I don't even know if my auto-cancelling feature works, I just hit it after making a turn. A broken fuel sender keeps my fuel gauge from registering too.
Wish I had some deep insight to offer on using a multimeter in order to analyze your relay and/or switch. Getting in the habit of turning the blinker off manually is guaranteed to help you avoid spending the $60 though.
Ben C - Cary, NC
2001 XV1600A Road Star
2003 XVS650A V Star Classic