This sounds related to a common problem, that I also had on my 2003 TL, with intermittent operation of the steering wheel audio controls. The buttons would intermittently work and not work. Sometimes holding down the down volume button would cause it to even go up!
The issue was addressed in TSB 03-015 where it describes how to remove the steering wheel and cable reel and peen/dent the copper ring. This causes the ring to better contact the steering shaft that passes through it. The forum won;t let me post a real link, add periods(dots) to the one below.
www mdxers org/forums/attachments/problems/24697d1095748088-any-new-info-tsb-steering-wheel-controls-sb-10001341-7274.pdf
There was a much better photographic DIY tutorial available for this procedure. But, all links to it, that I could find, have been removed.
From my own experience the only things to be careful about were, exhibit extreme and due caution with disarming and removing the airbag! Also, the copper ring is very soft, it takes very little pressure to dent/bend it so, start with very little pressure and build slowly.
Edit: I found the How-to document www freefilehosting net/remoteradiofix
