Dave,

Glad you found what you needed for the diodes. As for your need for info on circuits I have a suggestion that may be of great assistance. You can actually buy a trial subscription to the GM Service Information database. It costs $20 for a 3 day subscription and given the nature of your project I feel that it is well worth it. If you were simply needing a couple wiring diagrams then $20 might be a little steep, but the intensity of your project warrants the cost IMHO. The amount of knowledge that you can obtain can prove quite invaluable because, aside from being able to view and print any and every diagram that you need, you can also view a detailed description and operation of any and all systems of the vehicle. The trial subscription gives you unrestricted access to all sections of SI so you can access any info that is available there. I have used the trial subscription once before when I needed some detailed repair info for a couple of my vehicles after my former employer had finally removed me from the GM system. I'll attach a link to the site where you can purchase the subscription and access everything. https://www.acdelcotds.com/acdelco/action/subscribehome

HTH,
Phil