROCEDURE
1. CONSULT
  1. Ignition switch ON.
  2. Ignition switch OFF and wait for 1 minute with the front door LH opened.
  3. Ignition switch ON.
  4. Select “Self Diagnostic Result” mode of “BCM”.
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.

Dtc Diagnosis Procedure

DTC Diagnosis Procedure

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL CIRCUIT (SHORT TO BATTERY)

Ignition switch OFF.
Disconnect accessory relay-1 connector and BCM connector.

Check voltage between BCM harness connector and ground.

+	-	Voltage (Approx.)
M84	34	Ground	0 V

Voltage

(Approx.)

BCM

Connector

Terminal

M84

Ground

0 V

Is the inspection result normal?

YES >>

GO TO 2.

NO >>

Repair or replace harness

CHECK ACCESSORY RELAY-1
1. Check accessory relay-1. Refer to Component Inspection.
Is the inspection result normal?
YES>>
Replace BCM. Refer to Removal and Installation.
NO>>
Replace accessory relay-1.

B2fac-14 Accessory Relay

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC No.	CONSULT screen items (Trouble diagnosis content)	DTC detection condition
B2FAC-14	Accessory relay (Accessory relay)	Diagnosis condition	When ignition switch is OFF (not auto ACC status)
		Signal (terminal)	Accessory relay-1 control signal (terminal #34)
		Threshold	0 V
		Diagnosis delay time	1 second or more

POSSIBLE CAUSE

Harness or connectors (accessory relay-1 control signal circuit is shorted to ground or open)
Accessory relay-1
BCM

FAIL-SAFE

—

Dtc Confirmation Procedure

DTC Confirmation Procedure

PERFORM DTC CONFIRMATION PROCEDURE
1. CONSULT
  1. Ignition switch ON.
  2. Ignition switch OFF and wait for 1 minute with the front door LH opened.
  3. Ignition switch ON.
  4. Select “Self Diagnostic Result” mode of “BCM”.
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.

Dtc Diagnosis Procedure

DTC Diagnosis Procedure

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL VOLTAGE

Ignition switch OFF.
Disconnect BCM connector.

Check voltage between BCM harness connector and ground.

+	-	Voltage (Approx.)
M84	34	Ground	Battery voltage

Voltage

(Approx.)

BCM

Connector

Terminal

M84

Ground

Battery voltage

Is the inspection result normal?

YES >>

Replace BCM. Refer to Removal and Installation.

NO >>

GO TO 2.

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL CIRCUIT (OPEN)

Disconnect accessory relay-1 connector.

Check continuity between BCM harness connector and accessory relay-1 harness connector.

BCM		Accessory relay-1		Continuity
Connector	Terminal	Connector	Terminal	Continuity
M84	34	J-5	1	Yes

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

Repair or replace harness.

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL CIRCUIT (SHORT TO GROUND)

Check continuity between BCM harness connector and ground.

BCM		—	Continuity
Connector	Terminal	—	Continuity
M84	34	Ground	No

Is the inspection result normal?

YES >>

GO TO 4.

NO >>

Repair or replace harness.

CHECK ACCESSORY RELAY-1
1. Check accessory relay-1. Refer to Component Inspection.
Is the inspection result normal?
YES >>
Inspection End.
NO >>
Replace accessory relay-1.

Push-Button Ignition Switch Circuit

Component Function Check

Component Function Check

CHECK FUNCTION

CONSULT

Ignition switch ON
Select “Push SW” in “Data Monitor” mode of “HANDS FREE MODULE”.
Check the push-button ignition switch signal under the following conditions:

Test item	Condition	Status
Push SW	Push-button ignition switch is pressed	On
Push SW	Push-button ignition switch is not pressed	Off

Is the indication normal?

YES>>

Push-button ignition switch circuit is normal.

NO>>

Refer to Diagnosis Procedure.

Diagnosis Procedure

Diagnosis Procedure

CHECK PUSH-BUTTON IGNITION SWITCH SIGNAL OUTPUT VOLTAGE

Ignition switch OFF.
Disconnect push-button ignition switch connector.

Check voltage between push-button ignition switch harness connector and ground.

+	-	Voltage (Approx.)
M25	8	Ground	Battery voltage

Voltage

(Approx.)

Push-button ignition switch

Connector

Terminal

M25

Ground

Battery voltage

Is the inspection result normal?

YES >>

GO TO 4.

NO >>

GO TO 2.

CHECK PUSH-BUTTON IGNITION SWITCH SIGNAL CIRCUIT (OPEN)

Disconnect Intelligent Key unit connector.

Check continuity between push-button ignition switch harness connector and Intelligent Key unit harness connector.

Push-button ignition switch		Intelligent Key unit		Continuity
Connector	Terminal	Connector	Terminal	Continuity
M25	8	M155	9	Yes

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

Repair the harness or connector.

CHECK PUSH-BUTTON IGNITION SWITCH SIGNAL CIRCUIT (SHORT TO GROUND)

Check continuity between push-button ignition switch harness connector and ground.

