I had an issue on my Ford truck where the right rear bulb had burnt out and the loose filament shorted to the opposite filament. The result was when the lights were on, the right turn signal would not flash, but was on solid. I was on the road with a camper and it took me a few days to get the opportunity to take the camper off to access that bulb. In the meantime, I signaled right turns by "manually" flashing with the turn signal lever.
I would double check the bulbs to be sure that one or more filaments aren't shorted together.
