GM Service Manual Online
For 1990-2009 cars only

Transmission Replacement With 6.6LEngine

Tools Required

    • J 21366 Converter Holding Strap
    • J 44257 Connector Removal Tool

Removal Procedure

Important: If replacing a failed transmission, the "FastLearn" (adapt) procedure must be performed. This can be done in one step using a scan tool. If this procedure is not done, the transmission control module's (TCM's) adaptive values will still be at the settings that it learned for the old transmission, and will be in slow adaptive mode. Under these conditions, it would take an unacceptably long time for the adaptive values to converge to levels suitable for the new transmission.


    Object Number: 401885  Size: SH
  1. Disconnect both of the negative battery cables. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Remove the transmission fluid level indicator.
  3. Raise the vehicle until the right front wheel and tire can be removed. Refer to Lifting and Jacking the Vehicle in General Information.
  4. Remove the right front wheel and tire.
  5. Remove the right front wheel house inner panel retainers (2).
  6. Disconnect any harness retainers attached to the inner panel.
  7. Remove the inner panel (1).

  8. Object Number: 674619  Size: SH
  9. Remove the positive battery cable nut and cable from the starter.
  10. Remove the solenoid nut and wire from the starter.

  11. Object Number: 660305  Size: SH
  12. Remove the starter motor bolts and reposition the starter.

  13. Object Number: 310119  Size: SH
  14. Remove the engine protection shield bolts and shield.

  15. Object Number: 702519  Size: SH

    Important: Rotate the engine clockwise ONLY, rotating the engine counterclockwise may loosen the crankshaft balancer bolt.

  16. Rotate the engine clockwise, using the crankshaft bolt in order to access the torque converter bolts thru the starter opening. Have an assistant rotate the engine while aligning the bolts.
  17. Remove the torque converter bolts.
  18. Completely raise the vehicle.
  19. Drain the transmission fluid.

  20. Object Number: 686691  Size: SH
  21. Disconnect the shift cable from the selector lever ball stud (5) and remove the cable from the bracket (3).

  22. Object Number: 686689  Size: SH
  23. Remove the shift cable bracket bolts and bracket (2) from the transmission.
  24. Reposition the bracket with the cable attached off to the side.

  25. Object Number: 702521  Size: SH
  26. Remove the fuel line retainer (1) bolts on the left side of the transmission.

  27. Object Number: 702523  Size: SH
  28. Remove the fuel line bracket nut from the converter housing stud.

  29. Object Number: 702774  Size: SH
  30. Disconnect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.
  31. Disconnect the output speed sensor (3) electrical connector. If the vehicle is equipped with 4 wheel drive (4WD), the output speed sensor is located on the transfer case and will be disconnected later.

  32. Object Number: 659284  Size: SH
  33. Disconnect the transmission main electrical connector. J 44257 may be used, but is not required.

  34. Object Number: 694239  Size: SH
  35. Disconnect the park/neutral position (PNP) switch electrical connector.
  36. Remove the exhaust hanger bolts and reposition the hanger.
  37. If the vehicle is a 2 wheel drive (2WD), remove the propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement in Propeller Shaft.

  38. Object Number: 647997  Size: SH
  39. Support the transmission with a transmission jack.
  40. If the vehicle is a 2WD, remove the transmission mount nuts.

  41. Object Number: 652595  Size: SH
  42. If the vehicle is a 2WD, remove the transmission support bracket bolts.
  43. If the vehicle is a 2WD, remove the transmission support bolts and nuts.

  44. Object Number: 702771  Size: SH
  45. Remove the transmission mount bolts (1).
  46. Remove the transmission mount.
  47. If the vehicle is equipped with 4WD, remove the transfer case.
  48. • If equipped with a NVG 261-NP2, refer to Transfer Case Assembly Replacement in Driveline/Axle.
    • If equipped with a NVG 263-NP1, refer to Transfer Case Assembly Replacement in Driveline/Axle.
  49. Reposition any wiring harness branches out of the way.

  50. Object Number: 702527  Size: SH
  51. Secure a safety chain around the transmission. Use care not to overlap any wiring, fuel lines, or other related components.

