Ok, so I installed a factory XM tuner and ran a wiring harness on my (obviously) non pre wired 03 G35C. The end of the harness that goes to the radio has three connectors. As I have no documentation, I am not sure if all 3 are used. One fits in the back of the radio no prob, but are the others used and I'm just not seeing where they go? If I plug in the one, the tuner is not detected. Anyone have experience installing the harness can help me out?

Thanks.