I agree...if you want to go that route , you can get an actual Laptop interface kit for $59 that will do anything a scanner can and get you Engine mangement values and spec. info.
The led/flash is just a quicky owner retrieve and to make it any more electronically sophisticated is probably not worth the trouble b/c of it's limitations to begin with. The simple $5 led/sw is fine for a DIYer.
One of the main concepts of the tool from the get-go was to get to codes and such without having to get into scanners and HHT tools. It is specifically a Poor Mans scanner by design, with the emphasis on simplicity, low cost, and local/R-Shack components . [ DIYer friendly]
But, I do like that you are searching for a second generation upgrade and applaude your efforts.
I worked on an interface upgrade for a while, but then found them already available, so dropped it.

Sometimes the original Mouse Trap is the best suited for the job.

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A Dalton