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I put LED turn signals on my Jeep. Now my jeep thinks that the lights are burned out (which I was expecting). I ordered some 6ohm resistors so the car will think that there is a light plugged in. I would preffer not to use the load resistors because that would sort of defeat the purpose of having LED lights (using less electricity).

Is there any way I can reprogram my Jeep so that it does not flash quickly and stops showing the "burned out turn signal" warning?

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  • The resistors aren't that big of a deal, it's the energy loss due to heat from the filament bulbs that uses a lot of energy.
    – Nick
    Apr 17, 2013 at 17:58

3 Answers 3

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You probably need to change the flasher unit to match the load of the LEDs. If you can't find a custom part specially made for this, I suspect you can do it by replacing a capacitor inside the unit. This should fix the flashing rate, but I'm not sure whether or not it would fix the indicator.

Honestly, since this is just a turn signal, you might just be better off with the resistor. The electricity usage is pretty irrelevant unless you drive with your turn signals on all the time. :-)

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    I will do a little research on this. If it is simply an RC circuit then it should be no problem, but if it is controlled by the computer it will be more complicated. And yes, I could use resistors, but I would prefer not to waste 20watts on running lights - if I don't have to.
    – Sponge Bob
    Apr 15, 2013 at 2:28
  • Hopefully the computer is just monitoring the rate of the on/off cycle to give the indicator. If the whole cycle were controlled by the computer, wouldn't get faster like it's doing. Apr 15, 2013 at 2:30
  • I do appreciate the answer, but I did the math, and it is not a simple RC circuit. The measured values for what the capacitance of what "the capacitor" should be do not work out to the hypothetical frequency. :(
    – Sponge Bob
    Apr 15, 2013 at 2:51
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    Hmm, I always figured thats what flashers were, but maybe it's a type of circuit breaker that operates from heating up...? Apr 15, 2013 at 2:52
  • @R.. You are right, it does operate by heating up. That is why the flash is faster when there is less resistance in the circuit, less energy is dissipated in the circuit so it is consumed by the heating.
    – Ukko
    Apr 21, 2013 at 4:27
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Assuming that your Jeep has the same sort of clicky flasher that most cars do then you will need to add the resistor to make the circuit work. The reason is that the flasher is based on a thermal mechanism, it actually heats up a small wire that then twitches to break the circuit. When it cools it relaxes and closes the circuit this then repeats to make the flash. The reason that it blinks faster is that without the load from the resistor (the bulb originally) the heating happens faster, so to slow things down you need to add the load back into the circuit.

If you are trying to save a few electrons by leaving out the resistor, I suspect that you are losing any gains in the extra heating in the flasher.

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  • What is with the down vote?
    – Ukko
    Apr 19, 2013 at 3:20
  • He doesn't want to use a resistor.
    – Mike Saull
    Apr 19, 2013 at 14:40
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    @MikeSaull I know he said he did not want to use a resistor, but he also asked to reprogram something without a micro controller. There is no solution for the problem as he specified it, I and others were trying to explain why that is and maybe help find the solution that would work. If the problem is a total fear of resisters wasting energy, I hope nobody mentions how the blower motor speed is controlled :-)
    – Ukko
    Apr 21, 2013 at 4:35
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They sell resistor ballasts just for this application. Apparently you got a cheap kit if they did not include them. You have to put a big resistor with heatsink inbetween the LEDs and the power from the flashers.

Look around for LED resistors they shouldn't be too hard to find and adapt to your vehicle.

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  • Thank you for the answer, but in the question I specified that I would prefer not to use resistors.
    – Sponge Bob
    Apr 15, 2013 at 17:15
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    Oh sorry lol. That is the only way I know of. Otherwise you have to somehow disable the load sensing circuit of the blinker. Why are you concerned about the power draw of the lights? It's not going to improve your fuel economy at all.
    – Mike Saull
    Apr 15, 2013 at 20:54

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