This is a classic StewMac video from 1989, transferred to DVD. The quality of this recording is a little dated, but the information is not!
What you need to know to get better sound is all still here.
Explore the basics of guitar wiring with famed repairman Dan Erlewine. Discover helpful tools and see proper soldering techniques;
learn how your guitar's electronic components work, and watch how to install shielding for noise-free sound. Dan also shows you how to unlock your pickups with series, parallel and coil-tap wirings for an expanded sound palate, and how to install active wiring and a preamp. You'll get lots of great tips along the way. 1-hour.