GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Lumina Ute 🢒 Body Repair 🢒 Collision Repair 🢒 Rear Underbody Replacement

Removal Procedure

    Caution: Refer to Approved Equipment for Collision Repair Caution in the Preface section.

    Caution: Refer to Vehicle Lifting Caution in the Preface section.

    Caution: Refer to Safety Glasses Caution in the Preface section.

    Caution: Refer to Foam Sound Deadeners Caution in the Preface section.

    Caution: Refer to Battery Disconnect Caution in the Preface section.

  1. Disable the SIR system. Refer to SIR Disabling and Enabling .
  2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  4. Remove the cargo liner. Refer to Cargo Box Liner Replacement .
  5. Remove the rear wheelhouse liner. Refer to Rear Wheelhouse Panel Liner Replacement .
  6. Remove the exhaust system. Refer to Exhaust System Replacement .
  7. Remove the fuel tank. Refer to Fuel Tank Replacement .
  8. Remove the rear bumper fascia. Refer to Rear Bumper Fascia Replacement .
  9. Remove the endgate. Refer to Endgate Replacement .
  10. Note the location and remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to Anti-Corrosion Treatment and Repair .

    11. Object Number: 2021892 Size: SH
  11. Locate, mark and drill out the factory welds attaching the underbody assembly to the seat back panel (1).

    12. Object Number: 2037781 Size: SH
  12. Locate, mark and drill out the factory welds attaching the underbody assembly to the body side assembly (1).

    13. Object Number: 2018549 Size: SH
  13. Note the location of the structural adhesive (1).

    14. Object Number: 2021887 Size: SH
  14. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear frame assembly (1).

    15. Object Number: 2021922 Size: SH
  15. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear frame assembly (1).

    16. Object Number: 2021881 Size: SH
  16. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear frame assembly (1).

    17. Object Number: 2021894 Size: SH
  17. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear frame assembly (1).

    18. Object Number: 2021877 Size: SH
  18. Locate, mark and drill out the factory welds attaching the underbody assembly to the tail lamp panel and the underbody assembly to the lower extension panel of the body side (1).

    19. Object Number: 2018553 Size: SH
  19. Locate, mark and drill out the factory welds attaching the underbody assembly to the body side assembly (1).

    20. Object Number: 2021889 Size: SH
  20. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear frame assembly (1).

    21. Object Number: 2021921 Size: SH
  21. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear crossmember and the underbody assembly to the rear floor panel (1).

    22. Object Number: 2024468 Size: SH

    Important: Clean all adhesive mating surfaces in accordance with the adhesive manufactures specifications.

  22. Locate, mark and drill out the factory welds attaching the underbody assembly to the rear crossmember (1).

Installation Procedure

    Important: Spot welding is the preferred method for attaching panels and should be used whenever possible. A plug weld should only be performed where spot welding is not possible.

    Important: If the location of the original plug weld holes can not be determined, or if structural weld-thru adhesive is present, space the plug weld holes every 32 mm (1¼ in).

    Important: Follow the adhesive manufacturer's instructions during the assembly process. Heat must be applied as per the manufacturer's specifications to cure the adhesives and to expand the sealing baffles.

  1. Drill 8 mm (5/16 in) plug weld holes as necessary in the locations noted when disassembling.

    2. Important: Secondary sealer must be applied to the perimeter of all flanges. Secondary sealer must be applied to all welds/joints that were originally covered by secondary sealer.

  2. Clean and prepare the mating surfaces of both parts of the underbody assembly.

    3. Object Number: 2018549 Size: SH
  3. Apply an approved structural adhesive to the underbody assembly (1).

    4. Object Number: 2021886 Size: SH
  4. Weld the underbody assembly to the rear frame assembly (1) .

    5. Object Number: 2021883 Size: SH
  5. Weld the underbody assembly to the body side (1).

    6. Object Number: 2021895 Size: SH
  6. Weld the underbody assembly to the body side (1).

    7. Object Number: 2037781 Size: SH
  7. Weld the underbody assembly to the body side assembly (1) .

    8. Object Number: 2021885 Size: SH
  8. Weld the underbody assembly to the rear frame assembly (1).

    9. Object Number: 2021888 Size: SH
  9. Weld the underbody assembly to the rear frame assembly (1).

    10. Object Number: 2021893 Size: SH
  10. Weld the underbody assembly to the seat back panel (1) .

    11. Object Number: 2021882 Size: SH
  11. Weld the underbody assembly to the rear frame assembly (1).

    12. Object Number: 2021878 Size: SH
  12. Weld the underbody assembly to the tail lamp panel and the underbody assembly to the lower extension panel of the body side (1).

    13. Object Number: 2021879 Size: SH
  13. Weld the underbody assembly to the rear crossmember and the underbody assembly to the rear floor panel (1).

    14. Object Number: 2021891 Size: SH
  14. Weld the underbody assembly to the rear frame assembly (1).

    15. Object Number: 2021880 Size: SH
  15. Weld the underbody assembly to the rear crossmember (1).
  16. Install the fuel tank. Refer to Fuel Tank Replacement .
  17. Install the Filler Tube. Refer to Filler Tube Replacement .
  18. Install the endgate. Refer to Endgate Replacement .
  19. Install the cargo liner. Refer to Cargo Box Liner Replacement .
  20. Install the exhaust system. Refer to Exhaust System Replacement .
  21. Install the rear wheelhouse liner. Refer to Rear Wheelhouse Panel Liner Replacement .
  22. Install the rear bumper fascia. Refer to Rear Bumper Fascia Replacement .
  23. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  24. Enable the SIR system. Refer to SIR Disabling and Enabling .
  25. If re-programming is required. Refer to Control Module References .