Transmission Replacement With 6.6L (LB7) Engine

Tools Required

Important: If replacing a failed transmission, it is important to reset the transmission control module (TCM) to base calibration and fast adaptive for all shifts. This can be done in one step with a scan tool. If this is not done, the 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.

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 (2).



8. Remove the positive battery cable nut and cable from the starter.
9. Remove the solenoid nut and wire from the starter.



10. Remove the starter motor bolts and reposition the starter.



11. Remove the engine protection shield bolts and shield.




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

12. 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.
13. Remove the torque converter bolts.
14. Completely raise the vehicle.
15. Drain the transmission fluid.



16. Disconnect the shift cable from the selector lever ball stud (5) and remove the cable from the bracket (3).



17. Remove the shift cable bracket bolts and bracket (2) from the transmission.
18. Reposition the bracket with the cable attached off to the side.



19. Remove the fuel line retainer (1) bolts on the left side of the transmission.



20. Remove the fuel line bracket nut from the converter housing stud.



21. Disconnect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.
22. 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 be disconnected later.



23. Disconnect the transmission main electrical connector. J 44257 may be used, but is not required.



24. Disconnect the park/neutral position (PNP) switch electrical connector.
25. Remove the exhaust hanger bolts and reposition the hanger.
26. Support the transmission with a transmission jack.
27. If the vehicle is a 2WD, remove the propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement in Propeller Shaft.
28. If the vehicle is equipped with 4WD, remove the transfer case.

•	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.

29. Reposition any wiring harness branches out of the way.



30. Secure a safety chain around the transmission. Use care not to overlap any wiring, fuel lines, or other related components.



31. Disconnect the transmission oil cooler lines (1, 2) from the transmission.
32. Plug the transmission oil cooler line fittings in the transmission case.
33. If the vehicle is equipped with a power take off (PTO) unit , disconnect and/or remove any necessary components to facilitate transmission removal.



34. Remove the transmission fill tube nuts from the converter housing studs.



35. Remove the wire harness/vent tube bracket nut from the converter housing stud and reposition the bracket.



36. Remove the remaining converter housing bolts and studs.
37. Separate the transmission from the engine.



38. Install J 21366 to the converter housing in order to keep the torque converter from sliding off of the turbine shaft.
39. Carefully lower the transmission from the vehicle while simultaneously removing the fill tube.
40. Remove the J 21366 .

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 .




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

4. Align the transmission with the engine using the alignment dowels located at the rear of the engine.

Notice: Refer to Fastener Notice in the Preface section.

Important: Ensure that the torque converter can be rotated before tightening the bolts and studs.

5. Install the converter housing bolts and studs.

Tighten
Tighten the bolts/studs to 50 N·m (37 lb ft).




6. Install the wire harness/vent tube bracket and nut to the converter housing stud.

Tighten
Tighten the nut to 18 N·m (13 lb ft).




7. Install the transmission fill tube and nuts to the converter housing studs.

Tighten
Tighten the nuts to 18 N·m (13 lb ft).

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



9. Remove the safety chain from around the transmission.
10. Install the transfer case, if the vehicle is equipped with 4WD.

•	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.

11. 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.
12. Remove the transmission jack.



13. Position the exhaust hanger and install the bolts.

Tighten
Tighten the bolts to 12 N·m (106 lb in).

14. Position the wiring harness branches.
15. Connect the PNP switch electrical connectors.



16. Connect the transmission main electrical connector (2).



17. 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.
18. Connect the turbine speed sensor (1) and the input speed sensor (2) electrical connectors.



19. Install the fuel line bracket and nut to the transmission converter housing stud.

Tighten
Tighten the nut to 18 N·m (13 lb ft).




20. Install the fuel line retainer (1) and bolts to the left side of the transmission.

Tighten
Tighten the bolts to 2.5 N·m (22 lb in).




21. Install the shift cable bracket (2) and bolts to the transmission.

Tighten
Tighten the bolts to 25 N·m (18 lb ft).




22. Install the shift cable to the bracket (3) and the selector lever ball stud (5).



23. Remove the access hole cover (1) on the converter housing in order to rotate the converter and align the first torque converter bolt.



24. 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.
25. Install the torque converter bolts.

Tighten
Tighten the bolts to 60 N·m (44 lb ft).

26. Install the converter housing access hole cover.



27. Install the engine protection shield and bolts.

Tighten
Tighten the bolts to 20 N·m (15 lb ft).




28. Position and install the starter motor bolts.

Tighten
Tighten the bolts to 78 N·m (58 lb ft).




29. Install the solenoid wire and nut to the starter.

Tighten
Tighten the nut to 3.4 N·m (30 lb in).

