Ford Aerostar 1986-1997 Repair Guide

Fusible Links


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:

  1. Determine which circuit is damaged, its location and the cause of the open fuse link. If the damaged fuse link is one of three fed by a common No. 10 or 12 gauge feed wire, determine the specific affected circuit.
  3. Disconnect the negative battery cable.
  5. Cut the damaged fuse link from the wiring harness and discard it. If the fuse link is one of three circuits fed by a single feed wire, cut it out of the harness at each splice end and discard it.
  7. Identify and procure the proper fuse link and butt connectors for attaching the fuse link in the harness.
  9. To repair any fuse link in a 3-link group with one feed:
    1. After cutting the open link out of the harness, cut each of the remaining undamaged fuse links close to the feed wire weld.
    3. Strip approximately 1 / 2 in. (12.7mm) of insulation from the detached ends of the two good fuse links. Then insert two wire ends into one end of a butt connector, and carefully push one stripped end of the replacement fuse link into the same end of the butt connector. Crimp all three firmly together.


Care must be taken when fitting the three fuse links into the butt connector, as the internal diameter is a snug fit for three 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.

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.