Here's two links: a quick start guide and the full manual:
http://www.signalaviation.com/Flight_School/GPS/KLN89B/KLN89BQUICKREFERENCE.pdf
https://www.bendixking.com/servlet/com.honeywell.aes.utility.PDFDownLoadServlet?FileName=/TechPubs/repository/006-08786-0000_5.pdf
ASA has a trainer demo you can look at here (not sure if there's a free one on line)
http://74.125.113.132/search?q=cache:fQJcnlNERy0J:www.asa2fly.com/files/support/gpsdemoreadmefirst.doc+King+KLN89B+GPS+tutorial&cd=8&hl=en&ct=clnk&gl=us
Does anyone have suggestions for learning the King KLN89B GPS? The rental I'm flying has this unit installed (not new, but it works) and I'd like to learn it without having to fly for hours with an instructor. Are there any books, videos, etc that anyone knows about?