2004 Yukon XL Denali trailer wiring

Can anyone tell me for certain whether my Denali is wired for trailer brakes from the factory? I had a dealership mechanic tell me it was but there is no mention in my owner manual. I am under the impression that I need to install a brake controller.
Thanks in advance.
Bill

Can anyone tell me for certain whether my Denali is wired for trailer brakes from the factory?

Mrs. Cusser bought a 2005 Yukon Denali in 2010 to use for towing her horse/trailer. This had an aftermarket brake controller mounted under the dash already. Then the knob/wheel gets adjusted based upon weight/power of the trailer brakes.

I installed one of these into our 1994 Suburban. It installs to battery with a circuit breaker and has a wire to go back to the electrical harness for the trailer plug.

My daughter just bought a 2015 Chevy truck, and was told that was the first year for the electric brake controller to be integrally wired, don't know.

I guess the question is: does the 2004 Denali already have a brake wire going back to the harness, or does that need to be routed? I don't know. But ETrailer has been a good resource in the past. See https://www.etrailer.com/faq-brakecontroller.aspx