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LED foglights as DRLs, what 12v wire to tap?

Discussion in 'Gen 3 Prius Accessories and Modifications' started by xliderider, Sep 3, 2012.

  1. xliderider

    xliderider Senior Member

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    I'm getting a pair of these amber LED H11 bulbs for the OEM foglights to be used as DRLs:

    Yellow / Amber LED Fog Light Bulbs 3 Watts Headlight H11 | eBay

    I know they probably wont be as bright as a 55w halogen H11 bulb, but that is a good thing IMO because the standard reflector has zero cutoff and splashes light everywhere creating a lot of glare at night. The other advantage to these LEDs are that they are only 3w each, so they will draw a lot less power and create a lot less heat when used as DRLs.

    Currently, the OEM foglights are tapped into the brown wire under the dash per the standard intsructions, which supply power to the foglight relay when the parking/low beam lights are on. What wire can I tap into for a 12v source when the Prius is in Ready Mode?

    Thanks.
     
  2. sfv41901

    sfv41901 Masta S

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    Under the dash I'm not so sure, but under the hood u can use the grn wire going to the windshield wiper motor......that's hot when in ready.
     
  3. xliderider

    xliderider Senior Member

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    Thanks for that, but yeah, I was hoping to tap a wire under the dash since I went through the trouble of threading that harness through the firewall lol.

    Guess I'll peruse some wiring diagrams and see what's available.
     
  4. ucsmfu

    ucsmfu Senior Member

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    will that work with Bino's L shape led DRL's as well ?

    thanks
     
  5. sfv41901

    sfv41901 Masta S

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    Time to get the volt meter out & start stabbing at the terminals to find ur "hot when ready". If it was a hot all the time u needed I could show u where that is.
     
  6. ucsmfu

    ucsmfu Senior Member

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    Hi Sean, will any volt meter do ?

    Where and how do I begin testing ?

    thanks !
     
  7. KK6PD

    KK6PD _ . _ . / _ _ . _

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    You have to be sure that the wire you tap into has a fuse connected with it that will handle the load it was intended for, as well as the additional load you plan to add, failure to figure this out at minimum will cost a fuse. Radio Shack sells fine inexpensive voltmeters. You will have to read directions on use since you seem unfamiliar with VOM operation. It's a simple device, red and black, positive and negative! Select the proper range, take a reading!
     
  8. xliderider

    xliderider Senior Member

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    I just need enough current for the relay. I'm familiar with using voltmeters but I was hoping someone would know which wire was hot at Ready to save time. ;)

    ucsmfu, you need to have a volmeter with some needle tip probes so you can get the readings at the base of the connectors in the wiring harness. Still, it will probably be difficult with the tight spaces under the dash.
     
  9. xliderider

    xliderider Senior Member

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    Update. Finally installed the 3 watt amber LED H11 bulbs I got. I must say I'm disappointed, but they probably would've been much better if they were 7 watt LEDs.

    Here are some pics, all pics taken with only the parking lights and the LED bulbs on (in the foglights):

    Shaded in the garage:
    [​IMG]

    Outside in full sun coming in at a side angle:
    [​IMG]

    Outside in full sun, coming in head on (note glare bouncing off the front badge):
    [​IMG]

    This full on sun shot shows the LEDs as practically useless. I haven't re-aimed the foglights to shine higher up though. They are still aimed quite a bit downward from the original aiming when I had 55w halogen bulbs installed. Since these LEDs are quite a bit dimmer, I figure I can really crank them up to "eye level", and maybe it will make a difference.
     
  10. xliderider

    xliderider Senior Member

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    I'm going to use a mini ATM fuse tap to draw power for the relay for the fogs from the fuse box. Was originally going to tap into the one in the engine compartment, but since the red wire is already near the driver's side kick panel, it might be easier to tap into a fuse in the lower dash.

    Any ideas about which fuse to tap for power when in Ready mode only would be appreciated. ;)