Van's wiring system checklist question

[Steve]

Here's one for the electrical wizards out there.
Refer to Van's firewall forward and finish kit wiring instructions.

After all the wiring is complete, Van's has the builder apply power and listen for solenoids clicking and checking for 12v in several places. He then has the builder check the mageto P-lead connections with an ohmmeter checking for infinite resistance or zero resistance depending on key switch position.

So far so good.

The next paragraph states to NOT connect the p-leads to the mags while performing the above check because the readings will be incorrect. Question: What is the incorrect value (zero or infinite ohms)? And why?

Thanks all,
Steve

[Mel]

The "P" lead should read "open-to-ground" with the switch in the "mag on" position and should read a "short-to-ground" in the "mag off" position. The switch shorts the mag to ground to disable it.
The reason to do this check without the mag connected is that you will get different readings depending on whether the points are open or closed in the mag.