Nissan Sentra B18 (2020-2025) Service Manual: P1805 Brake Switch

Nissan Sentra B18 (2020-2025) Service Manual / Engine / Work Procedure (After Replacing Electric Throttle Control Actuator) / Dtc/circuit Diagnosis / P1805 Brake Switch

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC	CONSULT screen terms (Trouble diagnosis content)	DTC detection condition
P1805	BRAKE SW/CIRCUIT (Brake switch circuit)	Diagnosis condition	—
		Signal (terminal)	Brake pedal position switch signal
		Threshold	A brake pedal position switch signal is not sent to ECM while the Nissan Sentra vehicle is driving
		Diagnosis delay time	—

POSSIBLE CAUSE

Harness or connectors (Brake pedal position switch circuit is open or shorted.)
Brake pedal position switch

FAIL-SAFE

Engine Control System

Engine operating condition in fail-safe mode
Fail safe mode	Nissan Sentra Vehicle behavior
Others	ECM controls the electric throttle control actuator by regulating the throttle opening to a small range. Therefore, acceleration will be poor.
	Nissan Sentra Vehicle condition	Driving condition
	When engine is idling	Normal
	When accelerating	Poor acceleration

Idle Start/Stop System

When a DTC is detected, the start/stop indicator lamp blinks slowly and the idle start/stop system operation is prohibited.

When ECM detects error while operating the idle start/stop system, ECM restarts the engine.

Confirmation Procedure

Confirmation Procedure

PERFORM COMPONENT FUNCTION CHECK
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC. Refer to Diagnosis Description.
4. Check 1st trip DTC.
Is 1st trip 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

Dtc Diagnosis Procedure

DTC Diagnosis Procedure

CHECK BRAKE PEDAL POSITION SWITCH CIRCUIT

Turn ignition switch OFF.

Depress the brake pedal and check the stop lamp when releasing.

Brake pedal	Stop lamp
Fully released	Not illuminated
Slightly depressed	Illuminated

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

GO TO 2.

CHECK BRAKE PEDAL POSITION SWITCH POWER SUPPLY

Disconnect brake pedal position switch harness connector.

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 3.

NO >>

Perform the trouble diagnosis for power supply circuit.

CHECK BRAKE PEDAL POSITION SWITCH INPUT SIGNAL CIRCUIT

Disconnect brake pedal position switch harness connector.
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 4.

NO >>

Repair or replace malfunctioning part.

CHECK BRAKE PEDAL POSITION SWITCH

Check brake pedal position switch. Refer to Component Inspection.

Is the inspection result normal?
YES >>
INSPECTION END
NO >>
Replace brake pedal position switch. Refer to Exploded View.

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