Jumper wires are simple, yet extremely valuable, pieces of test equipment. They are
basically test wires which are used to bypass sections of a circuit. Although jumper wires
can be purchased, they are usually fabricated from lengths of standard automotive wire
and whatever type of connector (alligator clip, spade connector or pin connector) that is
required for the particular application being tested. In cramped, hard-to-reach areas, it is
advisable to have insulated boots over the jumper wire terminals in order to prevent
accidental grounding. It is also advisable to include a standard automotive fuse in any
jumper wire. This is commonly referred to as a "fused jumper". By inserting an in-line fuse
holder between a set of test leads, a fused jumper wire can be used for bypassing open
circuits. Use a 5 amp fuse to provide protection against voltage spikes.
Jumper wires are used primarily to locate open electrical circuits, on either the ground (
–)
side of the circuit or on the power (+) side. If an electrical component fails to operate,
connect the jumper wire between the component and a good ground. If the component
operates only with the jumper installed, the ground circuit is open. If the ground circuit is
good, but the component does not operate, the circuit between the power feed and
component may be open. By moving the jumper wire successively back from the
component toward the power source, you can isolate the area of the circuit where the
open is located. When the component stops functioning, or the power is cut off, the open is
in the segment of wire between the jumper and the point previously tested.
You can sometimes connect the jumper wire directly from the battery to the "hot" terminal
of the component, but first make sure the component uses 12 volts in operation. Some
electrical components, such as fuel injectors or sensors, are designed to operate on about
4 to 5 volts, and running 12 volts directly to these components will cause damage.
Test Lights
12 volt test light
Summary of Contents for TrailBlazer
Page 1: ......
Page 26: ...Fig 3 Typical body and undervehicle maintenance locations Refer to chart for descriptions ...
Page 29: ......
Page 30: ......
Page 31: ......
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 ...
Page 677: ......