Why would a beeping warning box appear for trailer brake system with no codes?

Hello, you'll really want to see your local Chevrolet dealership for this, unless you already have so many miles that you're outside of factory warranty. Being that the trailer brake system is a factory related item, you will need to have someone capable off working with diagnostics related to factory equipment to figure out what is going on. www.repairpal.com/repair-shops Try that link for shops near you that may help -- if the dealership is not a viable option for you.