the rear speakers are 4 1/2" and require removing the back deck to get to them. this is not a difficult job
but a time consuming one. you have to remove the back seat first. you can test your amp by using a "good"
speaker and touching a hot wire to your "bad" speaker lead ins, if the "good" speaker works then your amp is ok.
you can do this from the trunk without removing anything. i had both of my back speakers die at once and did
this procedure to find the problem. its wasn't my original idea but a good one.