Bob, I know what you mean.
I had three things going for me.
1. I worked in the automotive electonics field for 12+ years. I think in WIRING. I used to live and breath it 80+ hours a week.
2. I have my motor and tranny out! Easy access to the entire harness and easy to rip apart and put back together
3. I had a complete TT harness with stock resistor pack. How does this help? I was able to rip apart the NA and the TT harness and see where the TT was tapping off wires that were common in the NA harness. They literally have a section of wire stripped back then take a metal band to crimp together 2-4 wires.
Much easier having what the finished product should be to disect sitting in front of you then to guess or look at schematics. This made it a cake walk. I did refer to the shop manual schematic for the inj circuits to ensure what I was seeing in the harnesses was really what was going on.
Simply put both NA and TT ECUs put out the same inj signal. On the NA it just goes directly to the Inj. On the TT that signal just gets put thru the resistor pack first then to the inj.
Where my install got a little fancy is I stole some male/female connectors from teh 91 donor harness to add the new wires needed for the injectors. The NA has a 4 wire setup for the rear set as there are 3 firing wires and one common. The TT has 6 independant wires so I was short two wires. I left the existing 3 independant wires alone, used teh shared as #1 new independant and added the new two wire plug as #2 and #3
Here is the new 6 wire setup and the other side of the plug is wired into the harness in the car. Notice the middle plug has a new 2 wire plug above it.
