I'm going to make a couple of guesses. One is that the keyless entry was built into the stock radio. That kind of integration is common these days. The other possibility is that the radio sent power to the keyless entry along with the power to the antenna preamp in the rear hatch. Is your AM/FM reception poor? If so, that's a clue. Hopefully someone with a wiring diagram can give us more information.
the fm/am are comming in clear. i thought that it might be a possibility of the keyless entry being on the stock radio. but is there a way around that or is that the consequences of getting a new radio.