93 Pontiac GP....

I have a problem with the ignition on my sons car. When the key is cranked to the "Start" posistion we dont get 12V to the "S" terminal on the starter,,and obviously no crank.

We have verified that the yellow wire ohms from the ignition to the starter while in park and neutral ,,so I know the wireing is good from ignition to starter. I found a constant 12V at the  RED WIRE with a WHITE STRIPE? There is also a Red wire of larger gauge going into the ignition. Am I safe in assuming the RED / Whitestripe wire is the one that is supposed to supply the constant 12v to the ignition? Also where is a place that you can download wireing diagrams for any vehicle? Is there such a place? If I had complete diagrams for this car I could figure it out on my own!!! But the Haynes manual doesnt show any inputs to the ignition.. just the yellow to the Safety switch,,and the purple to the starter "S" terminal.

Thanks in advance for the help!

The red one should also have power if it goes to the ignition switch. Check for fusable links blown or possibly fuses.