It's probably your hazard warning switch (flasher unit). The turn signals are wired through it so when they start 'misbehaving' it is often the result of a flasher unit gone bad. The fact that your turn signals work again, albeit shortly, after you activate the warning switch is an indication of that.
I replaced that flasher unit/switch on a 03 impala and it wasn't much work at all, but I've never done it on an 05. I don't think it's any different though.
If I recall correctly the switch was around $50.
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Wednesday, December 19th, 2012 AT 8:01 PM