OK. Some easy stuff.
This diagram shows the connector on the back of the Ignition Barrel. I think. But key is how it identifies the pin numbers in the connector.
The pins are connected in different ways depending on the position of the key. This diagram shows what connects to what:
Now, with this information, you'll want to try and get to the back of the ignition barrel, and do the following tests. If any of these tests don't show the result listed, then there's a problem with the barrel.You'll be wanting to focus on the 'Run Power Circuit' tests, specifically in the 'Run' key position.