I have led running lights on my truck (with a resistor already inline) and am encountering a flicker issue ONLY when the engine is running. I was thinking a cap would fix it.

  • Welcome to Motor Vehicle Maintenance & Repair! Is the flickering rhythmic? Does it speed up/slow down with the speed of the engine? – Pᴀᴜʟsᴛᴇʀ2 May 20 '19 at 1:36
  • How can you possibly propose a solution - like adding a capacitor - when you don't know what's causing the problem yet? You should do some troubleshooting first. Perhaps you would connect the LED's directly to the battery while the engine is and is not running for a start. Does it flicker when directly connected to the battery? Yes? Then it isn't the battery or the connecting circuit, but something inside the LED device responding to engine electrical emissions. No? Then something between the battery and the LEDs. – scorpdaddy May 20 '19 at 2:32
  • it could be that your altenator has an open or shorted diode. – Jasen May 20 '19 at 3:09
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    Paulster2 - Not rhythmic nor does engine speed affect it. It starts flickering after 5 seconds of KOEO. Scorpdaddy - I had stated that it ONLY flickers when the engine is running. Also, note that my "proposed solution" just so happened to work! I connected a 3300uf 16v electrolytic cap across the leads and the flickering is no longer an issue. My methods may seem a bit rash and or out of order to some people but I have been around the block a few times (53yrs old) and know what usually works for different situations. I was just having a "senior moment" and was not sure as to connec – Scott S. May 20 '19 at 7:12
  • Scott you should add an answer to this work the info of what you did to solve it, and mark it as the answer. It could definitely be useful for other users in the future. – kyle_engineer May 20 '19 at 16:38

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