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LED Ghosting and solution

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#1 OFFLINE   notquitesane


    C-Max Hybrid Member

  • C-MAX Hybrid Member
  • 92 posts
  • Region:Canada Prairie Provinces
  • LocationEdmonton
  • My C-MAX's Year:2015
  • Current Vehicle:C-MAX SEL 303A

Posted 03 May 2015 - 04:49 PM

I've had my C-MAX for a week and I've already replaced a bunch lights from incandescent to LED.   I don't know i you guys know about LED ghosting, but when the LEDs are supposed to be off, there is still a tiny bit of current left in the circuit to cause the LED to glow very faintly.  I just ran into this with my licence plate lights and my high mount center brake light.  Might be happening with others, but I haven't been looking that hard.


I used 194 LEDs from Diode Dynamics, the HP5 (brighter) version for the center brake light, the puddle light and signal light in the mirror and I used the HP3 (dimmer) version for the licence plate lights.  When it was darker outside, as soon as I unlock the car, the parking lights come on and I saw a couple of the LEDs in the center brake light start to faintly glow and flicker.  After I lock the car, they would continue to do this for quite a while.  I learned that putting a 1K ohm resistor in parallel with the LED bulb will prevent this phenomenon.  It allows the trace amount of current and alternate path, preventing the LEDs from glowing and flickering.


In the attached picture is where I put the resistor for my center brake light.  No more flicker/glow!


I just shoved the resistor in friction fit for now.  It was threatening to rain on me when I was doing this.  I'll secure the resistors better, but it solved the issue.  

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#2 OFFLINE   vonsche


    New Member

  • C-MAX Hybrid Member
  • 13 posts
  • Region:U.S. Pacific Coast
  • LocationHillsboro, OR.
  • My C-MAX's Year:2016
  • Current Vehicle:2016 Ford C-Max SEL

Posted 26 October 2017 - 06:44 PM

I noticed the same thing.  Researched it on google and it said that its the solid state relays in newer vehicles.  If you wait 10 minutes the car shuts off all electrical power and that ghosting goes away.  I tried several LEDs in the lic plate and noticed some are worse than others.  Probably because some have more resistance.  Sure enough I went out there in a little bit and the "ghosting" was gone.  Probably some expensive LEDs that will adjust for this out there.  I don't mind it, most of the time I'm parked around street lights anyway and you can't see it.


This was from a Jaguar forum:

Hi...not to worry. This is because Jaguar (and many others) have converted from normal electromechanical relays to solid state relays. Solid state relays don't completely cut off current flow. when you install LED's, there is a diode effect that causes a very small amount of current to flow. I converted my 2009 to 2011/12 style taillights and all LEDs for exterior lights, and see this effect. As soon as the (10 minute?) period where all electrical flow is cut off, they'll do that. After 10 minutes will quit. No harm to battery or circuit (I replaced AGM battery about two years ago, still going strong). Regards...ct

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