Led's draw very little power... There are basically two types of flashers. Standard and Heavy Duty or #of lamp specific and #of lamps I do not care.
The Standard flasher is rated for N lamps (Where n is an interger) and what it is is a self resetting thermal circuit breaker.. As current flows, the bi-metal arm in the flasher warms up, eventually like any self-resetting breaker it "Breaks" the circuit, then it cools off and closes and the cycle starts again.
The other of Heavy Duty or non, numer of lamp specific, works the other way around.
in this unit a fairly high resistance heater element is wrapped around a much heavier bi-metal strip.. When you activate the turn signals current flows through this heater wire,, IT IS NOT ENOUGH TO LIGHT THE LAMPS however... (With standard 1157 type lamps that is) as the heater heats the metal strip, eventually it CLOSES (Think an air conditioner thermostat) and shorts out the heater,, Now it cools off (Since the heater is not heating and the strip is low resistance)
With the first type the LED lights will come on full brillance and stay on
With the second they may be dimmer, but again they will stay on
The solution is a resistor.. This is a device you can buy at most any truck stop of auto parts store, it will have two wires and a metal housing with fins, may be colored or black.
one wire to the turn signal wire (Each side) the other to ground.. You may only need one per side. Depending on the flasher.
OR: in my case.. I simply left the front turn signals "Stock" only changed the rear to LED.
Home is where I park it!