not enough info to answer properly. Please ask a new question with year, make, model of the vehicle.
Check fuses, bulbs, flasher, switch.
if the front signal is working and the back doesn't, the light is probably blown.
Check bulbsCheck fuseCheck turn signal flasher
Defective flasher.
Either hand signal or check and replace your fuses and turn signal bulbs.
replace turn signal flasher
Your "turn solenoid" is defective.
Did you happen to check the turn signal flasher before you installed the switch?
do you hear clicking noise -as if the inficators were working? If not then go check the flasher relay and its connections.
Bad turn signal flasher? Bad turn signal switch? Blown fuse? Bulbs burnt out?
Trun signal lights do not come on at all not on dash or outside
One of the signal bulbs may have burned out.
2002 ford explorer turn signals not working