Newbie here. I know this is an old topic, but thanks to your posts I have been able to fix the light switch on my 2006 Yaris, saving $350! I had to take out two screws from behind the steering wheel (by turning the steering wheel 90 deg. clockwise & anticlockwise from centre) but was then able to gently prise off the top cover from the steering wheel housing. No easy way to take off the bottom cover so I left it in place while I gained access to the light switch connections and gently sandpapered them.
Thank you, particularly to the following members: