Ford Ranger Maintaince And Repair Manual page 651

current were to reach the load in the circuit, the surge could burn it out or severely damage it. It can also
overload the wiring, causing the harness to get hot and melt the insulation. To prevent this, fuses, circuit
breakers and/or fusible links are connected into the supply wires of the electrical system. These items are
nothing more than a built−in weak spot in the system. When an abnormal amount of current flows through the
system, these protective devices work as follows to protect the circuit:
• Fuse−when an excessive electrical current passes through a fuse, the fuse "blows" (the conductor
melts) and opens the circuit, preventing the passage of current.
Most vehicles use one or more fuse panels. This one is located on the driver's side kick panel
• Circuit Breaker−a circuit breaker is basically a self−repairing fuse. It will open the circuit in the same
fashion as a fuse, but when the surge subsides, the circuit breaker can be reset and does not need
replacement.
Fusible Link−a fusible link (fuse link or main link) is a short length of special, high temperature
•
insulated wire that acts as a fuse. When an excessive electrical current passes through a fusible link,
the thin gauge wire inside the link melts, creating an intentional open to protect the circuit. To repair
the circuit, the link must be replaced. Some newer type fusible links are housed in plug−in modules,
which are simply replaced like a fuse, while older type fusible links must be cut and spliced if they
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HOW TO USE THIS BOOK
PROTECTIVE DEVICES