One for the electrical gurus

RazMan

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I've got a strange problem with my LED headlights which I am hoping one of you guys can help me with.
The main beam idiot light comes on with both main beam AND dip! Testing at the light (LED by the way) reveals a good 12V when on maim beam as you would expect but when switching to dip it still shows 8V, which is why the idiot light never goes out. I assume there is some kind of back-feed between main & dip beams.
Is there any way to fix this? Maybe some kind of threshold switch (if there is such a thing?) that cuts the power to the idiot light if less than 10V or so?
As always, any help is very much appreciated.
 

Bigjaype

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It's thermal electrical leakage that diodes (your LED headlight is a big diode) tend to exhibit and it's enough to keep the blue LED lit. A resistor on the wire to the blue LED to drop the voltage and increase the load will work but you'll probably need a 1 watt resistor. I think 250 ohms.
 

Ishrub

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And then there is the 'idiot proof' trusty and reliable.......
1655796479859.png
 

RazMan

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I have just tried the resistor trick but no luck - the **** idiot light will not go out. I also tried another resistor which I had (50k) but still no good. I'm not really very good with electronics but will some kind of a hi-pass diode help?
 
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TURBO200R4

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I have just tried the resistor trick but no luck - the **** idiot light will not go out. I also tried another resistor which I had (500k) but still no good. I'm not really very good with electronics but will some kind of a hi-pass diode help?

first i would check to see when u change the hi/low switch that it actually changes to hi or low.
might b some feed back through that switch
i would start by taking the switch apart and checking the circuit one wire at a time hi circuit then low circuit
i have never done this i think that they say several springs r in there i do not know.
 

RazMan

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Yep, it is purely the 8V on dip beam holding the LED high. Strange that it didn't happen on the original clocks - the headlights work perfectly
 

TURBO200R4

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Yep, it is purely the 8V on dip beam holding the LED high. Strange that it didn't happen on the original clocks - the headlights work perfectly

i think i would still pull apart the switch and check the volts on that switch to see if it shorting across
that is my best guess
 

DEcosse

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Rather than Series, use a PARALLEL resistor between the high beam and ground - I'm guessing at value, but try 1K 1/4W; if that does not work try progressively smaller resistors - 470 ohms next still good at 1/4W; if you need to go smaller still, then you will need to increase the wattage accordingly.
 
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