Question for anyone out there who has experience tracing the speaker wires in a 99 TL w/NAVI

Is there a molex-type plug somewhere between the door and the head-unit? The one passenger-side rear door speaker refuses to speak any longer. No clicks, pops, or hissing. Others work fine ( matter of opinion I guess ).
I have yet to, nor do I want to, rip the door pannel appart to test for signal at the speaker connector. Looking for some ideas as to what may have happened from your experiences. ( connectors vibrating themselves off? Wires getting pinched, single channel in head unit burnt?
Only reason I havent replaced the whole system is the NAVI speach ( which still works through the fronts. The sub also is working fine ); .

OR.. is it common to just loose a channel on these Blows head-units?

Thanks for any help in advance..