I am changing my factory stereo to aftermarket in my 02 GP. It's just the basic GM am ,fm, cd.I got the installation kit and it has the one big plug in it and my question is what is the smaller plug on the back of the factory radio? The install kit didnt come with the small plug and no one at the store can tell me what it is? Do I need it for the aftermarket?

do you have Bose or Onstar?

No Bose, no steering wheel controls.Car has onstar, but never activated.

well onstar is incorperated with the stock radio, if you dont want the onstar option, dont worry about the plug, just worry about the GM harness on the aftermarket deck.

Thanks Boosten

if you have steering wheel controls you need a IR adapter and tap the green wire from the oem harness.

scroll up and read, says no steering controlls.