Removal Procedure

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

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Insert a suitable flat-bladed plastic trim tool between the parameter of the high mount stop lamp opening cover (1) and headlining trim panel (2).
Separate the high mount stop lamp opening cover (1) from the headlining trim panel (2).
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Pull downward to release the retaining tabs.
High Mount Stop Lamp Opening Cover (1) - Remove
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High Mount Stop Lamp Bolt (1) - Remove [2x]
Disconnect the electrical connector.
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Release the retaining tabs and separate the high mount stop lamp (1) from the headlining trim panel (2).
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Slide the high mount stop lamp (1) rearward to disengage.
High Mount Stop Lamp (1) - Remove