  52. Object Number: 686709  Size: SH
  53. Disconnect the transmission oil cooler lines (1, 2) from the transmission.
  54. Plug the transmission oil cooler line fittings in the transmission case, if necessary.
  55. If the vehicle is equipped with a power take off (PTO) unit , disconnect and/or remove any necessary components to facilitate transmission removal.

  56. Object Number: 702776  Size: SH
  57. Remove the transmission fill tube nuts from the converter housing studs.

  58. Object Number: 702529  Size: SH
  59. Remove the wire harness/vent tube bracket nut from the converter housing stud and reposition the bracket.

  60. Object Number: 686685  Size: SH
  61. Remove the remaining converter housing bolts and studs.
  62. Separate the transmission from the engine.

  63. Object Number: 702530  Size: SH
  64. Install J 21366 to the converter housing in order to keep the torque converter from sliding off of the turbine shaft.
  65. Carefully lower the transmission from the vehicle while simultaneously removing the fill tube.
  66. Remove the J 21366 .

Installation Procedure


    Object Number: 702530  Size: SH
  1. Install J 21366 to the converter housing in order to keep the torque converter from sliding off of the turbine shaft.
  2. Raise the transmission into place while simultaneously installing the transmission fill tube.
  3. Remove the J 21366
  4. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 686685  Size: SH

    Important: Do not install the transmission by drawing it to the engine using the studs and bolts.

  5. Align the transmission with the engine using the alignment dowels located at the rear of the engine.
  6. Important: Ensure that the torque converter can be rotated before tightening the bolts and studs.

  7. Install the converter housing bolts and studs.
  8. Tighten
    Tighten the bolts/studs to 50 N·m (37 lb ft).


    Object Number: 702529  Size: SH
  9. Install the wire harness/vent tube bracket and nut to the converter housing stud.
  10. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 702776  Size: SH
  11. Install the transmission fill tube and nuts to the converter housing studs.
  12. Tighten
    Tighten the nuts to 18 N·m (13 lb ft).

  13. If the vehicle is equipped with a PTO unit, connect and/or install the components at this time.

  14. Object Number: 702527  Size: SH
  15. Remove the safety chain from around the transmission.
  16. Install the transfer case, if the vehicle is equipped with 4WD.
  17. • If equipped with a NVG 261-NP2, refer to Transfer Case Assembly Replacement in Driveline/Axle.
    • If equipped with a NVG 263-NP1, refer to Transfer Case Assembly Replacement in Driveline/Axle.

    Object Number: 702771  Size: SH
  18. If the vehicle is a 2WD, install the transmission mount.
  19. If the vehicle is a 2WD, install the transmission mount bolts (1).
  20. Tighten
    Tighten the bolts to 50 N·m (37 lb ft).


    Object Number: 652595  Size: SH
  21. Install the transmission support.
  22. If the vehicle is a 2WD, install the transmission support bolts and nuts.
  23. If the vehicle is a 2WD, install the transmission support bracket bolts.
  24. Tighten
    Tighten the bolts/nuts to 95 N·m (70 lb ft).


    Object Number: 647997  Size: SH
  25. If the vehicle is a 2WD, install the transmission mount nuts.
  26. Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

  27. Remove the transmission jack.
  28. If the vehicle is a 2WD, install the propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement in Propeller Shaft.

  29. Object Number: 694239  Size: SH
  30. Position the exhaust hanger and install the bolts.
  31. Tighten
    Tighten the bolts to 12 N·m (106 lb in).

  32. Position the wiring harness branches.
  33. Connect the PNP switch electrical connectors.

  34. Object Number: 702524  Size: SH
  35. Connect the transmission main electrical connector (2).

  36. Object Number: 702774  Size: SH
  37. Connect the output speed sensor (3) electrical connector. If the vehicle is equipped with 4WD, the output speed sensor is located on the transfer case and has been connected during the transfer case installation.
  38. Connect the turbine speed sensor (1) and the input speed sensor (2) electrical connectors.

  39. Object Number: 702523  Size: SH
  40. Install the fuel line bracket and nut to the transmission converter housing stud.
  41. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 702521  Size: SH
  42. Install the fuel line retainer (1) and bolts to the left side of the transmission.
  43. Tighten
    Tighten the bolts to 2.5 N·m (22 lb in).


