lets check the fuel tank sending unit resistance, 2002 Trailblazer

This is quick to the point demonstration of checking the resistance of a fuel level sensor on a 2002bTrailblazer. We are checking at what I feel is the quickest easiest place for this quick check, and that is the C101 connector adjacent to the underhood fuseblock.
One thing not in the video is that you must NOT jab anything large into the wiring terminal. Not here, not ever anywhere else either. Doing so can spread open the connection and then you have a bad connection that you might not have had before. In fact there is antest called a "pin drag" test where you use a new mating terminal pin and test for tightness in all suspect wiring terminal connectors. They need to be snug.