if the front signal is working and the back doesn't, the light is probably blown.
Either the front or back turn signal bulb is out
front bulb blown
check and make sure all the lights are on like if a turn signal is out in the front then the signal will stay on in the back when you turn the turn signal on.
flasher will not flash when circuit is open or shorted replace left front turn signal bulb
Remove the wiring harness from the back of your 1991 Chevy Corsica turn signal. Remove the turn signal retaining bolts. The entire turn signal will come out. Reverse the process to install the new turn signal.
One of your turn signal bulbs is burned out. Either the front or the back.
The turn signal light can be accessed from the back of the turn signal light assembly. Push the lightbulb connector in and turn at the same time. The lightbulb will come out and can be changed.
try the turn signal switch, the connector on it, the connections to the signal lights, the wiring, etc. On some vehicles, the turn signal switch controls front and back blinkers separately
Turn signal switch has 1 hot wire per ea. side.
Could be turn signal flasher
One or two front turn signal bulbs is busted. Check your front turn signal bulbs and replace it.
Probably needs a turn signal flasher