i had all my rear brake lights (including the central one) go out and thought I'd quickly write up the solution in case it helps anyone.

I checked and replaced (just in case) the main 40 amp fuse under the hood (diagram on cover of fusebox) so assumed it was my brake light switch and replaced that. (remove the knee crash pad, 5 screws, pretty easy to get to). Nothing. I then did some serious wire chasing especially around my trailer hookup.

The solution turned out to be that there are two fuses. The second smaller 15 amp fuse is bottom right in the fuse box on the drivers side of the dash (open the driver side door to see it). That was the issue.

So check both fuses before you get too deep like I did...

Aside from the brake light switch the only other issue I was considering was the multi function indicator switch on the steering column as the brake circuit routes through there. If you have the center brake light still working but not the side brake lights, that could be the issue if you're reading this while trouble shooting and it's not the two fuses.