Basic Troubleshooting - Chevrolet Trailblazer Service Manual

Basic Troubleshooting

When diagnosing a specific problem, organized troubleshooting is a must. The complexity
of a modern automotive vehicle demands that you approach any problem in a logical,
organized manner. There are certain troubleshooting techniques, however, which are
standard:
Establish when the problem occurs. Does the problem appear only under certain
conditions? Were there any noises, odors or other unusual symptoms? Isolate the
problem area. To do this, make some simple tests and observations, and then
eliminate the systems that are working properly. Check for obvious problems, such
as broken wires and loose or dirty connections. Always check the obvious before
assuming something complicated is the cause.
Test for problems systematically to determine the cause once the problem area is
isolated. Are all the components functioning properly? Is there power going to
electrical switches and motors. Performing careful, systematic checks will often
turn up most causes on the first inspection, without wasting time checking
components that have little or no relationship to the problem.
Test all repairs after the work is done to make sure that the problem is fixed. Some
causes can be traced to more than one component, so a careful verification of
repair work is important in order to pick up additional malfunctions that may cause
a problem to reappear or a different problem to arise. A blown fuse, for example, is
a simple problem that may require more than another fuse to repair. If you don't
look for a problem that caused a fuse to blow, a shorted wire (for example) may go
undetected.
Experience has shown that most problems tend to be the result of a fairly simple and
obvious cause, such as loose or corroded connectors, bad grounds or damaged wire
insulation which causes a short. This makes careful visual inspection of components
during testing essential to quick and accurate troubleshooting.