99 Tahoe Trailer Brake Controller Hook up

[ZR800]

I recently purchased a Curt Navigator 1 tailer brake control. I was told to make it simple, go right to the dealer and purchase the harness to hook it up. Much to my surprise this was a special order part and $132. But I ordered it anyway, and now that I have it, I don't think it is the right part. The part # is GM 12137047 (HARNESS A 4.720). It is about 4 feet long and has a 2 pin plug one end, a 4 pin plug on the other, and another 2 pin plug in the middle? And certainly nothing on it has 4 or 5 wire leads that would hook to my brake controller. I was told the part should look like a pig tail that just plugs in and has 4 or 5 wire leads to hook direct to the controller?

Anyone have any info on this?