In my 2011 28.5RLS its under the shelf the TV is fastened to on the left hand side of the cubby hole. It's towards the rear and you might need a flashlight to see it. Not a very good design.
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There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
Thanks RVhiker you were right on. It was where you indicated in the back behind a cable, needed a flashlight to see it. Also just a button, no small red light. This is my 5th rig, all the other switches had the light to indicate when they were powered up.