K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Maxifuses in future vehicles.
FUSIBLE LINKS
Fig. 3 Good and Damaged Fusible Links
Fig. 6 Wire Size Conversion Table
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, Fig. 3.
Not all fusible link open circuits can be detected by observation. 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, each fusible link
is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 sq.mm wire use a 2 sq.mm link, Fig. 6. Links are marked on the insulation with wire gage size because the heavy insulation makes the
link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(r), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use
fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded
Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(r) fusible links. Hypalon(r) fusible links can only be used to
replace Hypalon(r) fusible links.
Determining characteristics of the types of fusible links:
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Hypalon(r) (limited use): only available in 0.35 sq.mm or smaller and its insulation is one color all the way through.
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SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation.
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Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the
insulation.
Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should
be cut 150-225 mm (approx 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx 9 in.).
