See Figure 1
A fusible link is a short length of Hypalon (high temperature) insulated wire, integral with the wiring harness, and should not be confused with standard wire. The fusible link is several wire gauges smaller than the circuit it protects, and is designed to melt and break the circuit should an overload occur. Under no circumstances should a fusible link be replaced with a standard length of wire.
The higher melting temperature properties and additional thickness of the Hypalon insulation will usually allow the undersized internal fuse wire to melt and disintegrate within the Hypalon casing with little damage to the high temperature insulation other than discoloration and/or bubbling of the insulation surface. In extreme cases of excessive circuit current, the insulation may separate after the fuse wire has disintegrated, however, the bare wire will seldom be exposed. If it becomes difficult to determine if the fuse link is burnt open, perform a continuity test. When heavy current flows, such as when a booster battery is connected incorrectly or when a short to ground occurs in the wiring harness, the fusible link burns out to protect the alternator and/or wiring.
Production fuse links have a flag moulded on the wire or on the terminal insulator. Color identification of the flag or connector is Blue-20 gauge wire, Red-18 gauge wire, Yellow-17 gauge wire, Orange-16 gauge wire, and Green-14 gauge wire.
To repair any blown fuse link use the following procedure:
- Determine which circuit is damaged, its location and the cause of the open fuse link. If the damaged fuse link is 1 of 3 fed by a common No. 10 or 12 gauge feed wire, determine the specific affected circuit.
- Disconnect the negative battery cable.
- Cut the damaged fuse link from the wiring harness and discard it. If the fuse link is 1 of 3 circuits fed by a single feed wire, cut it out of the harness at each splice end and discard it.
- Identify and procure the proper fuse link and butt connectors for attaching the fuse link in the harness.
To repair any fuse link in a 3-link group with 1 feed:
- After cutting the open link out of the harness, cut each of the remaining undamaged fuse links close to the feed wire weld.
- Strip approximately 1 / 2 in. (12.7mm) of insulation from the detached ends of the 2 good fuse links. Then insert 2 wire ends into 1 end of a butt connector, and carefully push 1 stripped end of the replacement fuse link into the same end of the butt connector. Crimp all 3 firmly together.
Care must be taken when fitting the 3 fuse links into the butt connector, as the internal diameter is a snug fit for 3 wires. Make sure to use a proper crimping tool. Pliers, side cutters, etc. will not apply the proper crimp to retain the wires and withstand a pull test.
- After crimping the butt connector to the 3 fuse links, cut the weld portion from the feed wire and strip approximately 1/2 in. (12.7mm) of insulation from the cut end. Insert the stripped end into the open end of the butt connector and crimp very firmly.
- To attach the remaining end of the replacement fuse link, strip approximately 1/2 in. (12.7mm) of insulation from the wire end of the circuit from which the blown fuse link was removed, and firmly crimp a butt connector to the stripped wire. Then, insert the end of the replacement link into the other end of the butt connector and crimp firmly.
- Using rosin core solder with a consistency of 60 percent tin and 40 percent lead, solder the connectors and the wires at the repairs, and insulate with electrical tape.
- To replace any fuse link on a single circuit in a harness, cut out the damaged portion, strip approximately 1 / 2 in. (12.7mm) of insulation from the 2 wire ends and attach the appropriate replacement fuse link to the stripped wire ends with 2 proper size butt connectors. Solder the connectors and wires, and insulate with tape.
- To repair any fuse link which has an eyelet terminal on 1 end such as the charging circuit, cut off the open fuse link behind the weld, strip approximately 1 / 2 in. (13mm) of insulation from the cut end, and attach the appropriate new eyelet fuse link to the cut stripped wire with an appropriate size butt connector. Solder the connectors and wires at the repair, and insulate with tape.
- Connect the negative battery cable to the battery and test the system for proper operation.
Do not mistake a resistor wire for a fuse link. The resistor wire is generally longer and has print stating, "Resistor: don't cut or splice." When attaching a single No. 16, 17, 18 or 20 gauge fuse link to a heavy gauge wire, always double the stripped wire end of the fuse link before inserting and crimping it into the butt connector for positive wire retention.