Thanks for your reply. I found after thorough digging and checking with my tester that the top brake/tail light uses all three wires on the new socket. The pink center hooks to brown and the blue hooks to blue. Of course the black is ground. But on the original second, blinker socket it uses two blacks and a blue. Those 2 black wires are connected together to continue the ground up to the top brake/tail light socket. The center wire on that one of my new one isn't used. So I dropped and taped up that center wire, took the black on the new sockets for both top brake/tail light and second blinker and connected them together, and using some spare wiring connected those 2 ground wires to the black ground going down the harness, which also hooks to the black side of the reverse light at the bottom.
I hope that explains it and I don't confuse you, lol. It looks like the reverse bottom only uses the outer 2 wires. Ground and hot, and center wire of it is the ground connected inside it's socket, also. So reverse bottom and blinker middle are only 2 wire sockets while the top brake/tail light is a 3 wire socket. The same ground continues to be used and extended for all 3 sockets.
Anyway, thanks for your help and advice. I looked at the part number you gave and it does look like the correct part number. Driver's side is 16531401 and passenger side is 16531402 in case anyone asks. It runs from around 2002 thru 2007 or so for that same harness I believe. If this gives me problems i'll change them both and forget changing socket ends. It's a big hassle that's for sure.
Oh, and the new sockets and old sockets have the same rubber bushing so I put them both on each socket so it seals tightly, although it was a bit hard to push in and twist. The aftermarket taillight lense I got was slightly thinner at the holes so the original sockets and these new ones didn't tighten up enough to be water tight. They are now. And thankfully I now have my 3157 LED's and sockets all brand new and working great.
Friday, February 26th, 2021 AT 9:49 AM