Turn signal issue

88 Limited. The driver side turn signal is acting up. Passenger side works fine. Sometimes it doesn't blink at all, sometimes it blinks, but very slowly. Also the front one doesn't light up when the headlights are turned on. I replaced the bulb yesterday with no luck. I was thinking maybe the flasher unit in the fuse block, but that wouldn't explain why it doesn't light up with the headlights. Bad ground maybe? Any thoughts?

On my 87 -it turned out the socket was bad,,,,the metal contacts had rusted away.
Replaced socket,all was good

Same on my 88 MJ. Replace your socket.

x3.

the old style sockets have the ground exposed on the front, it gets nasty. Then it grounds through your dash indicator lamp and does wierd things.