Transmission Replacement

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.





1. Disconnect the negative battery cable.
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. Remove the starter motor bolts and position the starter motor aside.
6. Drain the transmission fluid, if necessary.
7. If the vehicle is a 2 wheel drive (2WD), remove the propeller shaft.





8. Support the transmission with a transmission jack.
9. If the vehicle is a 2WD, remove the transmission mount nuts.





10. If the vehicle is a 2WD, remove the transmission support bracket bolts.
11. If the vehicle is a 2WD, remove the transmission support bolts and nuts.
12. If the vehicle is a 2WD, remove the transmission support.
13. If the vehicle is equipped with 4 wheel drive (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.





14. Remove the transmission mount bolts (1).
15. Remove the transmission mount.





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. Disconnect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.
19. 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.





20. Disconnect the transmission main electrical connector. J 44257 may be used, but is not required.
21. Disconnect the park neutral position (PNP) switch electrical connector.





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





23. Remove the transmission heat shield bolt and nut (4, 5) and shield (3).





24. Remove the exhaust pipe hanger bolts and reposition the hanger.





25. Remove the transmission heat shield bolts (2) and shield (1).





26. Remove the converter housing inspection cover bolts and cover.





27. 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.
28. Remove the torque converter bolts (3).





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





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





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





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





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





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.

Installation Procedure





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

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

Notice: Refer to Fastener Notice in Service Precautions.

5. Install the converter housing bolts and studs.
^ Tighten the bolts/studs to 50 Nm (37 ft. lbs.).





6. Position the wire harness/vent tube bracket and install the wire harness/vent tube bracket nut to the converter housing stud.
^ Tighten the nut to 18 Nm (13 ft. lbs.).





7. Install the fuel line bracket nut to the converter housing stud.
^ Tighten the nut to 18 Nm (13 ft. lbs.).





8. Install the transmission fill tube nuts to the converter housing studs.
^ Tighten the nuts to 18 Nm (13 ft. lbs.).





9. Remove the safety chain from around the transmission.





10. 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.
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 the bolts to 60 Nm (44 ft. lbs.).





13. Install the converter housing inspection cover and bolts.
^ Tighten the bolts to 10 Nm (89 inch lbs.).





14. Install the transmission heat shield (1) and bolts (2).
^ Tighten the bolts to 17 Nm (13 ft. lbs.).





15. Position the hanger and install the exhaust pipe hanger bolts.
^ Tighten the bolts to 12 Nm (106 inch lbs.).





16. Install the transmission heat shield (3) and bolt/nut (4, 5).
^ Tighten the bolt/nut to 17 Nm (13 ft. lbs.).





17. Install the fuel line retainer (1) bolts to the left side of the transmission.
^ Tighten the bolts to 2.5 Nm (22 inch lbs.).





18. Connect the PNP switch electrical connector.
19. Disconnect the transmission main electrical connector (2).





20. 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.
21. Connect the turbine speed sensor (1) and input speed sensor (2) electrical connectors.





22. Install the shift cable bracket (2) and bolts to the transmission.
^ Tighten the bolts to 25 Nm (18 ft. lbs.).





23. Connect the shift cable to the selector lever ball stud (5) and install the cable to the bracket (3).





24. Install the transmission mount.
25. Install the transmission mount bolts (1).
^ Tighten the bolts to 50 Nm (37 ft. lbs.).
26. If the vehicle is equipped with 4WD, install 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.





27. If the vehicle is a 2WD, install the transmission support.
28. If the vehicle is a 2WD, install the transmission support bolts and nuts.
29. If the vehicle is a 2WD, install the transmission support bracket bolts.
^ Tighten the bolts/nuts to 95 Nm (70 ft. lbs.).





30. If the vehicle is a 2WD, install the transmission mount nuts.
^ Tighten the nuts to 40 Nm (30 ft. lbs.).
31. Remove the transmission jack from the transmission.
32. If the vehicle is a 2WD, remove the propeller shaft.





33. Position the starter motor and install the starter motor bolts.
^ Tighten the bolts to 50 Nm (37 ft. lbs.).





34. Install the engine protection shield and bolts.
^ Tighten the bolts to 20 Nm (15 ft. lbs.).
35. If the vehicle is equipped with a PTO unit, connect and/or install any necessary components.





36. Remove the plugs from the transmission oil cooler line fittings in the transmission case.
37. Flush the transmission oil cooler and lines, if necessary.
38. Connect the transmission oil cooler lines (1, 2) to the transmission.
39. Lower the vehicle.
40. Connect the negative battery cable.
41. Fill the transmission with new transmission fluid.
42. Install the transmission fluid level indicator.
43. If a replacement transmission was installed, perform the "FastLearn" procedure using a scan tool. Refer to FastLearn Procedure.