This article is from the Car Audio FAQ, by Ian D. Bjorhovde (email@example.com) with numerous contributions by others.
The answer to this section was generously provided by David Navone of
Autosound 2000. The material in these instructions was adapted from
the Autosound 2000 Troubleshooting Flow Chart by Ian Bjorhovde with the
permission of Autosound 2000. For more information about Autosound
2000, (see Section 7).
This is a set of instructions to debug a stereo installation if there
is any noise present after it is completed. Follow each step
carefully! If you have more than one amplifier, repeat level one for
each amp to be sure that none of them are responsible for the noise.