That is exactly what it is for, I have both the flat style and the round style adapters for my Chevy Truck.Racefla said:Maybe a trailer plug if you remove the factory 7 plug.
Yep that may be it. the round 7 pin plug has a socket that looks like this would plug into.
I bet it's for making your flat pigtail hookup.
I think you are correct.GMC FAN said:It is for the trailer brake module. It plugs into the fuse box and the wires attach to the Aftermarket trailer brake module.
Thanks guys--I was wondering too!coloradoGM said:That is exactly what it is for, I have both the flat style and the round style adapters for my Chevy Truck.Racefla said:Maybe a trailer plug if you remove the factory 7 plug.
Yep that may be it. the round 7 pin plug has a socket that looks like this would plug into.
I bet it's for making your flat pigtail hookup.