Pop Sound at Rear Roof of Cab

A pop sound may heard coming from the rear roof of the cab area on some 2019-2020 Silverado 1500 and Sierra 1500 models and 2020 Silverado 2500HD/3500HD and Sierra 2500HD/3500HD models, built prior to August 3, 2020. The pop sound, which may be heard more often when the cab body is heated or cooled by changing ambient temperatures, may be caused by interference between the Center High Mounted Stop Lamp (CHMSL) and the body of the roof-mounted spoiler. (Fig. 10, #1)


Fig. 10


As these parts expand and contract with changes in ambient conditions, there may be a stick-slip condition that generates the sound. A slight wear mark may be seen in the spoiler paint on some examples. (Fig. 11, #2)


Fig. 11


To create more space between the CHMSL and the spoiler, foam tape should be applied between the CHMSL and the lower corners of the spoiler body (Fig. 12) following the repair procedure in Bulletin #21-NA-018.


Fig. 12


TIP: The eight original central roof spoiler nuts are not reusable. (Fig. 13) The original fasteners should be discarded and replaced.


Fig. 13


For the complete repair procedure as well as parts information, refer to Bulletin #21-NA- 018.


– Thanks to David MacGillis and Kevin Minor

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One Comment


    This spoiler setup is the worst thing that could have happened to these trucks. I’m surprised there isn’t any water leak issues with the solid rear window trucks either, unless there is…

    Would have been easier to just design a more aerodynamic back end of the roof and make the CHMSL lamp have its own little spoiler molded into the lens.

    The biggest problem is its 2021 MY and they STILL can’t stop the water leaks.

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