LED turn signals usually require an updated flasher to work properly. Most flashers require a minimum of 2 or more incandescent bulbs to flash correctly. That is 3.5 to 4 amps for proper operation. An incandescent turn signal bulb uses about 1.8 amps while an LED turn signal uses 0.25 to 0.45 amps. One incandescent bulb and one LED turn signal don’t draw enough amperage for the flasher to work correctly. They usually will turn on and stay on.
Below is a list of flashers that have worked with LED turn signals. You can cross reference these
parts to others that should work.
CEC electronic flashers
CEC electronic flashers will flash one or more LED lights. Negative ground systems only. Makes clicking sound while flashing.