Join Date: Feb 2017
Location: St. Louis, Missouri
BJ, the tool is Suzuki part No.09930-82720.
It's a small 2-position toggle switch with a 5" wire harness that terminates in a connector which is the mate to the underseat Dealer Mode connector. One could easily fabricate one with a small electronic supply store-bought 2-position toggle switch, some wire, and a terminal block w/terminals from Corsa Technica.com. But I'd rather just have one sent to me from Amazon.com for approx $20. This is the tool shown in the factory service manual.
There is a similar tool shown in the manual for ABS diagnosis, but they aren't the same.
My receipt for the tool shows total price as $19.95, and the supplier, through Amazon was Everett Powersports (425)212-2111 EverettPowersports.com