I have a 1999 Jeep Grand Cherokee "Limited Edition" with everything stock.There is 2 infinity tweeters in the dash and all 4 doors have "Inifinity Gold" speakers...everything was playing when I bought the jeep but, now 1 speaker plays.The others will sometimes come back and play and then stop again.They are off longer than they are on.WHAT THE HELL IS THE PROBLEM.
sounds like somethings come loose, check the connections in the back of the HU, the amp under the back seat and the speakers themselves. try messing with the wires going to the speakers themselves in the doors whith the stereo playing, a friend's car did somehting simular, sound would fade when the car wasn't moving, come back when it was moving. turned out the wire was bad going to the speaker on the passenger side, ran a new one and it fixed the problem.
there should be some screws around the handel and grip on the door. they might be behind panels covering the screw holes. mostly the panel should be held on my clips that just pull out of the door frame. just look around the panel, you should be able to find them.