On my 07 M/A the button was not handy. If you remove the dash gauge assembly the brain was taped to a brace along with the button and antenna. If not in this location try the panel next to the passenger seat. Otherwise you will need to remove the assist handle and short the wires.
2007 Mountain Aire,2014 Mountain Aire
2016 King Aire,2020 Newmar Essex
2017 Ford Explorer toad