Is there such an adapter?

[dwcopple]

Black must be for reverse

 

[dwcopple]

Black must be for reverse

Nope, light green reverse, blk is gnd

 

[HotWheelsBurban]

That's what I was thinking, that black wire is ground. This is pretty traditional with GM but not enough to say 100% without checking. Why the adapter uses white for ground? Most premade trailer harness wires for 4 prong connection are the standard colors like mentioned earlier. Maybe white insulation is cheaper than black? Easier to see under a vehicle anyway.