Push-button ignition switch		—	Continuity
Connector	Terminal	—	Continuity
M25	8	Ground	No

Is the inspection result normal?

YES >>

Replace Intelligent Key unit. Refer to Removal and Installation.

NO >>

Repair the harness or connector.

CHECK PUSH-BUTTON IGNITION SWITCH GROUND CIRCUIT

Check continuity between push-button ignition switch harness connector and ground.

Push-button ignition switch		—	Continuity
Connector	Terminal	—	Continuity
M25	4	Ground	Yes

Is the inspection result normal?

YES >>

GO TO 5.

NO >>

Repair the harness or connector.

CHECK PUSH-BUTTON IGNITION SWITCH
1. Check push-button ignition switch. Refer to Component Inspection.
Is the inspection result normal?
YES >>
Inspection End.
NO >>
Replace push-button ignition switch. Refer to Removal and Installation.

Component Inspection

Component Inspection

CHECK PUSH-BUTTON IGNITION SWITCH

Ignition switch OFF.
Disconnect push-button ignition switch connector.

Check continuity between push-button ignition switch terminals.

Push-button ignition switch		Condition	Continuity
Terminals		Condition	Continuity
4	8	Pressed	Yes
4	8	Not pressed	No

Is the inspection result normal?

YES>>

Inspection End.

NO>>

Replace push-button ignition switch. Refer to Removal and Installation.

Accessory Relay-1

Diagnosis Procedure

Diagnosis Procedure

CHECK ACCESSORY RELAY-1 POWER

Disconnect accessory relay-1 connector.

Check voltage between accessory relay-1 harness connector and ground.

Accessory relay-1	—	Voltage (Approx.)
J-5	2	Ground	Battery voltage
5

Accessory relay-1

—

Voltage

(Approx.)

Connector

Terminal

J-5

Ground

Battery voltage

Is the inspection result normal?

YES >>

GO TO 2.

NO >>

Repair or replace harness or connectors.

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL VOLTAGE

Connect accessory relay-1 connector.

Check voltage between BCM harness connector and ground.

+		—	Condition		Voltage (Approx.)
BCM
Connector	Terminal
M84	34	Ground	Ignition switch	OFF	Battery voltage
M84	34	Ground	Ignition switch	ON	0 V

Is the inspection result normal?

YES >>

GO TO 4

NO >>

GO TO 3.

CHECK ACCESSORY RELAY-1 CONTROL SIGNAL CIRCUIT

Ignition switch OFF.
Disconnect BCM connector and accessory relay-1 connector.

Check continuity between BCM harness connector and accessory relay-1 harness connector.

BCM		Accessory relay-1		Continuity
Connector	Terminal	Connector	Terminal	Continuity
M84	34	J-5	1	Yes

Check continuity between BCM harness connector and ground.

BCM		Ground	Continuity
Connector	Terminal
M84	34		No

Is the inspection result normal?

YES >>

Replace BCM. Refer to Removal and Installation.

NO >>

Repair or replace harness or connectors.

CHECK ACCESSORY RELAY-1
1. Check accessory relay-1. Refer to Component Inspection.
Is the inspection result normal?
YES >>
Refer to Intermittent Incident.
NO >>
Replace accessory relay-1.

Component Inspection

Component Inspection

CHECK ACCESSORY RELAY-1

Ignition switch OFF.
Disconnect accessory relay-1 connector.
Check continuity between accessory relay-1 terminals.

Accessory relay-1	Condition	Continuity
Terminals	Condition	Continuity
	12 V direct current supply between terminals and .	Yes
	No current supply	No

Is the inspection result normal?

YES >>

Inspection End.

NO >>

Replace accessory relay-1.

Power Supply and Ground Circuit

Ipdm E/r (intelligent Power Distribution Module Engine Room)

Diagnosis Procedure

Diagnosis Procedure

CHECK FUSE AND FUSIBLE LINKS

Check that the following IPDM E/R fuse or fusible links are not blown:

Terminal	Signal name	Fuse and fusible link No.	Capacity
1	Battery power supply	D	80 A
2		E	80 A
81		B	300 A
81		70	40 A

Is the fuse or fusible link blown?

YES >>

Replace the blown fuse or fusible link after repairing the affected circuit.

NO >>

GO TO 2.

CHECK POWER SUPPLY CIRCUIT

Ignition switch OFF.
Disconnect IPDM E/R connectors.

Check voltage between IPDM E/R harness connectors and ground.

IPDM E/R		—	Voltage (Approx.)
Connector	Terminal	—	Voltage (Approx.)
E42	1	Ground	Battery voltage
E42	2
F97	81

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

Repair harness or connectors.

CHECK GROUND CIRCUIT

Disconnect IPDM E/R connectors.
Check continuity between IPDM E/R harness connectors and ground.

IPDM E/R		—	Continuity
Connector	Terminal	—	Continuity
E47	12	Ground	Yes
E43	31
E45	47

Is the inspection result normal?

YES>>

Inspection End.

NO>>

Repair harness or connectors.

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