    Object Number: 686689  Size: SH
  44. Install the shift cable bracket (2) and bolts to the transmission.
  45. Tighten
    Tighten the bolts to 25 N·m (18 lb ft).


    Object Number: 686691  Size: SH
  46. Install the shift cable to the bracket (3) and the selector lever ball stud (5).

  47. Object Number: 713136  Size: SH
  48. Remove the access hole cover (1) on the converter housing in order to rotate the converter and align the first torque converter bolt.

  49. Object Number: 702519  Size: SH
  50. If reusing the torque converter bolts, clean the bolt threads and apply Loctite 242 GM P/N 12345382 (Canadian P/N 10953489), or equivalent to the threads prior to installation.
  51. Install the torque converter bolts.
  52. Tighten
    Tighten the bolts to 60 N·m (44 lb ft).

  53. Install the converter housing access hole cover.

  54. Object Number: 310119  Size: SH
  55. Install the engine protection shield and bolts.
  56. Tighten
    Tighten the bolts to 20 N·m (15 lb ft).


    Object Number: 660305  Size: SH
  57. Position and install the starter motor bolts.
  58. Tighten
    Tighten the bolts to 78 N·m (58 lb ft).


    Object Number: 674619  Size: SH
  59. Install the solenoid wire and nut to the starter.
  60. Tighten
    Tighten the nut to 3.4 N·m (30 lb in).

  61. Install the positive battery cable and nut to the starter.
  62. Tighten
    Tighten the nut to 9 N·m (80 lb in).


    Object Number: 401885  Size: SH
  63. Install the inner panel (1).
  64. Connect any harness retainers to the inner panel.
  65. Install the right front wheel house inner panel retainers (2).
  66. Install the right front wheel and tire.

  67. Object Number: 686709  Size: SH
  68. Remove the plugs from the transmission oil cooler line fittings in the transmission case, if necessary.
  69. Flush the transmission oil cooler and lines, if necessary. Refer to Transmission Fluid Cooler Flushing and Flow Test .
  70. Connect the transmission oil cooler lines (1, 2) to the transmission.
  71. Lower the vehicle.
  72. Connect both negative battery cables. Refer to Battery Negative Cable Disconnection and Connection .
  73. Fill the transmission with new transmission fluid.
  74. Install the transmission fluid level indicator.
  75. If a replacement transmission was installed, perform the "FastLearn" procedure using a scan tool. Refer to FastLearn Procedure .

Transmission Replacement With 8.1L (L18) Engine

Tools Required

    • J 21366 Converter Holding Strap
    • J 44257 Connector Removal Tool

Removal Procedure

Important: If replacing a failed transmission, the "FastLearn" (adapt) procedure must be performed. This can be done in one step using a scan tool. If this procedure is not done, the transmission control module's (TCM's) adaptive valves will be at the settings that it learned for the old transmission, and will be in slow adaptive mode. Under these conditions, it would take an unacceptably long time for the adaptive values to converge to levels suitable for the new transmission.


    Object Number: 310119  Size: SH
  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  2. Remove the transmission fluid level indicator.
  3. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .
  4. Remove the engine protection shield bolts and shield.

  5. Object Number: 747161  Size: SH
  6. Remove the starter motor bolts and position the starter motor aside.
  7. Drain the transmission fluid, if necessary.
  8. If the vehicle is a 2-wheel drive (2WD), remove the propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement .

  9. Object Number: 647997  Size: SH
  10. Support the transmission with a transmission jack.
  11. If the vehicle is a 2WD, remove the transmission mount nuts.

  12. Object Number: 652595  Size: SH
  13. If the vehicle is a 2WD, remove the transmission support bracket bolts.
  14. If the vehicle is a 2WD, remove the transmission support bolts and nuts.
  15. If the vehicle is a 2WD, remove the transmission support.
  16. If the vehicle is equipped with 4-wheel drive (4WD), remove the transfer case.
  17. • If equipped with a NVG 261-NP2, refer to Transfer Case Assembly Replacement .
    • If equipped with a NVG 263-NP1, refer to Transfer Case Assembly Replacement .

