My car no sparky... does the security system disable the ignition?

On my 300zx, the security warning flashes whenever a door or the hatch is open. It will not prevent the car from starting.

For spark, troubleshoot the ignition system in some kind of heiarchy:
Coil first - spark from coil wire? (try alternate coil, suspect PTU if known good coil doesn't work?)
Individual plug wires - arcing off on metal?
Weak spark ? - cap, rotor

tested for spark from coil- nothing.

connected 12v to coil and brushed ground side to trigger the coil- got spark.

so, i suppose i need to scope the ECM output to the PTU.

BTW, i picked up an extra PTU from ebay... both units ohm out the same. i'm not sure how to test the PTU though.

the flashing light on the dash doesnt make sense in how it operates in my opinion. As previously commented the light blinks anytime a door, hatch or the hood is open. The factory system can disable the ignition, but you would hear the horn go off and the lights would flash in that case. Your car would not crank. If not already done consider getting the FSM and troubleshooting this issue. Its possible the PT is the problem, but also check the fuse in the fusebox by the driver foot. There is a ignition fuse in there.

yeah, but the ignition fuse would be for positive volts.
i get 12v to the coil.

this car is so crappy i don't even know if the security system is still capable of flashing the lights and honking the horn.
the ignition switch is a little messed up too, no return spring so you have to turn back a click after engaging the starter. otherwise it just cranks and cranks by itself.
i know these issues should be fixed, but it shouldn't prevent me from getting spark (unless the ss is disabling the ignition)

Remove the dist cap, turn the ignition key, look and see if the rotor spins. No spin, broken timing belt, big problems. Look at the basics and work from there.

thanks, already checked that.
dist is turning, and the right direction

Turn on the ignition and hotwire the starter motor. This may eliminate the uncommon occasional fault of the ignition turning off when cranking due to a bad ignition switch. Seen it in one Z31 and a few 240Z's.

Also, connect a noid light to one of the easy to get to injector connectors and test for pulse while cranking.