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12Pin DRL Flasher Relay LED Modification (Another One)

Discussion in '2nd Gen. Tacomas (2005-2015)' started by jad3d, Aug 19, 2016.

  1. Aug 19, 2016 at 12:56 AM
    #1
    jad3d

    jad3d [OP] Well-Known Member

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    Right off the bat many thanks goes out to @VE7OSR for validating the resistor value I needed. Based on his information hopefully others who are inclined can find the right resistor for their situation.

    My 2010XR came equipped with DRL's. I stuck with incandescent bulbs for the longest time with no issues until my first set of headlights had their lenses melted by the DRL.

    After purchasing new headlights I set out to prevent the lens melting again and decided on using LED bulbs instead. LEDs present a well known problem of hyper flashing.

    To fix this issue I originally installed the 6Ohm 50Watt load resistors. 4 total (one for each signal position; 4 LED bulbs replaced; front and back).

    This solution worked for the hyper flash but it didn't provide the bulb out hyper flash.

    To get the bulb out hyper flash back I decided to modify the DRL flasher relay. Others have done this by grinding the shunt to fix the hyper flash but I personally didn't feel like playing guessing games on this. Another factor I considered was if I should ever need to go back to incandescents I couldn't use the modded relay...I would have to buy a new relay.

    Since I would have to buy a new relay in the event I may need to, I figured I might as well buy a new one and modify that for LEDs and retain my stock relay for incandescents. These relays, new, aren't cheap but if you want to have the ability to return to stock quickly this is the better route.

    Another way to retain stock function is to remove the stock shunt in its entirety and keep it in a safe place.

    To modify the relay with resistors (as opposed to grinding) you need to determine your LED amp draw.

    Since I was using the same bulbs (Sylvania ZEVO 3157A and 3157R) for the front and back, I simply needed to verify the amp draw of one bulb.

    My reading put one bulb at roughly 115.6/7 mA. Rounded up to 0.116A.

    Courtesy of @VE7OSR
    Alot of numbers there but the key numbers are the amp draw of the bulbs (117mA), the voltage drop across the stock shunt (0.075V), and the minimum voltage used to determine a bulb out scenario (0.049V).

    The voltage drop and minimum voltage values, through research, pertain to the 12pin drl flasher relay (with one shunt) per @VE7OSR https://www.tacomaworld.com/threads/12-pin-dtrl-led-flasher-modification-2012-tacoma.244028/
    Wow that was alot of information to get through. The quick and dirty is that you need to find the proper resistor value to match your LED amp draw to allow enough voltage drop for the circuit board to do its job and see a proper load for bulbs working or not.

    So for my situation I ended up using (due to available local stock) a 0.33Ohm 2Watt resistor for 4 LED signal bulbs (two front; two back). After a week of driving every day (modded/installed the relay on 12August2016) my signals do not hyperflash, I no longer need "hot" resistors wired in parallel, and the bulb out hyper flash works when disconnecting one bulb from the circuit.

    Overall I am happy with the outcome and hope this information helps others in the future.

    There are many existing threads and pics on the relay location and removal so I will only add the pics of what I have done to this point.

    It took me less time to remove the stock shunt, solder the new resistor, and connect the relay back into its harness than it did for me to wire 4 resistors. I also ziptied the relay to a spot out of the way but easier to get to than the factory location.

    12Pin (2005-2011) DRL flasher relay part number
    [​IMG]

    Stock shunt removed
    [​IMG]

    Solder point on the underside of the board
    [​IMG]

    Resistor installed
    [​IMG]
     
    YOTA LOVER and DistortedAxis like this.
  2. Aug 19, 2016 at 9:05 PM
    #2
    caribe makaira

    caribe makaira Well-Known Member

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    Hood Struts, My version Fogs always ON, Map & Overhead Light Mod,
    So what happens to this resistor when you connect a trailer light converter to this circuit and add more led's.
     
  3. Oct 30, 2016 at 10:05 PM
    #3
    VE7OSR

    VE7OSR 'interfering with Natural Selection since 1990'

