I purchased duel filament replacement LED bulbs for my 2004 F150 rear tails. They only blink on and off. I tried them in my chryler 300. They blinked faster, but worked. Why not in truck?

 

Some vehicles have flashing units where they require a certain power draw to activate the flashing sequence.

Usually LED tail light assemblies will have a resistor pack included to make them work.

 

Get some 6 ohm resisters from ijdmtoy.com or a autoparts place. go from high power side (blinker wire) to the ground side (black wire). This will pull any current left from the blinker circuit so the running lights will come on.

 

Ok we need schematic.....Please

 

I'm posting from my phone so maybe someone else can pitch in. It's really simple though. The taillight bulb has 3 wires. Ground, low power (running light) and high power (blinking light). Just tap into to blinker wire and ground wire and your good. It's going to be the 2 outside wires that come out of the plug. Leave the center one alone.

 

Be careful for where you place the resistor for those LEDs too. They are known to get very hot. Hot enough to melt plastic at times. So... away from fuel lines, other electrical, and somewhere it will cool itself off.

 

I have some for my switchbacks and they get a little warm but I don't think they would get hot enough to melt things. And there are no fuel lines by the tail lights so no worry there. Air moves through that area behind the tai lights while driving anyways.

 

I have resistor packs in plastic cases, and they barely get warm to the touch.

I think if you got real bad heat, somethings wrong.

 

It all depends on the type of resistor and what it is rated for. A crappy off the shelf typical resistor might not be suitable to handle these bulbs, especially if there are many leds run in parallel. I'd err on the side of caution anyways and still mount it off to the side.

 

The resistors I use. They say they do get hot but mine just get a little warm to the touch.

http://store.ijdmtoy.com/50W-Load-Re...d_resistor.htm

 

Well, if they really are 50 watt, that's at least good design practice. Resistors should run at about half their rating, and 12 v x 2 amps ~ 24 w.

I have read elsewhere that they make LED flashers that run on the lower load. Unless they use this same trick internally, that might be a better deal -- provided that they're reasonably priced.

just a thought,

hj