Taillights not working

Welcome to 2CarPros.

First, have you checked to make sure there isn't a socket issue? Do the signals work?

I looked through the schematic and it can't be a ground issue if the brake lights work because they have a common ground.

Take a look at the pic I attached. There is a specific fuse and relay for the rear parking lamps. Check fuse, relay, and lets hope it isn't the BCM.

I doubt if you need them, but here are a few links that people find helpful. I personally would start with the fuse. If it's good, confirm there is no power at the light sockets. If they are good, check the relay. Please keep in mind, the headlamp switch itself can be bad.

https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

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Let me know if any of this helps.

Joe