Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Infiniti >> 2003 >> I35 >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transaxle >> Diagnostic Trouble Code Definitions >> DTC P0744: A/T TCC S/V Function (Lock-Up) >> Diagnostic Procedure

Diagnostic Procedure

  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?

    Fig 1: Checking Shift Up D3 To D4 Diagnostic Procedure
    G02090696Courtesy of NISSAN MOTOR CO., U.S.A.
    1. Yes or No 

    Yes: GO TO  11.

    No: GO TO 2.

  2. Check Line Pressure 

    Perform line pressure test.

    Refer to LINE PRESSURE TEST .

    Fig 2: Identifying Line Pressure Table
    G02090697Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO 3.

    NG: GO TO  6.

  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 obstacies.
      Fig 3: Checking Control Valve Assembly
      G02090698Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO 4.

    NG: Repair control valve.

  4. Check Shift Up (D 3  To D 4  ) 

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

    1. OK or NG 

    OK: GO TO 5.

    NG: Check control valve again. Repair or replace control valve assembly.

  5. Check DTC 

    Perform DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE .

    1. OK or NG 

    OK: INSPECTION END 

    NG: GO TO  11. Check for proper lock-up.

  6. Check Solenoid Valve Resistance 
    1. Remove control valve assembly. Refer to CONTROL VALVE ASSEMBLY AND ACCUMULATORS .
      • Line pressure solenoid valve
    2. Check resistance to the terminal and ground.
      Fig 4: Checking Solenoid Valve Resistance System
      G02090699Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO  8.

    NG: Replace solenoid valve assembly.

  7. Check Solenoid Valve Operation 
    1. Remove control valve assembly. Refer to CONTROL VALVE ASSEMBLY .
      • Line pressure solenoid valve
    2. Check solenoid valve by listening for its operating sound while applying battery voltage to the terminal and ground.
      Fig 5: Checking Solenoid Valve Operation System
      G02090700Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO 8.

    NG: Replace solenoid valve assembly.

  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
      Fig 6: Checking Control Valve Assembly
      G02090701Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO 9.

    NG: Repair control valve.

  9. Check Shift Up (D 3  To D 4  ) 

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

    1. OK or NG 

    OK: GO TO 10.

    NG: Check control valve again. Repair or replace control valve assembly.

  10. Check DTC 

    Perform DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE .

    1. OK or NG 

    OK: Inspection End 

    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?

    Fig 7: Identifying A/T Perform Lock-Up At Specified Speed System
    G02090702Courtesy of NISSAN MOTOR CO., U.S.A.
    1. Yes or No 

    Yes: Perform "Cruise test - Part 1" again and return to the start point of this test group.

    No: GO TO 12.

  12. Check Solenoid Valve Resistance 
    1. Remove control valve assembly. Refer to CONTROL VALVE ASSEMBLY AND ACCUMULATORS .
      • Torque converter clutch solenoid valve
    2. Check resistance to the terminal and ground.
      Fig 8: Checking Solenoid Valve Terminal Resistance
      G02090703Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO  14.

    NG: Replace solenoid valve assembly.

  13. Check Solenoid 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.
      Fig 9: Checking Solenoid Valve Operation
      G02090704Courtesy of NISSAN MOTOR CO., U.S.A.
    1. OK or NG 

    OK: GO TO 14.

    NG: Replace solenoid valve assembly.

  14. Check Control Valve 
    1. Disassemble control valve assembly. Refer to CONTROL VALVE ASSEMBLY .
    2. Check control valves for sticking.
      Fig 10: Checking Control Valve Assembly
      G02090705Courtesy of NISSAN MOTOR CO., U.S.A.
      • Torque converter clutch control valve
      • Torque converter clutch relief valve
    1. OK or NG 

    OK: GO TO 15.

    NG: Repair control valve.

  15. Check Lock-Up 

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

    1. Yes or No 

    Yes: GO TO 16.

    No: Check control valve again. Repair or replace control valve assembly.

  16. Check DTC 

    Perform DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION PROCEDURE .

    1. OK or NG 

    OK: Inspection End 

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

scientia non olet · About Mike's Workshop Manuals