I hope the wiring diagram (051) is some help. I don't know which type of indoor system you are working with. The diagram of the all-fuel control board (053) and the general trouble shooting chart (052) should give you some idea why I referred to this as a complex system.
The service manual is 78 pages, so I can't really post the whole thing!
By the way, if you need a complete wiring diagram for connecting to a specific Goodman indoor unit, they are all in the service manual. There were just too many pages to post, but if you have something specific, I could dig it out. I also looked through the Goodman service bulletin index, and did not see anything pertinent.
I would suspect the compressor for this puppy is north of $650, so that is another reason to be very careful about "poking around" in a system like this.
Most Goodman stuff has a least a 5 year warranty, and your upgraded system may be as much as 10 years. If you might still be in warranty, why would you even mess around???