The flat end goes into the trailer plug. Other end into X Wires are right about the driver side behind rear tire. Some report hard to find. Should be there even with no tow package, that should plug right in. MC
the reason why i asked was because i figured that i can use this harness to tap into for my taillights. the bumper is done and powercoated but it really didnt turn out the way i wanted. i kinda ran out of time and just said f*ck it.