Nissan Altima 2007-2012 Service Manual: P1805 Brake switch

Description

Brake switch signal is applied to the ECM via the stop lamp switch when the brake pedal is depressed. This signal is used mainly to decrease the engine speed when the vehicle is being driven.

DTC Logic

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.

2. Fully depress the brake pedal for at least 5 seconds.

3. Erase the DTC.

4. Check 1st trip DTC.

Is 1st trip DTC detected? YES >> Go to EC-1434, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK STOP LAMP SWITCH CIRCUIT

1. Turn ignition switch OFF.

2. Check the stop lamp when depressing and releasing the brake pedal.

Is the inspection result normal? YES >> GO TO 4.

NO >> GO TO 2.

2.CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT

1. Disconnect stop lamp switch harness connector.

2. Check the voltage between stop lamp switch harness connector and ground.

Is the inspection result normal? YES >> GO TO 4.

NO >> GO TO 3.

3.DETECT MALFUNCTIONING PART

Check the following.

• Fuse block (J/B) connector E6

• 10 A fuse (No. 7) • Harness for open or short between battery and stop lamp switch

>> Repair open circuit, short to ground or short to power in harness or connectors.

4.CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Disconnect stop lamp switch harness connector.

2. Disconnect ECM harness connector.

3. Check the continuity between stop lamp switch harness connector and ECM harness connector.

4. Also check harness for short to ground and short to power.

Is the inspection result normal? YES >> GO TO 6.

NO >> GO TO 5.

5.DETECT MALFUNCTIONING PART

Check the following.

• Fuse block (J/B) connector E6

• Harness for open or short between ECM and stop lamp switch

>> Repair open circuit, short to ground or short to power in harness or connectors.

6.CHECK STOP LAMP SWITCH

Refer to EC-1435, "Component Inspection (Stop Lamp Switch)".

Is the inspection result normal? YES >> GO TO 7.

NO >> Replace stop lamp switch.

7.CHECK INTERMITTENT INCIDENT

Refer to GI-42, "Intermittent Incident".

>> INSPECTION END

Component Inspection (Stop Lamp Switch)

1.CHECK STOP LAMP SWITCH-I

1. Turn ignition switch OFF.

2. Disconnect stop lamp switch harness connector.

3. Check harness continuity between stop lamp switch terminals under the following conditions.

Is the inspection result normal? YES >> INSPECTION END

NO >> GO TO 2.

2.CHECK STOP LAMP SWITCH-II

1. Adjust stop lamp switch installation. Refer to BR-13, "Inspection and Adjustment".

2. Check harness continuity between stop lamp switch terminals under the following conditions.

Is the inspection result normal? YES >> INSPECTION END

NO >> Replace stop lamp switch.

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