had exactly the same issue. started as drivers front, then I fiddled with it and lost both. then I had drivers come back and lost passengers. turned out it was my multifunction switch on the column. hope that helpsI haven't found this problem around yet but here goes.
On the way back home from the store the turning signal blinker started blinking fast so you figure that it's a blown bulb. I got home and changed the bulb and nothing was fixed. The left signal did not work but the parking lights worked. (GREAT ANOTHER 04 RL PROBLEM ) I started fiddling with it for a while and decided to change both bulbs from the Silverstar bulbs to the OEM and now both turning signals do not work but the parking lights do. I'm pretty sure I have checked all the fuses to see if it is any and I cannot find any blown ones. Any ideas?! Thanks.