wow no year?
the operators guide , this info is missing , and so is suzuki here.
some had the 6380 radie others 6400 in 2007
is it the
Press BND/AST button about 3 seconds, three minus sign appear on the display. Use button 1 to set the 1st digit of the code, every time you press '1' the digit grows, then use '2' to insert the 2nd digit, and so on . After inserting all the digits, press again BND/AST 3 seconds to confirm the code and, if it' s the right, the radio is unlocked. The number on the left of the four '----' is the counter of times you made to enter the code.
2008 answer again 4 radios offered including XM sat.
page 4.55 (see link and end for free lost guide)
or pay 4 bucks and replace your lost oper guide?