Find a clean, well-lighted surface free from dust. Put on some music and relax, this may take a little while. You need to put your guitar in a position where you can easily access the main body cavity, where the wiring you will fix is located. Depending on your model of guitar, this will either be located under the pickguard, such as on a Fender Stratocaster, or behind a removable panel on the back of the guitar, such as on Les Paul models and their clones.
Step 2Select a small Phillips screwdriver. You can find appropriate screwdrivers in a jeweler's kit. After you have found the location of the main body cavity--run a search on your specific model if it is not immediately clear--you need to go to work with a small Phillips screwdriver, being careful not to lose or strip any of the screws. If your guitar' s main body cavity is under the pickguard, it is helpful to loosen and remove all the strings. This is often not necessary to remove the pickguard itself, but once you get inside those strings will surely get in the way of what you are doing. After every screw has been removed and set aside, carefully remove the panel covering the main body cavity.
Step 3Take a deep breath, as looking at all those wires running everywhere can be daunting! They will be coated in different colors, and run between the pickups, volume and tone pots, switches, etc., and your guitar's instrument cable input. Guitar wires are often not soldered in place very carefully, especially among cheaper models that are assembled very quickly. They can fray over time, or even break altogether.
Step 4Run your fingers along each of the wires slowly and carefully. If your guitar has simply stopped responding, or doesn't produce any sound when switched between certain pickups, the problem can be in a few different places. The most likely culprit is the wiring headed toward the instrument cable input. These wires can easily become broken or twisted out of place as the guitar is moved and cables are often quickly pushed in and out, or twisted around. The same goes for your volume and tone pots. If the pots themselves have gone bad, more intensive repairs are necessary, which are best left to a professional. But it is likely that the problem will simply be a wire that has broken free at one end from its intended connection.
Step 5Remove any portion of the wire that is hanging onto its contact. Pull it free if it is still partially hanging on, but be very careful as these wires are very delicate. Now use your wire cutters to cut off a small portion of the wire that has become broken or frayed, until there is no metal sticking out from within the wire's plastic casing. Be careful not to snip off so much of the wire that it will no longer reach its target. You are usually given a good length of wire to spare.
Step 6Use a wire stripping tool, or a pocket knife if you do not have a wire stripper, to strip about 3/4 in. of the plastic casing protecting the wire. This is about the time you should plug in your soldering iron, and have lead-free solder at ready while the soldering iron heats up. While stripping the wire, especially if you are using a blade, make sure not to cut the very fine threads. If these become scored or uneven, your problem will likely come back.
Step 7Make sure you have enough of the wire exposed to wrap it carefully around its contact a couple of times. Wrap it tightly so that it holds in place on its own, but make sure there is enough slack that it is tension-free. Your soldering iron should be hot enough by this time.
Step 8Hold the soldering iron physically touching where the wire connects to its contact on your guitar (don't worry, it will not damage these harder metals), and lightly touch a strip of lead-free solder to the tip of the iron. Touch the solder to the iron, not the other way around; it is easier to control this way.
Step 9Wait until the solder heats up enough that it starts to flow, and let the soft, hot metal run around the wire and its contact, until you have a nice little glob that nearly covers the whole area. You have to work quickly here. Set the solder down, and apply the iron directly to the bit of solder now covering the wire. You just want to touch it there for a second, until it runs all over the contact, completely covering the contact and the tip of the wire. If there is not enough to cover, take your stick of solder out and flow a little more into place.
Step 10Set your soldering iron down on a surface where the tip can sit free in the air, and let the hot metal cool down and become hard. Leave it for several minutes before you attempt to move anything around. Now, very carefully plug a cable into the guitar's instrument cable input and into an amplifier. The idea is to test out your repair to see if you have isolated the problem, before you start closing things back up! If you get a tone and your guitar has full functionality again, give yourself a pat on the back! You have fixed the problem and saved a good bit of money in the process! If not, carefully search for any more broken or frayed wires.If there are none, you will likely need to take your guitar into a professional, as further repairs are beyond the scope of the average hobbyist.
Step 11Replace the main body cavity's covering, screw all the screws into place.
*This was first posted by Jesse Sears at eHow.com,the very best in repair information
