Protective Devices
It is possible for large surges of current to pass through the electrical system of the
vehicle. If this surge of 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.
Fuse panel inside 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 melt. Since this link is very early in the electrical path, it's the first
place to look if nothing on the vehicle works, yet the battery seems to be charged
and is properly connected.
Summary of Contents for TrailBlazer
Page 1: ......
Page 26: ...Fig 3 Typical body and undervehicle maintenance locations Refer to chart for descriptions ...
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Page 175: ...Spring free length check Valve spring squareness check ...
Page 192: ...Front of piston mark ...
Page 361: ...5 3L Engine Except Saab Underhood Fuse Block 2003 2005 Early Production ...
Page 469: ...Removing the outer band from the CV boot Removing the inner band from the CV boot ...
Page 470: ...Removing the CV boot from the joint housing Clean the CV joint housing prior to removing boot ...
Page 471: ...Removing the CV joint housing assembly Removing the CV joint ...
Page 472: ...Inspecting the CV joint housing Removing the CV joint outer snap ring ...
Page 473: ...Checking the CV joint snap ring for wear CV joint snap ring typical ...
Page 474: ...Removing the CV joint assembly Removing the CV joint inner snap ring ...
Page 475: ...Installing the CV joint assembly typical ...
Page 553: ...9 Torque the lug nuts to specification 10 Lower the vehicle ...
Page 556: ...Toe in Frame Misalignment Frame misalignment ...
Page 588: ...Bleeding caliper ...
Page 624: ...Manifold gauge set components Refrigerant recovery recycling station ...
Page 676: ...A C Specifications ...
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