PC Comms said:
I have a friend that currently has a set of halogen driving lights on the front of his truck and he wants to convert over to LED. It also has a Sho-Me multi pattern headlight flasher so that he can choose either flashing patterns or steady burn with the high beam override activated. I know that chances are the LEDs won't work without some sort of resistor being placed in line in order to be compatible with the regular flasher. Has anyone ever done this or can point me in the right direction as to what I need and, if it is a resistor, what size? Thanks in advance.
Is the flasher already controlling the headlights? If so, then adding LED's should not require a resistor. The current draw and resistance of the headlights should be more than sufficient to allow the flasher to operate properly.
If the flasher is one of the newer electronic-mechanical ones, it may not need resistors either even for just the LED's without the headlights..
If the flasher is solid state, but designed for halogens and incandescents, it should still work because it does not depend on sufficient current draw to activate the on/off. The downside is you will have slower flash patterns designed for halogens and incandescents.
The need for resistors alongside an LED is two-fold. If it's an old thermal electro-mechanical, it needs sufficient current draw to heat up the bi-metal switch. If it is a newer car with some type of computer control over the lights, it wants sufficient current draw to know that there is a halogen or incandescent bulb there. Not enough current draw with the flash activated creates a "bulb out" condition and thus the fast flash.
