1997 Catera stays in Snow Mode

I test drove a catera today, loved it, except the snow mode stayed on, and would not toggle off. I shut the engine off, and turned it back on it was off. In case this isn't a standard option, snow mode puts the tranny in 3rd gear and slips alot, gradually gripping, to get you up a hill without skidding. Any advive on what causes it? When the snow mode iss on, the tranny ligth is on too. How do I get the OBD II codes for it? (97)
Any help appreciated!