Nissan Sentra B18 (2020-2025) Service Manual: P1572 Ascd Brake Switch

Nissan Sentra B18 (2020-2025) Service Manual / Engine / Work Procedure (After Replacing Electric Throttle Control Actuator) / Dtc/circuit Diagnosis / P1572 Ascd Brake Switch

Dtc Description

DTC Description

DTC DETECTION LOGIC

Note:

This self-diagnosis has the one trip detection logic. When malfunction A is detected, DTC is not stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed. 1st trip DTC is erased when ignition switch OFF. And even when malfunction A is detected in two consecutive trips, DTC is not stored in ECM memory.

DTC	CONSULT screen terms (Trouble diagnosis content)	DTC detection condition
P1572	ASCD BRAKE SW (ASCD brake switch)	Diagnosis condition	Nissan Sentra Vehicle speed: More than 30 km/h (19 MPH)
		Signal (terminal)	Brake pedal position switch signal
		Threshold	Brake pedal position switch signal is not sent to ECM for extremely long time
		Diagnosis delay time	—

POSSIBLE CAUSE

Harness or connectors
- Brake pedal position switch circuit is shorted.
Brake pedal position switch
Incorrect brake pedal position switch installation
ECM

FAIL-SAFE

Not applicable

Confirmation Procedure

Confirmation Procedure

CHECK DTC PRIORITY

If DTC P1572 is displayed with DTC P0605, perform the trouble diagnosis for DTC P0605.

Is applicable DTC detected?
YES >>
Perform diagnosis of applicable. Refer to DTC Description.
NO >>
GO TO 2.
PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Note:
Procedure for malfunction B is not described here. It takes extremely long time to complete procedure for malfunction B. By performing procedure for malfunction A, the incident that causes malfunction B can be detected.

Will CONSULT be used?
YES >>
GO TO 3.
NO >>
GO TO 5.

PERFORM DTC CONFIRMATION PROCEDURE-1

With CONSULT

Start the engine.
Select “DATA MONITOR” mode of “ENGINE” using CONSULT.
Press ASCD switch and make sure that CRUISE indicator is displayed in combination meter.

Drive the Nissan Sentra vehicle for at least 5 consecutive seconds as per the following conditions.

CAUTION:

Always drive Nissan Sentra vehicle at a safe speed.

Note:

This procedure may be conducted with the drive wheels lifted in the shop or by driving the Nissan Sentra vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.

Nissan Sentra Vehicle speed	More than 30 km/h (19 mph)
Selector lever	Except P or N position (CVT models) Except neutral position (M/T models)

Check DTC.

Is DTC detected?

YES >>

Refer to DTC Diagnosis Procedure.

NO >>

GO TO 4.

PERFORM DTC CONFIRMATION PROCEDURE-2

With CONSULT

Drive the Nissan Sentra vehicle and maintain the following condition for at least 5 seconds.

CAUTION:

Always drive Nissan Sentra vehicle at a safe speed.

Note:

This procedure may be conducted with the drive wheels lifted in the shop or by driving the Nissan Sentra vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.

Nissan Sentra Vehicle speed	More than 30 km/h (19 mph)
Selector lever	Except P or N position (CVT models) Except neutral position (M/T models)
Driving condition	Depress the brake pedal for more than five seconds so as not to come off from the above-mentioned Nissan Sentra vehicle speed.

Check DTC.

Is DTC detected?

YES >>

Refer to DTC Diagnosis Procedure.

NO-1 >>

To check malfunction symptom before repair: Refer to Intermittent Incident.

NO-2 >>

Confirmation after repair: INSPECTION END

PERFORM COMPONENT FUNCTION CHECK

Without CONSULT

Note:

Use component function check to check the overall function of brake pedal position switch circuit. During this check, a DTC might not be confirmed.

Turn ignition switch ON.

Check the voltage between ECM harness connector terminals as per the following conditions.

ECM			Condition		Voltage (Approx.)
Connector	+	–
Connector	Terminal
E16	150	162	Brake pedal	Slightly depressed	0 V
E16	150	162	Brake pedal	Fully released	Battery voltage

Is the inspection result normal?

YES-1 >>

To check malfunction symptom before repair: Refer to Intermittent Incident.

YES-2 >>

Confirmation after repair: INSPECTION END

NO >>

Refer to DTC Diagnosis Procedure.

Dtc Diagnosis Procedure

DTC Diagnosis Procedure

CHECK DTC PRIORITY

If DTC P1572 is displayed with DTC P0605, perform the trouble diagnosis for DTC P0605.

Is applicable DTC detected?
YES >>
Perform diagnosis of applicable. Refer to DTC Description.
NO >>
GO TO 2.

CHECK BRAKE PEDAL POSITION SWITCH CIRCUIT

With CONSULT

Turn ignition switch ON.
Select “BRAKE SW1” in “DATA MONITOR” mode of “ENGINE” using CONSULT.

Check “BRAKE SW1” indication as per the following conditions.

Monitor item	Condition		Indication
BRAKE SW1	Brake pedal	Slightly depressed	OFF
BRAKE SW1	Brake pedal	Fully released	ON

Without CONSULT

Turn ignition switch ON.

Check the voltage between ECM harness connector terminals as per the following.

ECM			Condition		Voltage (Approx.)
Connector	+	–
	Terminal
E16	150	162	Brake pedal	Slightly depressed	0 V
				Fully released	Battery voltage

Is the inspection result normal?

YES >>

INSPECTION END

NO >>

GO TO 3.

CHECK BRAKE PEDAL POSITION SWITCH POWER SUPPLY CIRCUIT

Turn ignition switch OFF.
Disconnect brake pedal position switch harness connector.
Turn ignition switch ON.

Check the voltage between brake pedal position switch harness connector and ground.

+		−	Voltage
Brake pedal position switch
Connector	Terminal
E84	1	Ground	Battery voltage

Is the inspection result normal?

YES >>

GO TO 4.

NO >>

Perform the trouble diagnosis for power supply circuit.

CHECK BRAKE PEDAL POSITION SWITCH INPUT SIGNAL CIRCUIT

Disconnect ECM harness connector.

Check the continuity between brake pedal position switch harness connector and ECM harness connector.

Brake pedal position switch		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
E84	2	E16	150	Existed

Also check harness for short to ground and to power.

Is the inspection result normal?

YES >>

GO TO 5.

NO >>

Repair or replace malfunctioning part.

CHECK BRAKE PEDAL POSITION SWITCH

Check the brake pedal position switch. Refer to Component Inspection.

Is the inspection result normal?
YES >>
INSPECTION END
NO >>
Replace brake pedal position switch. Refer to Removal and Installation.

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