One problem related to turn signal flasher unit has been reported for the 2004 Chevrolet Impala. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Chevrolet Impala based on all problems reported for the 2004 Impala.
1) events leading up to the failure - it all started out of the blue about 2 weeks ago. I have an intermittent failure of the blinker mechanism of the turn signals. When it does not work, the lever is turned for either left or right turn and the signal stays lit, but not blinking. Most of the time, thoughout the day, the signals blink properly. 2) failure and its consequences - this is obviously a safety issue in that drivers following me would not be as alert to a non-blinking light as they would be for a blinking light. 3) both myself and my local gas station removed and and reseated the possible offending fuse and associated relay module. He even indicated that both Chevrolet and pontiac cars have turn signal arms with shorts in them. I could not find any recalls indicating a short in the turn signals.