For a 2011 Solera, the rear parking, turn, backup and stop lights are controlled by a printed circuit board assembly located toward the front of the vehicle above the sewer hose cabinet in the left rear of the coach. It is behind a fabric covered cover held in place by a single screw nearest the access door. The board has fuses on it (but they are not what goes bad - in my experience).
The board (module) itself fails for the parking circuit. The parking circuit has 13 light bulbs on it (5 front on the top of the coach, 5 in the rear on top, two side clearance lights at the rear and the license plate light).
I am nearly certain it is because of the high inrush current for incandescent bulbs and having so many of them on the circuit. Incandescent bulbs have nearly NO resistance when they are off and the filament is cold. The instant an incandescent bulb is turned on it draws about 10 times the normal operating current. With 13 bulbs on this circuit there is a ton of inrush current - about 130 times the normal current. The current does not last long enough to blow the fuse, but it does last long enough to blow a FET (field effect transistor) or a normal transistor (don't know which the board uses) on circuit board driving the lights.
My I received a new board and installed it yesterday AFTER buying new LED lights and removing the old incandescent ones. Replacing the board one must be careful as the board has a 12V supply from the coach providing power to the board (plus a ground terminal with several ground lugs and then 3 connectors. One 5 (or 6) pin connector for supplying inputs or signal wires from the coach), and 2 connectors, one for the signal / stop lights and one for the backup, and tail lights. DO not let the 12V supply touch any other wire or the metal board cover. Someone that was good would have found the fuse supplying the 12V to the board and remove it but I'm too lazy and I was just VERY careful taping the end of the 12V lug after removing it).
I replaced all the bulbs (except the license plate bulb) with LED's. The lights not only last forever, they do not have "inrush current", they draw the same amount of current all the time.
The LEDs I used were less than $1 each for the bulbs - 2 bulbs for under $2 - here is the link:
Note - these LEDs are polarized meaning that if you put them in backwards they do not illuminate. So in replacing them you need to make sure they are in the right orientation (rotated properly in the socket).
To insure I did not blow up the new board and correctly oriented the polarity (rotated the bulb) used the following procedure:
I pulled all the old bulbs out (but 1), started the vehicle, made sure the one light was on. Then pulled that bulb out with the vehicle on, installed the new bulb rotating it as necessary to make sure it was on (getting the polarity right). I then repeated the installation process for all the lights, turning the vehicle off once all the lights were replaced and working. I did it this way - removing all the lights before using the new light control PC board - to make sure I did not ruin the new board.
We love our Solera!!!