Nissan Altima 2007-2012 Service Manual: P0841 pressure sensor function

Description

Using the engine load (throttle position), the primary pulley revolution speed, and the secondary pulley revolution speed as input signal, TCM changes the operating pressure of the primary pulley and the secondary pulley and changes the groove width of the pulley to control the gear ratio.

DTC Logic

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

CAUTION: Always drive vehicle at a safe speed. NOTE: If “DTC CONFIRMATION PROCEDURE” has been previously performed, always turn ignition switch OFF.

Then wait at least 10 seconds before performing the next test.

1.CHECK DTC DETECTION

1. Turn ignition switch ON.

2. Select “DATA MONITOR”.

3. Start engine and maintain the following conditions for at least 12 consecutive seconds.

Is “P0841 PRESS SEN/FNCTN” detected? YES >> Go to TM-344, "Diagnosis Procedure".

NO >> Check intermittent incident. Refer to GI-42, "Intermittent Incident".

Diagnosis Procedure

1.CHECK LINE PRESSURE

Perform line pressure test. Refer to TM-423, "Inspection and Judgment".

Is the inspection result normal? YES >> GO TO 2.

NO >> Repair or replace damaged parts. Refer to TM-423, "Inspection and Judgment".

2.CHECK TRANSMISSION FLUID PRESSURE SENSOR A (SECONDARY PRESSURE SENSOR) SYSTEM

Check transmission fluid pressure sensor A (secondary pressure sensor) system. Refer to TM-341, "Description".

Is the inspection result normal? YES >> GO TO 3.

NO >> Repair or replace damaged parts.

3.CHECK PRESSURE CONTROL SOLENOID VALVE A (LINE PRESSURE SOLENOID VALVE)

1. Turn ignition switch OFF.

2. Disconnect CVT unit connector.

3. Check pressure control solenoid valve A (line pressure solenoid valve). Refer to TM-345, "Component Inspection [Pressure Control Solenoid Valve A (Line Pressure Solenoid Valve)]".

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

NO >> Replace transaxle assembly. Refer to TM-447, "Exploded View".

4.CHECK PRESSURE CONTROL SOLENOID VALVE B (SECONDARY PRESSURE SOLENOID VALVE)

Check pressure control solenoid valve B (secondary pressure solenoid valve). Refer to TM-345, "Component Inspection [Pressure Control Solenoid Valve B (Secondary Pressure Solenoid Valve)]".

Is the inspection result normal? YES >> GO TO 5.

NO >> Replace transaxle assembly. Refer to TM-447, "Exploded View".

5.CHECK STEP MOTOR SYSTEM

Check step motor system. Refer to TM-361, "Description".

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

NO >> Repair or replace damaged parts.

6.DETECT MALFUNCTIONING ITEMS

Check TCM connector pin terminals for damage or loose connection with harness connector.

Is the inspection result normal? YES >> Replace TCM. Refer to TM-430, "Exploded View".

NO >> Repair or replace damaged parts.

Component Inspection [Pressure Control Solenoid Valve A (Line Pressure Solenoid Valve)]

1.CHECK PRESSURE CONTROL SOLENOID VALVE A (LINE PRESSURE SOLENOID VALVE)

Check resistance between CVT unit terminal 2 and ground.

Is the inspection result normal? YES >> INSPECTION END

NO >> Replace transaxle assembly. Refer to TM-447, "Exploded View".

Component Inspection [Pressure Control Solenoid Valve B (Secondary Pressure Solenoid Valve)]

1.CHECK PRESSURE CONTROL SOLENOID VALVE B (SECONDARY PRESSURE SOLENOID VALVE)

Check resistance between CVT unit terminal 3 and ground.

Is the inspection result normal? YES >> INSPECTION END

NO >> Replace transaxle assembly. Refer to TM-447, "Exploded View".

    P0840 transmission fluid pressure sensor A (sec pressure sensor)
    Description The transmission fluid pressure sensor A (secondary pressure sensor) detects secondary pressure of CVT and sends TCM the signal. DTC Logic DTC DETECTION LOGIC DTC CONFIRMATION PR ...

    P0868 secondary pressure down
    Description The pressure control solenoid valve B (secondary pressure solenoid valve) regulates the secondary pressure to suit the driving condition in response to a signal sent from the TCM. DTC ...

    Other materials:

    B Terminal circuit
    Description The terminal “1” (B) circuit supplies power to charge the battery and operate the vehicles electrical system. Diagnosis Procedure 1.CHECK TERMINAL “1” CONNECTION 1. Turn ignition switch OFF. 2. Check if terminal “1” is clean and tight. Is the inspection result no ...

    Cowl top
    Removal and Installation 1. Cowl top seal 2. Cowl top side trim covers 3. Cowl top foam blocks 4. Cowl top A Clips REMOVAL 1. Remove both the RH and LH wiper arms. Refer to WW-116, "FRONT WIPER ARMS : Removal and Installation". 2. Remove the cowl top side trim covers. 3. ...

    On-vehicle maintenance
    FUEL SYSTEM Inspection Inspect fuel lines, fuel filler cap and fuel tank for improper attachment, leaks, cracks, damage, loose connections, chafing or deterioration. If necessary, repair or replace damaged parts. Quick Connector CAUTION: • After connecting fuel tube quick connectors, m ...