    Object Number: 702771  Size: SH
  18. Remove the transmission mount bolts (1).
  19. Remove the transmission mount.

  20. Object Number: 686691  Size: SH
  21. Disconnect the shift cable from the selector lever ball stud (5) and remove the cable from the bracket (3).

  22. Object Number: 686689  Size: SH
  23. Remove the shift cable bracket bolts and bracket (2) from the transmission.

  24. Object Number: 702774  Size: SH
  25. Disconnect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.
  26. Disconnect the output speed sensor (3) electrical connector. If the vehicle is equipped with 4WD, the output speed sensor is located on the transfer case and will already be disconnected.

  27. Object Number: 659284  Size: SH
  28. Disconnect the transmission main electrical connector. J 44257 may be used, but is not required.
  29. Disconnect the park neutral position (PNP) switch electrical connector.

  30. Object Number: 702521  Size: SH
  31. Remove the fuel line retainer (1) bolts on the left side of the transmission.

  32. Object Number: 744180  Size: SH
  33. Remove the transmission heat shield bolt and nut (4, 5) and shield (3).

  34. Object Number: 694239  Size: SH
  35. Remove the exhaust pipe hanger bolts and reposition the hanger.

  36. Object Number: 744180  Size: SH
  37. Remove the transmission heat shield bolts (2) and shield (1).

  38. Object Number: 686693  Size: SH
  39. Remove the converter housing inspection cover bolts and cover.

  40. Object Number: 686680  Size: SH
  41. Rotate the engine clockwise, using the crankshaft bolt in order to access the torque converter bolts through the starter opening. Have an assistant rotate the engine while aligning the bolts.
  42. Remove the torque converter bolts (3).

  43. Object Number: 702776  Size: SH
  44. Remove the transmission fill tube nuts from the converter housing studs.

  45. Object Number: 702523  Size: SH
  46. Remove the fuel line bracket nut from the converter housing stud.

  47. Object Number: 702529  Size: SH
  48. Remove the wire harness/vent tube bracket nut from the converter housing stud and reposition the bracket.

  49. Object Number: 702527  Size: SH
  50. Secure a safety chain around the transmission. Use care not to overlap any wiring, fuel lines, or other related components.

  51. Object Number: 686709  Size: SH
  52. Disconnect the transmission oil cooler lines (1, 2) from the transmission.
  53. Plug the transmission oil cooler line fittings in the transmission case.
  54. If the vehicle is equipped with a power take off (PTO) unit , disconnect and/or remove any necessary components to facilitate transmission removal.

  55. Object Number: 744182  Size: SH
  56. Remove the remaining converter housing bolts and studs.
  57. Separate the transmission from the engine.

  58. Object Number: 702530  Size: SH
  59. Install J 21366 to the converter housing in order to keep the torque converter from sliding off of the turbine shaft.
  60. Carefully lower the transmission from the vehicle while simultaneously removing the fill tube.
  61. Remove the J 21366 .

Installation Procedure


    Object Number: 702530  Size: SH
  1. Install J 21366 to the converter housing in order to keep the torque converter from sliding off of the turbine shaft.
  2. Raise the transmission into place while simultaneously installing the fill tube.
  3. Remove the J 21366 .
  4. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 744182  Size: SH

    Important: Do not install the transmission by drawing it to the engine using the studs and bolts.

  5. Align the transmission with the engine using the alignment dowels located at the rear of the engine.
  6. Install the converter housing bolts and studs.
  7. Tighten
    Tighten the bolts/studs to 50 N·m (37 lb ft).


    Object Number: 702529  Size: SH
  8. Position the wire harness/vent tube bracket and install the wire harness/vent tube bracket nut to the converter housing stud.
  9. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 702523  Size: SH
  10. Install the fuel line bracket nut to the converter housing stud.
  11. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 702776  Size: SH
  12. Install the transmission fill tube nuts to the converter housing studs.
  13. Tighten
    Tighten the nuts to 18 N·m (13 lb ft).


    Object Number: 702527  Size: SH
  14. Remove the safety chain from around the transmission.

