can you identify this wire for me

[Jeremy_5]

I will try to describe this the best I can, I know a picture would help and if I can get ahold of a digital camera I will go snap one. Anyways, on the heater control there is a yellow half round looking thing, there is two yellow wires running into it. What is this? I am trying to hook up my A.M. radio and the someone did a hack job on the wires, it looks like the wire that runs out of the fuse box labeled "radio" runs to that yellow thing and then is spliced and I think it ran to the old radio. Any help would be appreciated.