LEDs and capacitors/resistors

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GMC86

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86 GMC K1500 305 -
I am putting LEDs in all exterior lights. So far I have done everything in the tail light assembly. It's been working fine so far. Today I put them in the front flashers and now my blinker blinks very slow. Could this be a scenario that may be resolved by putting either a capacitor or a resistor into the circuit?
 

77 K20

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A resistor would work, but I'd just replace your standard thermal flasher unit with one of the "new" electronic flasher units that are built for LEDs.

The old thermal ones use a two different strips of metal soldered together. When you turn on your signal current runs thru it, it gets hot. The 2 metals expand at a different rate and warp. Warping then breaks the contact and your blinkers shut off. The metal cools and goes back to its original shape making contact again...

Your old light bulbs use a lot of current, so it works great. LEDs however use very little current so it doesn't work correctly.
 
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GMC86

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I've been doing some research and it appears that if my blinkers are flashing too slowly that I'm not getting enough power to the LED, which is saying a lot. I'm going to try installing load resistors on my rear LEDs and see if that might help provide more power to the other LEDs as I'm assuming they somehow are not allowing power to get to the other LEDs. I'm also considering looking into electronic flasher relays. Somebody correct me if my train of thought here is not correct.

P.S. I'm not sure why I mentioned Capacitors in the title. Disregard that please.
 

GMC86

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A resistor would work, but I'd just replace your standard thermal flasher unit with one of the "new" electronic flasher units that are built for LEDs.

The old thermal ones use a two different strips of metal soldered together. When you turn on your signal current runs thru it, it gets hot. The 2 metals expand at a different rate and warp. Warping then breaks the contact and your blinkers shut off. The metal cools and goes back to its original shape making contact again...

Your old light bulbs use a lot of current, so it works great. LEDs however use very little current so it doesn't work correctly.



Thank you!!! That makes a lot of sense. I'll try getting a hold of an electronic flasher relay and switch that out.
 

GMC86

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Okay so the load resistors worked. I installed them on the rear flasher LED's and now it flashes properly. No more super slow/non existent indicating. I believe what was happening was the LEDs restricted the voltage going to the flasher relay and it wasn't getting hot enough to bend the contact closed therefor it either rarely made contact or never made contact and closed the circuit allowing voltage back through to the lights. I found a video on YouTube that helped explain it pretty good.

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