Do you get sound from the speakers when they are not attached to the door?
I had one once that worked until I put it in the door. When installed, the terminals on the speaker were barely touching the metal on the door and shorting it out.
Sent from my iPhone using Tapatalk
This is also a possibility. I had a set of speakers in the rear deck of an old Maxima that would occasionally cut out and I had a hell of a time figuring it out. Turns out that the way they were mounted caused part of the trunk latch mechanism to make contact with the terminals, but ONLY when the trunk lid was closed. I had a few major head scratch moments laying back there looking up, trying to figure out what in the hell was going on. Finally moved the trunk lid and watched that bar move closer... "Oh ****..."
I turned them 1/4 turn in the holes and never had that problem again.