Electric Brake Adjustment

[Willl]

red should go to the blue brake controller and the black to ground?

Wouldn't hurt to keep them all the same just for looks. But like SnowRidge said it probably doesn't matter, neither wire goes to ground in the hub. A quick check with your meter will confirm this.

In addition to connecting all the blacks to frame ground, make sure it's also physically connected to your trailer plug ground.