I am currently in the process of installing a aftermarket stereo into my jeep. The guy that had it before me had an amp in the back. He needed to run more power to it so I think he hooked it up to the battery. But I don't really know. Right now I just want to install this stereo and to not get myself shocked. Here are some photos that I took. If I could get some instructions that would be awesome! Also I'm not putting in an amp so I just want to get rid of anything that is extra, as you can see I started to pull some wires out already, hopefully I didn't mess things up..

 

Allot is going to depend on how the PO (previous owner) wired it in. If it was done correctly the wire from the battery should have run directly to the amp for the sub (or to a relay) and a trigger wire should have come off the harness (the power antenna trigger is commonly used for this) to switch a relay (or internal relay in the sub amp) and the extra power wire from the battery can (and should if you're not using an amp/sub) be removed. If it was run through a new hole in the firewall (not an existing grommit for an OE wiring penetration) make sure to seal the hole (seam sealer or silicone should do) or water can and will get in (eventually rusting out the floor pans).

It is hard to say what is up with those "trailer taps" on the wiring harness, if you have an aftermarket harness it should list what each wire is for, those taps may be some kind of triggers or may tap into the L/R audio (if the PO's head unit didn't have RCA jacks) to send a signel to the sub. They can probably be disconnected/removed regardless.

 

I found out that the trailer traps where for the diver side speaker. I don't know why he cut them. So I can and should remove that big red wire. What about the big black one right next to it? What should I do with that?

 

Yes, you can remove the big red wire (this is power for the sub/amp) it should be the same wire running into the engine compartment that was connected to the battery. It is probably run under the carpet or along the plastic trim on the sides of the floor. Again if there is a hole in the fire-wall make sure to seal it or it will let water in.

The black wire should be the negitive/ground for the sub/amp, this probably is just screwed into something metal on the body (most steel bodied vehicles including Jeeps use the body as a ground).

The trailer taps were probably used to send a signel to the sub if the OE headunit (or a cheap aftermarket one without RCA output jacks) was used. They really should have used both L and R but this is kind of a half-a**ed way of doing it anyway, so skimping and just tapping into one speaker is not completely unexpected. They really should have gotten a head-unit that had outputs for a sub.