Thanks for all yore help, guys

It's the diagnostic plug alright.
While searching the web for an answer, I ran into this PDF file:
http://www.carsoft.ru/avtorepair/suzuki2.pdfAt page 4 (Fig. 3), you can see the plug.
The file contains a lot of info, that I think you all can find it handy.
BTW, in the file they are referring to 2 types of Sidekick, TBI and MPI.
what is the difference between them?