I had not intended on making an instructable when I started doing this but since I'd documented a few things I figured why not share the info.
I recently bought a 14 year old SUV. A Mitsubishi Montero. Most of the electrical on this old thing had been damaged and or hacked into long before I got to it. Little by little I've gotten almost all the electrical back on line... Recently I decided to put a lighter in the dash. The lines going to the original one needed to be re-ran and I was not about to take the dash apart again, so I snaked a new line through to the fuse block and piggy-backed a line off it; I needed an in-line fuse but it was 2:00AM and no auto-parts store is open then so I made my own. It is very simple, but it works well and it cost me nothing because I already had leftovers from past work.
Step 1: Parts...
The parts you will need... I do not have exact prices because everything I used was leftovers from past works...
an automotive fuse (whatever the correct amp is for your project). a box of em' is only a few dollars.
some wire (heavy enough gauge for whatever you are hooking up). I had 7 feet that cost around 27 cents a foot.
solder and soldering iron. a decent soldering iron is not too expensive... at most around $20
heat-shrink and a lighter. heat-shrink was about five bucks for a big coil of it. ..... lighter, I found it in a parking lot.
zip-ties (if you want to tie the new wire up alongside wires that already are under your dashboard.) a lil' bag is about $7 and lasts a while.
Step 2: Connecting the Tabs of the Fuse to Wire.
Like I said, I had not intended on making an instructable, so I have no image of a fuse before it's soldered to the wire, but here is an image of the pigtails of wire already on the tabs of the fuse.
So I decided to first solder these pigtails on and then afterwords solder these pigtails to the main wire so that I was able to first run the main wire and then simply splice into it in a spot that would be easy to get to if the fuse blows.
Ohhhhh, and by the way, I am not to blame if you jack up or in any way damage your car and/or electrical system. If you do not feel comfortable messing with the electrical system of your car, then don't do this.
Step 3: So Far So Good.
I then got some "heat shrink" and insulated the exposed metal tabs... Heat-shrink is tubes of semi-soft plastic that literally shrinks and forms to the wire you have it around. as seen here ---> http://en.wikipedia.org/wiki/Heat-shrink_tubing <----. Simply hold your lighter under the tubing and carefully move it back and forth untill' it has cinched itself tight on the wire. Now your exposed wire is insulated and won't short out.
Step 4: Where to Put the Fuse?
Then find a spot that you will remember where it is under the dash, and where you will be able to get to it easy enough if the fuse blows. I zip-tied mine to a wire harness that ran alongside the steering column; and made sure that no moving parts like the exposed portion of the column and the arm that goes to the brake peddle might scuff it or pinch it.
Step 5: Sorry, No Photo for This Step.
then splice into the wire you ran and solder the pigtails to the wire. ... I had no photo of this so I made a simple drawing to show an example.
That is pretty much it; Enjoy your electricity.
MarkC214 made it!