Not a mopar - 2002 Trailblazer question

Us old-car guys have no problem finding a bad coil-pack. Our clamp-on timing lamps and still useful, just clamp to each spark wire and flash it at your belly. If it doesn't flash - bad coil. I found that 1 of the 3 coils in my 2002 Chrysler 3.8L was bad since the plug wires off it (#2 & #5) didn't make it flash (wasted-spark system). I also heard a faint clicking inside the coil-pack. I 2nd, "don't remove a battery cable when running in 1990+ cars".