30. Install the positive battery cable and nut to the starter.

Tighten
Tighten the nut to 9 N·m (80 lb in).




31. Install the inner panel (2).
32. Connect any harness retainers to the inner panel.
33. Install the right front wheel house inner panel retainers (2).
34. Install the right front wheel and tire.



35. Remove the plugs from the transmission oil cooler fittings.
36. Flush the transmission oil cooler and lines, if necessary. Refer to Transmission Fluid Cooler Flushing and Flow Test .
37. Connect the transmission oil cooler lines (1, 2) to the transmission.
38. Lower the vehicle.
39. Connect both negative battery cables . Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
40. Fill the transmission with new transmission fluid.
41. Install the transmission fluid level indicator.

Important: It is recommended that the transmission adaptive pressure (TAP) information be reset.

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the ECM, PCM or TCM will need to relearn the TAP values. Transmission performance may be affected as new TAP values are learned.
42. Reset the TAP values. Refer to FastLearn Procedure .
43. If a replacement transmission was installed, reset the TCM to base calibration and fast adaptive, using a scan tool.

Transmission Replacement With 8.1L (L18) Engine

Tools Required

Important: If replacing a failed transmission with a replacement unit, it is important to reset the transmission control module (TCM) to base calibration and fast adaptive for all shifts.

1. Disconnect the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
2. Remove the fluid level indicator.
3. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
4. Remove the starter motor bolts and position the starter motor aside. Refer to Starter Motor Replacement in Engine Electrical.



5. Drain the transmission fluid, if necessary.
6. Remove the rear propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement in Propeller Shaft.
7. If the vehicle is equipped with 4WD, remove the front propeller shaft. Refer to Front Propeller Shaft Replacement in Propeller Shaft.
8. Support the transmission with a transmission jack.
9. Remove the two nuts securing the transmission mount to the transmission support.



10. Remove the transmission support nuts and bolts.
11. Remove the transmission support from the vehicle.



12. Remove the bolts and remove the transmission mount from the vehicle. Refer to Transmission Mount Replacement .



13. If the vehicle is equipped with 4WD, remove the transfer case. Refer to Transfer Case Assembly Replacement in Transfer Case-NVG 261-NP2 (Two Speed Manual) or Transfer Case Assembly Replacement in Transfer Case-NVG 263-NP1 (Selectable).
14. Remove the shift cable (2) from the selecter lever ball stud (5) and bracket (3). Refer to Range Selector Lever Cable Replacement .



15. Remove the shift cable bracket (2) from the transmission.



16. Remove the bolts from the fuel line retainers (1) on the left side of the transmission.



17. Remove the nut from the stud that retains the fuel line bracket to the converter housing.



18. Disconnect the electrical connectors from the turbine speed sensor (1) and the input speed sensor (2).
19. Disconnect the electrical connector from the output speed sensor (3). If the vehicle is equipped with 4WD, the output speed sensor is located on the transfer case and will already be disconnected.



20. Remove the main electrical connector from the transmission using the J 44257 .



21. Remove the transmission heat shields. Refer to Transmission Heat Shield Replacement .



22. Disconnect the electrical connectors from the park/neutral position switch.
23. Remove the exhaust pipe hanger. Refer to Exhaust Hanger Mounting Bracket Replacement in Engine Exhaust.



24. Secure the transmission safety chain around the transmission. Use care not to overlap any wiring, fuel lines, or other related components that may still be connected to the vehicle.



25. Disconnect the transmission oil cooler lines (1,2) from the transmission. Refer to Transmission Fluid Cooler Hose/Pipe Replacement .
26. Plug the transmission oil cooler line fittings in the transmission case.
27. If the vehicle is equipped with a power take off unit (PTO), disconnect and / or remove the necessary components to facilitate transmission removal.



28. Remove the converter housing inspection cover.



29. Mark the flywheel to torque converter relationship for reassembly purposes.
30. Remove the torque converter bolts (3).



31. Remove the nuts from the studs on the converter housing and position aside the fill tube.



32. Remove the nut from the stud on the converter housing and position aside the wire harness / vent tube retaining bracket.



33. Remove the remaining bolts and studs from the converter housing.
34. Separate the transmission from the engine.



35. Install the J 21366 to the transmission converter housing in order to keep the torque converter from sliding off of the transmission turbine shaft.
36. Carefully lower the transmission from the vehicle while simultaneously removing the fill tube.

1. Install the J 21366 in order to keep the torque converter from sliding off of the transmission turbine shaft.
2. Raise the transmission into place while simultaneously installing the fill tube.
3. Remove the J 21366 .
4. Align the transmission with the engine using the alignment dowels located at the rear of the engine.
5. Ensure that the torque converter can be rotated before tightening the studs and bolts.

