Is this possible? can wires to a fixture (bulb socket) get reversed so that the low power filament of a dual filament is used for the turn signals rather than the side marker lights? If so, I thought the wires are in place?
Get a wiring diagram of the car. Auto Zone may print one for you.
A bad ground will make it seem like the wrong filament is coming on. It can even make both filaments glow (at reduced brightness) when only one should be powered.
How many threads are you going to start on this one problem? You would get better advice if you put all the information and questions in one thread.
I would also suggest it is possible for a dual filament lamp may have an internal short and it may act like that. Get a couple of new lamps and try them out. It may be that simple. Just because a lamp works sometimes does not mean it is not defective.
However if you give us more details about your problem, it may help us help you. What works as expected and what does not, and how not.
Dual filament bayonet style bulbs have two little dots of lead in the bottom, one for each filament. The brass base is the ground. On the brass base are two little nibs, one higher than the other. It’s possible to push and turn the bulb into the base the wrong way. The bulb will still work but the wrong filament is coming on for marker and turn signal. Take the bulb out and note the location of the nibs, then look in the base to align them properly and the lights should work correctly.
I see the condition you describe all the time. Someone has forced the bulb in the socket and now the turn signal light is lit when the headlights are on; very common.
Well stated. Been there, done that. It’s also possible, with some bulbs, in a loose bulb for the wrong contact to be touching and the wrong filament energized. Done that too.
update on my annoying left turn signal problem…thank you guys for all your advise!!! much appreciated!!! and thank you richw46 for your explanation of the nibs on the side of the bulb. Through my research online, I only found one web site that mentioned the nibs on the bulbs and that was for led bulbs. Apparently I put the bulb in wrong. Since the bulb worked in the sense that the side marker light worked correctly and the turn signal was dim, I thought the bulb was in correctly. I took out the bulb and tried to align the nibs. On the second try, everything worked perfectly. The turn signal, hazards, and turn signal when headlights are on work as they should. Also, the fast blinking is gone outside the car and on my dashboard. Thank you guys so much…saved me a trip to mechanic…I guess it pays to be persistent on car talk 
Glad to hear you got the trouble figured out. Thanks for the update. In the future, if you start a thread about a problem it is best for all involved to post to that original thread only. Don’t start another thread. That way all involved will be able to see what has been going on for the solution of the trouble.
thanks cougar!!! I’ll definitely stick to one thread for a problem…beer on me for all those that took time to reply;)
Skip my beer. Instead, drop a turkey off to a needy person or organization this holiday season. Pay it forward!