i just put the f700bt in my 02 envoy which has onstar i turn the volume up and there is little sound and when it does come in it turns off and on like there is a wire touching and i have checked all the wires what could this be do i need another wiring harness? help!!!

Do you have an interface to communicate with your factory system ? Most newer GM vehicles require that you have one. Some models are different for bose vs non-bose and onstar vs. no-onstar. Newer models will work for either. check out www.pac-audio.com