engine will not turn over

i replaced the pnp switch (park neutral position). and check all of my fuses they are all ok. i know that voltage is not reaching my solinod on my starter because i check it with a voltmeter. my second step was to replace the ignition switch, but swapping parts out can get to be very expensive. the security light is flashing when the ignition switch is in the on postion. is there a fusible link somewhere that i am looking over. please help

The flashing security lite is the problem here, leave the key on for ten minutes, turn it off for 10 secs. and try to start.

Does your car have the resistor pill in the key (the little black deal with a contact on both sides)? If so, the contacts in the switch could be messed up, not picking up the resistance. There are 2 ways I can think of to fix it...

1. Change the lock cylinder
2. Use your volt meter, measure the resistance of the resistor pill in your key, buy a resistor of the same value, install it between the 2 wires that pick up the resistance of the pill, which will bypass the security system (this is the same method that most remote start systems use to get around it for the GM cars with the resistor pill keys).

If you do a search on google for GM VATS system, you can find a ton of sites that talk about it... one I found even gives the resistor values:
http://www.12vp.com/info_resistors.htm

Hope this helps :)