Okay, so my Mom's Buick had a left rear turn signal out. I replaced the bulb. Since we had everything open back there, I went ahead and replaced the right rear turn signal bulb, too.
The left signal went back to working fine. The right one started to malfunction slowly. Sometimes it would work, other times it would flash fast like the bulb was out.
After a little while (a week or two) I chanced the right side bulb again.
The right side started to work fine, but the left side started to malfunction...sometimes it would work, other times it would blink fast as if the bulb was out. (sometimes within the same use... we could be sitting in a left turn lane with the blinker on and it would start off fast, and then start working before we made our turn). Now it has been about a week and a few days since I replaced the right side bulb and the left side almost never works.
I will be triple checking to see if it's possible to but the bulbs in backwards, but it appeared to be impossible... like the bulb was made to work either way you put it in. A friend has suggested that it might still be possible to put the bulb in backwards and I should check one more time. If i did get it in backwards, then it's working with the filaments switched... when we use the blinker it's working off the break light filament and vise verse. That would make sense because the bulb would burn out faster since it's not being used correctly, but since I was already concerned about this and checked it out, I will be surprised if that is the case. I am going to check it again anyway though when I go over to my mother's today.
Has anyone got any other suggestions?