I have a 2004 Ford F-150 Screw XLT 4x2, I have just now decided to make the swap to LED. I purchased a set of Lasfit 3157 RED LED's and a set of the same in Amber for the front. The Amber LEDS have not arrived yet. I also bought the EP27 Electronic Flasher. I'm not having issues with hyper flash or with my cruise control. Everything works fine in that regards. The issue I am having is when the key is on, lights on, the rear LEDS are at full brightness. I have no tail lights per se, they are bright on and off the brake and they are also causing my LED 3rd Brake light to light up even when the brake pedal is not depressed. I haven't replaced the fronts yet so I don't know if a mix of incandescent and LED's is the issue or if I am having some sort of feedback through the circuit. I have some load resistors that I haven't even opened the package on yet. I'm looking for someone who has experienced this same issue when installing LEDS in the factory housings. Curious if I still need to use the load resistors even though I have the electronic flasher to prevent voltage from feeding back through other circuits. I have searched Google and only found one person with this same sort of question but there was no answer. I tried to explain this issue the best I could. Hope someone has some insight on the problem and how to resolve it.

 

I have all led bulbs on my 2004,all I did was connected the resistors and bulbs I also have some other experience with leds. I would connect the resistors and see if that fixes the issue if not we’ll go from there but that’s most likely the problem.

 

Thanks. I'll give it a try as soon as my front LED's come in. I have 4 resistors. I'll report back when they are installed and see how it goes.

 

I had a led bulb swap several months ago on my 05. I used all JDM and the EP27. I didn't use resistors, and I didn't have the issue you are having. The only issue I had was the loss of the cruise.

I now have a full led tail light housings and third brake light housing with no issue.

It maybe each brand has it's own flaw, and hopefully the resistors will help.

 

Don’t use resistors on these trucks. There’s no point in splicing the wiring if you don’t need to. Replace the flasher unit.

That said, I know some of the Lasfit leds come with build in resistors. Do you have that style or the non resistor type? How do things work when you remove the EP-27 flasher and put the OE unit back in?

ive used led in my truck for years and haven’t had issues. Sylvania zevos all around and a Novita EP-27.

 

 

I have my front LED’s now. I will install all 4 this evening and see if I’m having the issue I was having before trying any resistors. With and without the factory flasher relay and EP-27.

 

Ok, I have all 4 LED's installed and everything works as intended with the exception of one thing. Key on, lights on, I have constant brake lights, no tails. Key off, lights on, I have tail lights and brake lights when the pedal is depressed. It's still lighting up my 3rd brake light key on, lights on even though brakes are not depressed. Everything works fine as it should with incandescent bulbs. What am I missing? The Factory Flasher relay and the EP27 behave the same in regards to the constant brake light issue. I did notice with the factory flasher relay that instead of hyperflash when activating the turn signal, it just buzzed. It only when into hyper flash when I activated the hazards. (My third brake light is an aftermarket LED unit)

 

I'd try a different led bulb.

 

Ok, by installing a load resistor on the rear left and right brake/signal wire and ground, all my issues have gone away. Now to figure out why my brake lights turn on when I plug in the lights from my cargo rack. Ugh. Lol.