04 silverado electrical

Ok I got a new harness for the headlights to day and the new harness has a red Hotwire for the fuse box. Any idea wat it powers? Old harness didn't have that. Also came with a small fuse box that mounts beside the big fuse / relay box. Any idea wat that's for? If u have a fuse diagram for the little 1 that would help. Last thing. I also picked up this little sensor thing that goes around the neg batt cable, my 20oo don't have this. It plugs in to a purple plug out of the electrical area. Wats it for?

u bought a '04 harness for a '00 truck. start there!

No, iv had a 2000 z71, I just got an 04 2 wheel drive with a 6.0 swap, I'm trin to get the electrical right on it.

Ok I fig it out, the extra fues box is for factory elec fans, any ideas what the thing around the batt cable is for?

Are you talking about a lose connector inside the fuse block? I think that may be used for 4wd. I recall having that plug which wasn't needed on my 2wd. I also had an thick red wire that wasn't used and I think that was for a trailer brake set up. But, mine is an '02 harness.

No it's off a 2wd, it's was a fuse block for the factory fans I fig it out. I'm tring to see what the thing is that goes around the neg batt cable and plugs in to the harness

Heavy (blue) 10awg wire is for electric brakes.... if you have factory 7 way there would be wire from rear of truck plug all way up to front of engine bay.

Heavy (red) 10awg wire with a small eyelet is for 12vdc Battery charge, that wire also runs to the back of the 7 way plug.

Now depending on how well equipped your truck is with factory opinions it might just be a "plug and play" and you will not need those wires.