I am in the process of replacing the OEM HU and stumbled across a yellow wire with its own clip attached/taped to the main the radio wiring harness. Does anyone know about this wire's function or purpose?

 

it is the antenna amplifier power lead. hook it up to your power antenna wire or your turn on wire. remember that its only supposed to turn on with the radio!! so hooking it up to a constant power wire would be a no no. if its not hooked up the radio reception is worthless. last time i looked i thought it was yellow with a green tracer, i could be wrong though. good luck!!!!!