The plenum lower is formed from laminated steel. This steel is constructed by bonding 2 pieces of cold rolled steel (1) with a viscoeleastic layer of adhesive (2). MIG welding laminated steel does not meet GM Corporate standards for structural integrity.

If the lower plenum is damaged beyond repair, a mild steel service replacement panel is available. Once installed, the mild steel replacement panel requires a sound deadening material to duplicate the laminated steel characteristics.

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

1. Disable the supplemental inflatable restraint (SIR) system. Refer to SIR Disabling and Enabling .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
3. Remove all related panels and components.
4. Note the location and remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to Anti-Corrosion Treatment and Repair .
5. Visually inspect the damaged area. Repair as much of the damage as possible to factory specifications. Refer to Dimensions - Body .
6. Remove the upper plenum panel. Refer to Plenum Upper Panel Replacement .




Important: In areas where the lower plenum attaches to the upper dash brackets and strut cap, drill through the lower plenum panel flange only. Do not drill into the attaching panels.

7. Using an 8-mm (5/16-in) spot weld remover, locate and drill out the factory welds om the weld flange connecting the lower plenum to the strut caps (1) and the dash panel (2).



8. Separate the lower plenum from the strut caps using a chisel or equivalent tool.



9. Remove the lower plenum from the vehicle.

1. Drill 8-mm (5/16-in) plug weld holes in the service part in the locations noted from the original panel. In areas above the strut cap where structural adhesive was present, place an additional spot weld between every factory spot weld. Where there are no factory welds, place a plug weld every 40 mm (1 ½ in) (1).
2. Prepare the MIG weld mating surfaces as necessary.
3. Apply GM-approved Weld-Thru Coating or equivalent to all mating surfaces. Refer to Anti-Corrosion Treatment and Repair .



4. Position the service lower plenum panel to the vehicle using 3-dimensional measuring equipment. Clamp the panel into place.



5. Plug weld accordingly.
6. Clean and prepare all welded surfaces.
7. Apply sound deadening material to the bottom side of the service replacement lower plenum. Refer to Sound Deadening Material .
8. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to Anti-Corrosion Treatment and Repair .
9. Paint the repair area. Refer to Basecoat/Clearcoat Paint Systems .

Important: When replacing the original laminated lower plenum with a mild steel service part, the upper plenum can be attached using a typical MIG plug welding process.

10. Install the upper plenum. Refer to MIG Welded Full Panel Replacement .
11. Install all related panels and components.
12. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
13. Enable the SIR system. Refer to SIR Disabling and Enabling