I have an issue with my 1992 Astro van. The turn signals work perfect when the headlights are OFF. At night when the headlights are ON the left turn signal lights up but it will not flash on and off. I have changed the flasher and it did not fix the problem. Has anyone else experienced this? Any help would be welcomed.

 

You probably have a problem with the sockets for the bulbs on the left side. It could be either at the front or rear.