I don’t know what that plug is for, but I can tell you it’s NOT the electronic brake controller plug/wire..
The electronic brake lead has a large power and ground lead, a large grade wire that goes to the trailer plug and a thinner brake activation lead. Mine is an 08 so I doubt your will be much different, mine was in the area above the brake and accelerator pedals, I removed the large flat panel under the steering wheel and the plug was very easy to find.