'92 pathfinder stereo wire harness

Hi all- My ride was broken into and they took my stereo. I bought a new stereo and tried to install it but I have no power. After touching a few wires, I heard a relay clicking in my left engine compartment. All of my fuses are good. The wire harness has three separate leads. The large one plugs into the leads on my stereo harness. The middle sized one has 5 terminals, with four of them supposedly for the factory pre-amp for the rear speakers. I was told it was bypassed so I ran new wires to new rear 6 by 9's. The small plug-in I dont know what its for. Am I missing a fusebox somewhere or is it possibly I blew a relay. I was told to check the A fuse and T fuse but I dont understand that. Can anyone help?

Have you checked the fuses with the ignition switched on? There may be two different fuse boxes in this vehicle, under the dash and under the hood. Do you have a test light? A visual inspection of fuses can be misleading.

Hey Db and all- I guess I was wrong. The stereo now works in the daytime but tonight I was going to go for a ride. I fired up the stereo and everything was fine until I turned my headlights on and then the stereo went off. What the heck did I do now? I was only looking for a ground and I guess I didnt find it.