hello, i have read numerous times that a factory gps install is plug and play baisicaly... i have an 01 ml 320 with nav installed, i am suspecting the gps antenna to be faulty, however, the previous owner obviously had the telephone installed, and had it removed when he sold it. the gps signal amplifier seems not to be connected. Does it serve a purpose (for gps tracking)? can i just plug the gps antenna straight to the radio (or other component that i might not be aware of?) which color wire is the gps signal to the radio?? any help would be appreciated. i purchased a secondary gps antenns(with a blue connector) which would plug in the gps amplifier, but still do not get a signal. How dos the signal goto the radio, if the amp only recieves signals???