passenger speakers not working

I have an '04 Subaru Legacy. it has the factory radio in it. All right side speakers are not working at all. All the original wiring is in place. Is there a way to test the head unit or the wiring to the speaker without cutting any wires? i tries testing the connections in the wire harness, but it wouldn't work. I am clueless, so any help would be appreciated.

If you know how the harness is pinned out and have a multimeter, you can check the speakers/wiring pretty easily

i did try that, but the leads would not reach into the harness.

Assuming it has no seperate factory amp, then the problem is that one or more speakers are bad or the right side amp in the cd player is bad. The easiest way to test this is by replacement, put a known good cd player or speaker into the place of what's not working.