Last night I installed some 3157 switchback LED turn signals in my truck and having issues. I initially installed them without the resistors, and my vehicle did not 'hyper flash'. The lights would switch from white to amber as designed, but would start soon after stop switching back and forth or not come on at all after turning off the blinker. Even with leaving the blinker on, it will stop flashing properly after a while. I then installed the 50W (6ohm) resistors to see if that would help, but it continued the same way. The lights will function as designed when I first turn on the vehicle and function them...but after functioning for just a couple minutes the problems arise.

I am think the transistor/relay that switches the bulb from white to amber might be defective...as it is a Chinese product I bought off Ebay. After it is operated for a short period, the malfunctions start to occur. I left them in my vehicle to see if they would start to work, but when I arrived at work this morning 1 of the bulbs was completely off while the other was white (parking light mode). I'm thinking that maybe once the bulbs start to heat up from operation, a 'short circuit' develops. I've read online forums of people with different vehicles and bulb brand experiencing similar symptoms.

Are my assumptions correct or does my truck circuitry just not 'get along' with these types of bulbs?

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The resistors should make the truck's circuits happy. I would say your conclusions may be correct about the defective lights.

 

I just drove my truck to the gym during my lunch break, I drove with my headlights/parking lights on. When I started my truck, the white (correct color) was illuminated on both lights. I made sure to not even function my blinkers while driving (safe I know ). When I arrived at the gym just 2 miles away, one parking light was white(correct) and one was amber(incorrect). I guess the bulb just decided on its own that it liked being the color amber instead of white....I guess that is what you get with chinese bulbs.

Hopefully it is just a bulb issue. I will get a replacement set with the seller to see if the issue is resolved.

On a side note, at least I'm pretty sure that the newer Super Duty trucks do not require resistors when replacing the 3157 bulbs with LED lights. The truck only 'Hyper Flashes' when no bulb is attached to the socket.

 

I don't know about the newer trucks, but on the older trucks, that was the problem, the LED was such a low load on the circuit, the truck's circuits act like there is "no bulb". It was all in the flasher on the older trucks, as they worked on load, and you could buy a electronic flasher and usually fix it, or install the load resistors.

 

I finally got the switchbacks working on my truck. Usually resistors are only needed to resolve "hyperflash" issues, due to the leds not having much electrical resistance. The resistance of the leds I ordered are apparently enough to prevent my truck from experiencing hyperflash, so I did not see the need to use additional resistors.

With the leds plugged in w/o resistors, the amber blinker would work perfrectly, but the white parking lights would not illuminate. After a few emails with V-leds.com, they suggested that I try using resistors on the blinker side 'the high positive'. They mentioned that if there is ANY residual currently left on the blinker side (high positive), it will prevent the white leds from coming on. The resistor will help dissipate any residual current in the lines, allowing the white leds to work properly.

Well after installing the resistors, I'd have to say I'm a happy customer. Here's a couple pics