Electrical

Automotive Check Engine Light Codes Resource - Diagnostic procedures for the check engine and service engine soon light with trouble code descriptions and test procedures.

Automotive Online Electrical Tutorial - Covers basic electrical issues, alternators, relays and circuitry.

HowStuffWorks: How Turn Signals Work - Photographs and animations describe the unusual device called a thermal flasher that makes your signals flash, and shows how turn signals cancel themselves after you've made your turn.

OBD-II - On-Board Diagnostic System - Dedicated to helping the home and independent technician understand and use OBD-II technology through text, photos, and a discussion forum.

OBD-II Trouble Codes Help Site - Technical procedures on fixing specific Check Engine / OBD-II code problems. Relevant for all 1996-newer vehicles.