Chevy Trailblazer no crank testing and information

A big misconception is that the ignition switch is directly tied into the starter. This bad info, combined with a high failure rate of ignition switch failures, leads a lot of people to replace the ignition switch for a no crank. Also, there have been cases where people see the 12v from the ignition switch yellow wire, don't see it at the starter, and assume that there is a break in the non existent wire that connects the ignition switch to the starter.
Here I explain how the starting system works and show you how to test the starter relay inputs and the output.
One thing that I forgot to mention, if every input test passed, and you can jump the relay to make the starter turn on, the problem is most likely the starter relay itself.
UPDATE August 2013 - Hey dumbfucks, if you think it's better to bench test the starter first, by all means be my guest. My way cuts down on diagnostic by ruling out the easy to test shit first.