LED shift light

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mefmotorsport
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ECU Model: S100 Pro
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LED shift light

Post by mefmotorsport »

We wired up a 10mm ultra-bright white LED for a shift light. It came with a resistor pre-wired in series (don't know what value).

Although it works fine and is nice and bright we noticed that it glows all the time when the ecu is switched on which is quite annoying, especially in the dark.

I assume its due to a small leakage current through the driver in the ecu causing the LED to draw enough current to light it.

I solved the problem by putting a 100 ohm resistor in parallel with the LED/resistor combination (ie a "pull-up" resistor)

Just thought I'd post this as a simple solution in case any others had had a similar problem.

martin
Antral
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Re: LED shift light

Post by Antral »

mefmotorsport wrote:We wired up a 10mm ultra-bright white LED for a shift light. It came with a resistor pre-wired in series (don't know what value).

Although it works fine and is nice and bright we noticed that it glows all the time when the ecu is switched on which is quite annoying, especially in the dark.

I assume its due to a small leakage current through the driver in the ecu causing the LED to draw enough current to light it.

I solved the problem by putting a 100 ohm resistor in parallel with the LED/resistor combination (ie a "pull-up" resistor)

Just thought I'd post this as a simple solution in case any others had had a similar problem.

martin

Yes Martin some people do have that problem it is as you say a small current leakage I believe.
PhillipM
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ECU Model: S80 Pro
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Re: LED shift light

Post by PhillipM »

I use the same solution for alternator field lights if I switch to LEDs, works great there too!
stevieturbo
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Re: LED shift light

Post by stevieturbo »

Even my 12v bulb did the same when I had one..was never bright enough to annoy though, but can easily imagine an LED being a lot brighter
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mefmotorsport
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Re: LED shift light

Post by mefmotorsport »

stevieturbo wrote:Even my 12v bulb did the same when I had one..was never bright enough to annoy though, but can easily imagine an LED being a lot brighter
I can't see why a 12v bulb would glow when the driver is not switched on, i wouldn't have expected enough leakage in it to do that!

Any way it works perfectly in sunlight but is blinding at night! needs some kind of shield on it!
lumley32
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Re: LED shift light

Post by lumley32 »

basically the more current a transistor can switch the more leakage you will get when its "off" i happen to know that the outputs on the DTA Ecus can handle far much more current than they advertise (in fact all the paper work got downgraded a few years ago).

i haven't ever measured the leakage current but it is enough to light a small filament lamp, depending on witch output your using.
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mefmotorsport
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Re: LED shift light

Post by mefmotorsport »

yes, that's very true the shift light driver is just like an injector driver so I can see why this happens.
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