Break Controller Short
 

Saved my old Tekonsha P3 break controller out of my old truck. I ordered the correct wiring harness for my 02 Duramax and tried to hook it up the other day. At first the lights came on the controller and it seemed fine but a few minutes into the drive it started flashing a message that there was a "short to the battery" Just wondering if any of you would know where I need to start to track down the short, or what the problem might be.