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    Armour: All-Pro Skid plates - IFS, transmission, and transfer case. Pelfreybilt rear standard plate bumper, Metal Tech Sliders w/ kickout and dimple die filler plates. Front Suspension: OME 885 + NitroCharger 9000 shocks + 1/2" spacers for a 3" lift. Superbumps replacing stock bumpstops. Camburg ball joint UCA SS braid brake lines Future: ADS Extended length, extended length UCA BJ to increase droop capability Rear Suspension: All-Pro Expedition rear leafs, Walker Evans 27" rear shocks, extended rear brake lines (Wheelers Offroad), U -bolt flip kit, rear Timbren bumpstops. Future: Hammer Hangers, Shock relocate, ADS 12" or 14" shock. Interior: Weatherteck floor liners - front, Wet Okoles- front, ScanGauge, LED interior & map lights. Power moonroof. Exterior: Raider Cobra canopy, retrofit headlight by Insight, LED bulbs all around, modified flasher unit for LEDs. Rear diff breather mod. Front diff vibe problem, driver's side needle bearing replaced with ECGS bushing. yet to install: HID Blazer Fog Retrofit, LED Flood & Spot, + switches, fuse panel. swaybar relocate blocks (build my own)
    No change. The lights for the trailer are operated through relays. No further modification needed to the flasher unit, as the relay coil load is always part of the flasher load. The flasher only 'sees' the relay coil, not the actual current draw of the trailer lights.

    ah, I see your thinking of adding an aftermarket versus using the stock trailer circuit.
    In that case, yes any added load from the aftermarket unit would need to be taken into account, but i suspect the wiring for the trailer option is probably already on the truck, just need to add the relay in the engine compartment, and find the trailer harness connector by the bumper.
     
    Last edited: Oct 30, 2016
  4. Nov 5, 2016 at 8:05 PM
    #4
    2ndchancetoyotas

    2ndchancetoyotas Well-Known Member

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    Where did you buy the resistor? So in theory, if only the rears were LED, then the resistor would be .66 ohm?
     
  5. Nov 5, 2016 at 8:51 PM
    #5
    VE7OSR

    VE7OSR 'interfering with Natural Selection since 1990'

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    Depends on the LEDs you are getting, need to know their current draw. Resistors are available at electronic part suppliers; typically I give references to Digikey.com online catalogue items.
     
    2ndchancetoyotas likes this.
  6. Nov 5, 2016 at 10:46 PM
    #6
    jad3d

    jad3d [OP] Well-Known Member

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    I found a local store that had circuit supplies; you can definitely find what you need online. As for the resistor value, you would need to determine the combined draw of the incandescent and LED bulbs that will be on the circuit.

    Ditto. Online suppliers are usually my last go to if I can't find it locally.
     
  7. Jan 7, 2018 at 8:27 AM
    #7
    YOTA LOVER

    YOTA LOVER Stay Calm, and Fire For Effect

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    A slew of pricey stuff my wife hates me for.
    A little help please...

    First off, great thread! This is the route I want to go on my 2011. I plan on running sylvania leds 4157A for the front DRL/turn signal and the rear turn signal.

    I’ll do the math tomorrow when I’m at work, but I’m hoping the numbers are similar to what you have. The help I need is that I can’t see the four images you uploaded in the original post.

    1AD37B67-EC72-4123-9F2D-88A56C48EFAC.jpg
    FC27B841-F3BC-4760-B9C9-FB4732B9D253.jpg
     
  8. Jan 9, 2018 at 12:17 AM
    #8
    VE7OSR

    VE7OSR 'interfering with Natural Selection since 1990'

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    Armour: All-Pro Skid plates - IFS, transmission, and transfer case. Pelfreybilt rear standard plate bumper, Metal Tech Sliders w/ kickout and dimple die filler plates. Front Suspension: OME 885 + NitroCharger 9000 shocks + 1/2" spacers for a 3" lift. Superbumps replacing stock bumpstops. Camburg ball joint UCA SS braid brake lines Future: ADS Extended length, extended length UCA BJ to increase droop capability Rear Suspension: All-Pro Expedition rear leafs, Walker Evans 27" rear shocks, extended rear brake lines (Wheelers Offroad), U -bolt flip kit, rear Timbren bumpstops. Future: Hammer Hangers, Shock relocate, ADS 12" or 14" shock. Interior: Weatherteck floor liners - front, Wet Okoles- front, ScanGauge, LED interior & map lights. Power moonroof. Exterior: Raider Cobra canopy, retrofit headlight by Insight, LED bulbs all around, modified flasher unit for LEDs. Rear diff breather mod. Front diff vibe problem, driver's side needle bearing replaced with ECGS bushing. yet to install: HID Blazer Fog Retrofit, LED Flood & Spot, + switches, fuse panel. swaybar relocate blocks (build my own)
    Note that you need 3157CK for the front, and regular 3157 for the rear.
    With these bulbs, each draws 0.05A, 2 bulbs flashing = 0.05+0.05 = 0.1A

    Resistor in Flasher = .075V/0.1A = 0.75 Ohm
    example part
    https://www.digikey.com/product-det...nic-components/ERX-1SJR75/P0.75W-1BK-ND/35661
     

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