More then likely this is the multi function switch but I included the wiring diagram to confirm this. We just need to turn them on and then test voltage on each coming out of the switch. However, I am pretty sure this is the issue because the brake lights doesn't pass through the switch. That has a separate circuit.
Here is a guide that will help with this testing:
https://www.2carpros.com/articles/how-to-check-wiring
Also, I included the process on how to replace the switch if this proves out.
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Saturday, January 9th, 2021 AT 7:53 AM