You didn't indicate where you are located (something generalized like "Nebraska" in your profile will help) so I am hoping that you live in the US.
That said, take your Sidekick to an AutoZone, have them hook up an OBDII reader and get the codes that are being thrown by the system.
It is a free service.
I did it on my '96 Tracker and found the info helpful.
The "Is it upgradeable" comment at OBD2.com is probably a "CYA" note. You can further research the comment (which actually may not apply to your 'Kick) by visiting your local Suzuki Parts Counter/Service Department or you can take it to AutoZone and see what happens.
EDITIf you check out the OBDII section at
http://www.suzukipitstop.com/home/home.asp, you might better understand the "upgradeable" comment. Apparently, you (the purchaser of the OBDII hardware/software tools available from Suzuki) can modify/upgrade the ECU on many North American Suzuki vehicles. Whether this includes your 'Kick is uncertain.
So, the table at OBD2.com is not talking about upgrading the OBDII reader itself but about upgrading the vehicle's ECU programming - something that aftermarket performance folks are doing through their "chips". Plus, if you had to modify the reader, it would be a mod that would not effect how the reader works on ALL the varieties of OBDII vehicles that these readers work on.
Remember, all a reader does is turn digital code information into a form that you can read - a big improvement over deciphering the "Check Engine Light" blinks.
Thus the CYA (
Cover
Your
A$$) comment...
END EDITHope this helps!