Re: 2002 4.3 turns over will not start.
One of my favourite 'tricks' is a voltage drop check. It checks to make sure that there is no bad connections/voltage loss in a circuit. Most understand about measuring voltage, stick the meter black on a good ground and probe with the red and read the voltage... But if you put the meter leads across the same circuit and dial the reading down to the smallest scale, like 200mV, then you'll be looking at any voltage lost in the circuit.
Example. Your coil voltage. We know from the circuit diagram that there should be no 'device' that will use voltage (best way to put it, not completely accurate, but it works) between the battery positive post and the coil + terminal. So, put the red meter lead on the positive post (not the terminal, the post itself) of the battery and the black meter lead on the + terminal of the coil, with the key ON of course. What you should see is a reading of 0, or extremely close to 0. If you have a reading of more than about 50mV, then start looking for a bad connection.
It's a most effective method of finding a bad ground, because you can do it in the negative circuit too. Example. Put the meter black lead on the battery negative post, and the red lead on the body of the starter motor. Now operate the starter motor. See any more than about 10mV, you have a bad connection between the battery and the stater motor. The reason for the lead on the post itself and not the terminal is because corroded terminals are a big culprit. If you suspect a dirty post, just meter between the post and the terminal, it will show up there too.
Good luck,
Chris......