First look at the trailer's electrical/lighting connection to the truck, if it is a four-pin connector you are done looking and the trailer likely has surge braking. Surge braking has a tongue in the hitch that puts hydraulic pressure on the trailer's brakes when the trailer hitch puts forward pressure on the ball. Looking at the trailer's hitch, you can easily see surge brake components.
If the trailer has electric braking, your truck will recognize that and the DIC will tell you it detected a trailer connected.
If it has the seven-pin lighting connector, look at the inside back of the wheels, look for a wire. I highly doubt the trailer has electric brakes simply because the majority of vehicles do not have a trailer brake controller. I believe most states do not require trailer brakes until the trailer reaches a GVWR of 3,000 pounds, other states specify 1,500 pounds.
Check this document for your state's requirements;