LED Load Resistor
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=145655
Printed Date: April 26, 2024 at 6:45 PM
Topic: LED Load Resistor
Posted By: shezza
Subject: LED Load Resistor
Date Posted: September 28, 2019 at 3:11 AM
I have a 2012 Audi A6. I've replaced all the interior globes with Philips LEDs. After switching the car off, the lights were all flickering. I installed a 49ohm resistor in parallel across one of the connection and it seemed to solve the issue. Almost! As it created another issue. When the car is off, the LEDs will only subtly light up. No where close to full! I suppose I need a lower resistor value? If so, how do I find out what that value is without buying multiple resistors? TIA
Replies:
Posted By: geepherder
Date Posted: September 28, 2019 at 6:01 AM
If it's like my old Saab, the flickering is caused by modules pulsing the bulbs to see if they are burned out. My solution was to use relays to power the LED's.
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My ex once told me I have a perfect face for radio.
Posted By: shezza
Date Posted: September 28, 2019 at 7:33 PM
I understand it only monitors exterior globes. That is why I am not getting an error message for any interior globes, only the exterior ones I changed. I have not put a multimeter to it, though I am guessing there is still a minute amount of power going to it which is not enough to power a normal globe, though enough to get an LED flickering...
Posted By: eguru
Date Posted: October 03, 2019 at 6:55 AM
shezza wrote:
I have a 2012 Audi A6. I've replaced all the interior globes with Philips LEDs. After switching the car off, the lights were all flickering. I installed a 49ohm resistor in parallel across one of the connection and it seemed to solve the issue. Almost! As it created another issue. When the car is off, the LEDs will only subtly light up. No where close to full! I suppose I need a lower resistor value? If so, how do I find out what that value is without buying multiple resistors? TIA
I can't make a specific recommendation for each bulb in your vehicle but you can calculate the ideal resistor value yourself. Check the current draw spec for the original bulb then subtract the current draw of the LED replacement That will get you the current that should be flowing through the shunt resistor. Calculate the theoretical resistance from ohm's law and then multiply that by about 1.5 - that usually cures any "hyperflashing" issue on exterior lamps and should definitely shunt the off-state leakage current from your BCM.
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