In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open circuits can be detected by observation. A blown link often, but not always, has "bubbly" appearing insulation making troubleshooting easier. Always inspect that there is battery voltage past the fusible link to verify continuity.
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes (wire gauges), each fusible link is four wire gauge sizes smaller than the wire it is designed to protect. For example: to protect a 10 gauge wire, use a 14 gauge link (or for metric, to protect a 5mm wire, use a 2mm link). Links are marked on the insulation with wire-gauge size because the heavy insulation makes the link appear to be a heavier gauge than it actually is. The same wire size fusible link must be used when replacing a blown fusible link.
Choose the shortest length that is available. A fusible link should NEVER be longer than nine inches. Fusible links longer than this will not provide sufficient overload protection.
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip the wire and use staking-type pliers to crimp the splice securely in two places. To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each wire harness.