Bad ground (earth) on the rear light clusters. If the contacts will not clean up you may need to run another grounding wire.
check for a loose ground wire
If the lights come on but do not flash then the turn signal flasher relay is defective.
Replace the flasher relay if the lights come on but do not flash.
Check the ground wire for the rear lights in back underneath where it attaches to the frame/body/bed. It may be broken, corroded or loose.
bulbs are to small Check the fuses.
Usually this tells you that 1 or more lights are burnt out.
One of your turn signal bulbs is burned out. Either the front or the back.
On the back of a car there are tail lights, turn signals, and brake lights. Cars also have back up lights that tell people when the car is in reverse.
If the lights come on but do not flash, replace the flasher relay. If they will not come on check the fuses.
No, they do not have traditional turn signals but have flashing lights.
Try replacing the turn signal flasher
If the turn signal lights come on but will not flash you have a defective flasher relay. Replace the relay.