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

6. Make sure the transmission is flush against the engine.

Notice: Refer to Fastener Notice in the Preface section.




7. Install the studs and bolts that secure the transmission to the engine.

Tighten
Tighten the studs and bolts to 50 N·m (37 lb ft).




8. Install the wire harness/vent tube retaining bracket to the stud on the converter housing.

Install the nut to the stud that retains the bracket.

Tighten
Tighten the nut to 18 N·m (13 lb ft).




9. Install the fill tube to the studs on the converter housing.

Install the nuts to the studs that retain the fill tube.

Tighten
Tighten the nuts to 18 N·m (13 lb ft).




10. Remove the converter housing access cover (1) to align the first torque converter bolt. Use the marks made during disassembly.



11. 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.
12. Install the torque converter bolts (3).

Tighten
Tighten the bolts to 60 N·m (44 lb ft).




13. Install the converter housing access cover (1).



14. Install the converter housing inspection cover.
15. Install the converter housing inspection cover bolts.

Tighten
Tighten the bolts to 10 N·m (89 lb in).




16. Remove the transmission safety chain from around the transmission.
17. If the vehicle is equipped with a power take off unit (PTO), connect and / or install the components at this time.
18. Install the exhaust pipe hanger. Refer to Exhaust Hanger Mounting Bracket Replacement in Engine Exhaust.



19. Install the transmission heat shield. Refer to Transmission Heat Shield Replacement .



20. Connect the electrical connectors to the park/neutral position switch.
21. Install the main electrical connector (2) to the transmission.



22. Connect the electrical connector to the output speed sensor (3). This sensor is located on the transfer case if the vehicle is equipped with 4WD, and will be connected during transfer case installation.
23. Connect the electrical connectors to the turbine speed sensor (1) and the input speed sensor (2).



24. Install the fuel line bracket to the stud on the transmission converter housing.
25. Install the nut to the converter housing stud that retains the fuel line bracket.

Tighten
Tighten the nut to 18 N·m (13 lb ft).




26. Install the fuel line retainers (1) and bolts to the left side of the transmission.

Tighten
Tighten the bolts to 2.5 N·m (22 lb in).




27. Install the shift cable bracket (2) to the transmission.
28. Install the shift cable bracket bolts to the transmission.

Tighten
Tighten the bolts to 25 N·m (18 lb ft).




29. Install the shift cable (2) to the bracket (3) and the selecter lever ball stud (5). Refer to Range Selector Lever Cable Replacement .



30. Install the transfer case, if equipped. Refer to Transfer Case Assembly Replacement in Transfer Case-NVG 261-NP2 (Two Speed Manual) or Transfer Case Assembly Replacement in Transfer Case-NVG 263-NP1 (Selectable).
31. Install the transmission mount to the transmission. If equipped with 4WD, the transmission mount will be mounted to the transfer case adapter. Refer to Transmission Mount Replacement .
32. Install the transmission mount bolts.

Tighten

•	For 4WD vehicles, tighten the bolts to 47 N·m (35 lb ft).

•	For 2WD vehicles, tighten the bolts to 50 N·m (37 lb ft).




33. Install the transmission support to the vehicle.
34. Install the transmission support nuts and bolts.

Tighten
Tighten the nuts and bolts to 70 N·m (52 lb ft).

35. Lower the transmission.



36. Install the two nuts securing the transmission mount to the transmission support.

Tighten
Tighten the nuts to 40 N·m (30 lb ft).

37. Remove the transmission jack.
38. If equipped with a transfer case, Install the front propeller shaft. Refer to Front Propeller Shaft Replacement in Propeller Shaft.
39. Install the rear propeller shaft. Refer to One-Piece Propeller Shaft Replacement or Two-Piece Propeller Shaft Replacement in Propeller Shaft.
40. Install the starter motor. Refer to Starter Motor Replacement in Engine Electrical.



41. Flush the transmission oil cooler and lines if necessary. Refer to Transmission Fluid Cooler Flushing and Flow Test .
42. Connect the transmission oil cooler lines (1, 2) to the transmission. Refer to Transmission Fluid Cooler Hose/Pipe Replacement .
43. Lower the vehicle.
44. Connect the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
45. Fill the transmission to the proper level with approved fluid.

Important: It is recommended that the transmission adaptive pressure (TAP) information be reset.

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the ECM, PCM or TCM will need to relearn the TAP values. Transmission performance may be affected as new TAP values are learned.
46. Reset the TAP values. Refer to FastLearn Procedure .
47. If a replacement transmission was installed, reset the TCM to base calibration and fast adaptive, using a scan tool.