Call me crude but i keep an extra plug wire with an extra plug hanging on the wall in my shop , i just go one by one on the pack with the plug end laying on the rad core support , this allows me to see if i have spark and its strength by color and general comparison
Yes, let's call the extra plug and wire a test lead. Connect the test lead one by one on one side of the pack, then the other side. If you find one not firing, test the same coil on the other side of the pack.
If both sides aren't firing, that coil is "probably" bad (still could be connector corrosion, wire to or ECM fault), but if one side of the coil gets spark to ground using the test lead, and the other doesn't, the side GETTING spark is probably got a bad wire or spark plug installed and your test lead is replacing that to complete the circuit - somewhat counter intuitive.
The test lead doesn't have to be a spare plug wire and plug. Any piece of wire would work, but using standard, low-voltage/non-ignition wire, you're going to want a way to hold it so your hand is insulated away from the wire core by more than by just the thickness of insulation, and if it were me, I wouldn't have my other hand/arm/etc resting on the (grounded) engine bay.
However I'm not sure I would focus on coil pack too much, IMO when one goes out there would usually be enough misfires to set a misfire code.
