First I attempted entering the config mode with the game running by holding "Options" and "Share" buttons, then hit the PS button so the Crosshair icon flashed blue, tapped the square button and then the downshift knob. Then I pushed the "Options" and "Share" buttons again to exit, and tested.
When this did not work, I hooked the Crosshair up to my laptop, plugged the driving wheel into the Crosshair, entered the key mapping screen, selected the square button and hit the downshift knob. Here I was able to watch the key binding update to J46. I saved the new settings, tested in game, and the same issue persisted.
Thanks for any help you can offer!