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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 785 (Automatic Transmission) >> DTC P0744: A/T TCC S/V Function (Lock-Up) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK SHIFT UP (D 3  TO D 4  ) 

    During "CRUISE TEST - PART 1 ", does A/T shift from D3 to D4 at the specified speed?

    Yes or No 

    1. Yes: GO TO  11.
    2. No: GO TO 2.
    Fig 1: Checking Shift Up (D3 TO D4 )
    G02160828Courtesy of NISSAN MOTOR CO., U.S.A.
  2. CHECK LINE PRESSURE 

    Perform line pressure test.

    Fig 2: Line Pressure Test Chart DTC P0744
    G02160829Courtesy of NISSAN MOTOR CO., U.S.A.

    Refer to "LINE PRESSURE TEST ".

    OK or NG 

    1. OK: GO TO 3.
    2. NG: GO TO  5.
  3. CHECK CONTROL VALVE 
    1. Disassemble control valve assembly. Refer to "CONTROL VALVE ASSEMBLY ".
    2. Check to ensure that:
    • Valve, sleeve and plug slide along valve bore under their own weight.
    • Valve, sleeve and plug are free from burrs, dents and scratches.
    • Control valve springs are free from damage, deformation and fatigue.
    • Hydraulic line is free from obstacles.

    OK or NG 

    1. OK: GO TO 4.
    2. NG: Repair control valve.
    Fig 3: Identifying Control Valve
    G02160830Courtesy of NISSAN MOTOR CO., U.S.A.
  4. CHECK SHIFT UP (D 3  TO D 4  ) 

    Does A/T shift from D3 to D4 at the specified speed?

    OK or NG 

    1. OK: GO TO 5.
    2. NG: Check control valve again. Repair or replace control valve assembly.
  5. CHECK DTC 

    Perform "DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE ".

    OK or NG 

    1. OK: INSPECTION END 
    2. NG: GO TO  11. Check for proper lock-up.
  6. CHECK VALVE RESISTANCE 
    1. Remove control valve assembly. Refer to "CONTROL VALVE ASSEMBLY AND ACCUMULATORS ".
    2. Line pressure solenoid valve
    3. Check resistance to the terminal and ground.
      Fig 4: Line Pressure Solenoid Valve Resistance Chart DTC P0744
      G02160831Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO  8.
    2. NG: Replace solenoid valve assembly.
    Fig 5: Checking Resistance Between Line Pressure Solenoid Valve Terminal 4 And Ground
    G02160832Courtesy of NISSAN MOTOR CO., U.S.A.
  7. CHECK VALVE OPERATION 
    1. Remove control valve assembly. Refer to "CONTROL VALVE ASSEMBLY AND ACCUMULATORS ".
    2. Line pressure solenoid valve
    3. Check solenoid valve by listening for its operating sound while applying battery voltage to the terminal and ground.

    OK or NG 

    1. OK: GO TO 8.
    2. NG: Replace solenoid valve assembly.
    Fig 6: Checking Operation Of Line Pressure Solenoid Valve
    G02160833Courtesy of NISSAN MOTOR CO., U.S.A.
  8. CHECK CONTROL VALVE 
    1. Disassemble control valve assembly. Refer to "CONTROL VALVE ASSEMBLY ".
    2. Check line pressure circuit valves for sticking.
    • Pressure regulator valve
    • Pilot valve
    • Pressure modifier valve

    OK or NG 

    1. OK: GO TO 9.
    2. NG: Repair control valve.
    Fig 7: Identifying Control Valve
    G02160834Courtesy of NISSAN MOTOR CO., U.S.A.
  9. CHECK SHIFT UP (D 3  TO D 4  ) 

    Does A/T shift from D3 to D4 at the specified speed?

    OK or NG 

    1. OK: GO TO 10.
    2. NG: GO Check control valve again. Repair or replace control valve assembly.
  10. CHECK DTC 

    Perform "DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE ".

    OK or NG 

    1. OK: INSPECTION END 
    2. NG: GO TO 11. Check for proper lock-up.
  11. CHECK LOCK-UP 

    During "CRUISE TEST - PART 1 ", does A/T perform lock-up at the specified speed?

    Yes or No 

    1. Yes: Perform "Cruise test - Part 1" again and return to the start point of this test group.
    2. No: GO TO 12.
    Fig 8: Checking Lock Up
    G02160835Courtesy of NISSAN MOTOR CO., U.S.A.
  12. CHECK VALVE RESISTANCE 
    1. Remove control valve assembly. Refer to "CONTROL VALVE ASSEMBLY AND ACCUMULATORS ".
    2. Torque converter clutch solenoid valve
    3. Check resistance to the terminal and ground.
      Fig 9: Torque Converter Clutch Solenoid Valve Resistance Chart DTC P0744
      G02160836Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO  14.
    2. NG: Replace solenoid valve assembly.
    Fig 10: Checking Resistance Between Torque Converter Clutch Solenoid Valve Terminal 5 And Ground
    G02160837Courtesy of NISSAN MOTOR CO., U.S.A.
  13. CHECK VALVE OPERATION 
    1. Remove control valve assembly. Refer to "CONTROL VALVE ASSEMBLY AND ACCUMULATORS ".
      • Torque converter clutch solenoid valve
    2. Check solenoid valve by listening for its operating sound while applying battery voltage to the terminal and ground.

    OK or NG 

    1. OK: GO TO 14.
    2. NG: Replace solenoid valve assembly.
    Fig 11: Checking Torque Converter Clutch Solenoid Valve Operation
    G02160838Courtesy of NISSAN MOTOR CO., U.S.A.
  14. CHECK CONTROL VALVE 
    1. Disassemble control valve assembly. Refer to "CONTROL VALVE ASSEMBLY ".
    2. Check control valves for sticking.
    • Torque converter clutch control valve
    • Torque converter clutch relief valve
    Fig 12: Identifying Control Valve
    G02160839Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 15.
    2. NG: Repair control valve.
  15. CHECK LOCK-UP 

    Does A/T perform lock-up at the specified speed?

    OK or NG 

    1. Yes: GO TO 16.
    2. No: Check control valve again. Repair or replace control valve assembly.
  16. CHECK DTC 

    Perform "DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE ".

    OK or NG 

    1. OK:INSPECTION END 
    2. NG: Perform "Cruise test - Part 1" again and return to the start point of this test group.
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