Fusible Link
A short section of specialized thin-gauge wire designed to melt and open an electrical circuit under extreme overload.
A fusible link is a safety device used in high-current automotive electrical circuits. It consists of a short section of specialized wire that is typically four wire gauges smaller than the wire in the circuit it protects. It is insulated with a special fire-resistant material.
The fusible link acts like a slow-blow fuse; if a massive short circuit or electrical overload occurs, the link is designed to heat up, melt, and open the circuit before the primary wiring harness can catch fire. Fusible links are commonly found in the main power feed lines from the battery to the alternator, starter solenoid, and ignition switch.
Unlike standard fuses, which are easily replaced in a fuse block, a blown fusible link must be cut out and a new one spliced into the wiring harness. Symptoms of a blown fusible link include a complete loss of electrical power to the entire vehicle or major circuits, often accompanied by a burning smell or visible melting of the insulated link wire.