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What diode do I need for automobile turn signals with LED's

  1. Jul 27, 2012 #1

    I have LED's all over my vehicle. I have them as tail lights, in the climate control,door switches, and several more throughout my car.

    I have this piece called a HYPERFLASH harness hooked up in the system that was recommended to prevent hyperflash, and it has done a perfect job. I just added what they call clear corners (turn signals) that have had LED's in them also with no issues. Yesterday I changed those corners for a set that had an LED strip along the bottom of the turn signal housing that has 3 wires that get hooked into the system:

    A ground, a lead for the parking light that turns the white LED's on the strip on when the lights are on, and another lead that goes to the turn signal that over rides the previous lead when the turn signal gets turned on and turns on the amber led's in the same strip.

    I now have hyperflash when I turn the lights off (for example, when it's daytime). ALL of my LED's inside and outside the car are now hyperflashing like a Christmas Tree. I was told that I needed to add Diodes to both the left and right side turn signal lead AND the parking light lead to stop the backflow of current.

    My problem is...I haven't a clue of which size, wattage, etc... that I will need. The car is 12 volts that can go as high as 14.4 volts and there are a total of 18 LED's (9 white parking light and 9 amber turn signal) in each turn signal (one on each side of the car). I was also told to run the diode along side the leads (tapping into the existing wires as opposed to cutting the wires and putting the diode in between the 2 cut wires).

    Any suggestions???
    Please advise
    Last edited by a moderator: Jul 27, 2012
  2. jcsd
  3. Jul 27, 2012 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    I'm not understanding what the Hyperflash does. It flashes LEDs or keeps them from flashing?

    Does it come with some application notes or installation instructions that show where the diodes should go? You will size the diodes based on the the forward current that they will carry, and the ~ 0.7V forward voltage drop. The product of those two P = I * V gives you the power that they will be dissipating. That determines the size diode that you will choose.

    BTW, are all of the lights street-legal, or is this just for car shows? Some lights aren't allowed to blink per the Vehicle Code...
  4. Jul 27, 2012 #3
    OK. Sorry. The lights are legal. The hyperflash harness STOPS LED's from flashing too fast when you turn the turn signals on.
    I have LED's EVERYWHERE in my car. With the help of this hyperflash harness, all systems worked normally like every other car.
    Now I installed my new corners with a two tone LED strip (amber for the turn signal, and white for the parking lights). I previously had normal corners with SWITCHBACK LED bulbs which worked perfectly. ( I have LED taillights, Climate Control, door switches, etc.. all over my car and have never had any issues until this new corner light). Enter the new corners with 3 wires (the previous bulbs fit into the new unit as it did the old unit) going to the strip that has been installed in the corner lights. One wire is connected to the turn signal that makes the amber led's light up when the turn signal is on (works nicely), the next wire connects to the parking light, which makes the white led's in the strip light up( it works perfectly), and the last wire goes to ground. ALL WORK PERFECTLY as they should. My trouble lies when I start the engine and do NOT have the lights on. All of my LED's inside the car and out start flashing. It all stops and everything goes to normal if I just turn on my parking lights or headlights. Then there is no hyperflash. It only happens with the car running and the lights off.
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