  15. Object Number: 686680  Size: SH
  16. Rotate the engine clockwise, using the crankshaft bolt in order to access the torque converter bolts through the starter opening. Have an assistant rotate the engine while aligning the bolts.
  17. If reusing the torque converter bolts, clean the bolt threads and apply Loctite 242 GM P/N 12345382 (Canadian P/N 10953489), or equivalent to the threads prior to installation.
  18. Install the torque converter bolts (3).
  19. Tighten
    Tighten the bolts to 60 N·m (44 lb ft).


    Object Number: 686693  Size: SH
  20. Install the converter housing inspection cover and bolts.
  21. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 744180  Size: SH
  22. Install the transmission heat shield (1) and bolts (2).
  23. Tighten
    Tighten the bolts to 17 N·m (13 lb ft).


    Object Number: 694239  Size: SH
  24. Position the hanger and install the exhaust pipe hanger bolts.
  25. Tighten
    Tighten the bolts to 12 N·m (106 lb in).


    Object Number: 744180  Size: SH
  26. Install the transmission heat shield (3) and bolt/nut (4, 5).
  27. Tighten
    Tighten the bolt/nut to 17 N·m (13 lb ft).


    Object Number: 702521  Size: SH
  28. Install the fuel line retainer (1) bolts to the left side of the transmission.
  29. Tighten
    Tighten the bolts to 2.5 N·m (22 lb in).


    Object Number: 702524  Size: SH
  30. Connect the PNP switch electrical connector.
  31. Disconnect the transmission main electrical connector (2).

  32. Object Number: 702774  Size: SH
  33. Connect the output speed sensor (3) electrical connector. If the vehicle is equipped with 4WD, the output speed sensor is located on the transfer case and will be disconnected later.
  34. Connect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.

  35. Object Number: 686689  Size: SH
  36. Install the shift cable bracket (2) and bolts to the transmission.
  37. Tighten
    Tighten the bolts to 25 N·m (18 lb ft).


    Object Number: 686691  Size: SH
  38. Connect the shift cable to the selector lever ball stud (5) and install the cable to the bracket (3).

  39. Object Number: 702771  Size: SH
  40. Install the transmission mount.
  41. Install the transmission mount bolts (1).
  42. Tighten
    Tighten the bolts to 50 N·m (37 lb ft).

  43. If the vehicle is equipped with 4WD, install the transfer case.
  44. • If equipped with a NVG 261-NP2, refer to Transfer Case Assembly Replacement .
    • If equipped with a NVG 263-NP1, refer to Transfer Case Assembly Replacement .

    Object Number: 652595  Size: SH
  45. If the vehicle is a 2WD, install the transmission support.
  46. If the vehicle is a 2WD, install the transmission support bolts and nuts.
  47. If the vehicle is a 2WD, install the transmission support bracket bolts.
  48. Tighten
    Tighten the bolts/nuts to 95 N·m (70 lb ft).


    Object Number: 647997  Size: SH
  49. If the vehicle is a 2WD, install the transmission mount nuts.
  50. Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

  51. Remove the transmission jack from the transmission.
  52. If the vehicle is a 2WD, remove the propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement .

  53. Object Number: 747161  Size: SH
  54. Position the starter motor and install the starter motor bolts.
  55. Tighten
    Tighten the bolts to 50 N·m (37 lb ft).


    Object Number: 310119  Size: SH
  56. Install the engine protection shield and bolts.
  57. Tighten
    Tighten the bolts to 20 N·m (15 lb ft).

  58. If the vehicle is equipped with a PTO unit, connect and/or install any necessary components.

  59. Object Number: 686709  Size: SH
  60. Remove the plugs from the transmission oil cooler line fittings in the transmission case.
  61. Flush the transmission oil cooler and lines, if necessary. Refer to Transmission Fluid Cooler Flushing and Flow Test .
  62. Connect the transmission oil cooler lines (1, 2) to the transmission.
  63. Lower the vehicle.
  64. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  65. Fill the transmission with new transmission fluid.
  66. Install the transmission fluid level indicator.
  67. If a replacement transmission was installed, perform the "FastLearn" procedure using a scan tool. Refer to FastLearn Procedure .