Verified answer

See if they work properly when you rev the motor. Most turn signal problems are due to a low battery.

If the bulbs are good, but some lights don't come on, the only possible reason is a lack of electrical continuity--either open wiring or corrosion at the bulb socket or at a connecting block somewhere. Don't forget to confirm that there is a ground at the turn signal, as well as power.

Put new light bulbs in the rear.

When bulbs burn out it screws up the load equalization and causes the flasher not to work.

There , your problem is solved for like 3 bucks.

If you are running LEDs then the controller that came with them has a prob. That is if all the wiring is correct and everything is grounded correctly.