2001 Chevy Impala. Blinkers only work occasionally. I suspect it has something to do with the tilt steering causing a short in the connection. Just bought the car and trying to work out some of the bugs.
Do you emergency flashers work? If not I would suspect a bad flasher.
GM multifunction switches (turn signal, cruise, wipers, etc) from this era have a higher failure rate. I had to replace the multifunction switch on my 2000 Blazer a few years ago.
The part is ~$200 and expect a few hours of labor for the repair (~400 to 500 total).
Before I replaced the switch I spray CRC Electrical Contact cleaner into the base of the switch at the steering column while working the turn signals to clean the contacts. This fixed the switch for a few days and verified the switch was the problem.