My thoughts about the connection between the computer code and ECU testing have to do with correlating measured outputs without knowing how the ecu program is treating the inputs and which inputs are important to the fault at hand.

Example from my 850: I find that the ecu is not grounding one contact to the A/C relay. I still do not know enough to fix the problem. Is it a problem with the ecu, or is it a problem with one of the several input lines to the ecu? If I knew what conditions the "computer code" was looking for (I don't even know which inputs are being looked at.) I could measure the signals at the many inputs to see what is wrong.

It is not like troubleshooting a radio or guitar amplifier, where each signal path is visible. (Even here, it is helpful to have a schematic with reference voltages to find problems quickly.) In any computer controlled device, you need to know what the code is doing to perform effective troubleshooting.

Don't take my comments to be discouraging, just a warning that you may find a new "impass" to navigate around.

Dan