GM Full-Size Trucks 1970-1979 Repair Guide

Fusible Links


See Figure 1

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Fig. Fig. 1: Fusible link repair

In addition to circuit breakers and fuses, the wiring harness incorporates fusible links to protect the wiring. Links are used rather than a fuse, in wiring circuits that are not normally fused, such as the ignition circuit. Fusible links are color coded red in the charging and load circuits to match the color of the circuits they protect. Each link is four gauges smaller than the cable it protects, and is marked on the insulation with the gauge size because the insulation makes it appear heavier than it really is.

The engine compartment wiring harness has several fusible links. The same size wire with a special hypalon insulation must be used when replacing a fusible link.

The links are located in the following areas:

  1. A molded splice at the starter solenoid Bat terminal, a 14 gauge red wire.
  3. A 16 gauge red fusible link at the junction block to protect the unfused wiring of 12 gauge or larger wire. This link stops at the bulkhead connector.
  5. The alternator warning light and field circuitry is protected by a 20 gauge red wire fusible link used in the battery feed to voltage regular #3 terminal. The link is installed as a molded splice in the circuit at the junction block.
  7. The ammeter circuit is protected by two 20 gauge fusible links installed as molded splices in the circuit at the junction block and battery to starter circuit.


  1. Determine the circuit that is damaged.
  3. Disconnect the negative battery terminal.
  5. Cut the damaged fuse link from the harness and discard it.
  7. Identify and procure the proper fuse link and butt connectors.
  9. Strip the wire about 1 / 2 in. on each end.
  11. Connect the fusible link and crimp the butt connectors making sure that the wires are secure.
  13. Solder each connection with resin core solder, and wrap the connections with plastic electrical tape.
  15. Reinstall the wire in the harness.
  17. Connect the negative battery terminal and test the system for proper operation.