DIY underhood light - 2011+

Discussion in 'DIY Tech Guides' started by Entrenched, Jul 6, 2011.

  1. Entrenched

    Entrenched forum member

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    I bought my Led panel from here:

    V-LEDS HID WHITE 48 M-SMT PCB 194 158 168 57 BA9s 3175 DE3175

    You don't need a base and if you "like" them on Facebook you can get a discount code.

    [​IMG] 12V 30A RELAY WITH 5 WIRE SOCKET HARNESS SPDT | eBay

    This a universal 5 prong relay with harness. Amperage is not important as the light only draws 360mA. I got mine from Pepboys (I had to go behind the counter and find it myself because they were lost). Sorry no part numbers but you can find these locally, but they will be a little more expensive.

    First locate the hood switch on the passenger side fender. This part of the security system and I assume all cars have this:

    [​IMG]

    This switch has two wires: one in black the other is blue w/ a pink stripe. We will use the blue w/pink stripe wire to trigger our relay. The trigger wire is a reverse ground trigger and should be wired like this:

    [​IMG]

    and mounted here for easy access:

    [​IMG]

    Run the wires for the light under the hood blanket and mount your light. I used Gorilla glue and mounted it directly to the hood liner.

    [​IMG]

    [​IMG]

    Enjoy!

    [​IMG]
     
  2. VTXFrank

    VTXFrank Obama SUCKS!

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    I keep a couple of those relays around for little projects. You can often find them at Radio Shack or as part of some fog lights or switches at autoparts stores, if not the relay itself.

    That's a very good idea you had there. I will copy it soon!
     
  3. Bmr4life

    Bmr4life 2005 GT

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    Thanks for posting this.
     
  4. JeremyH

    JeremyH 3V Fuel Guru

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    If you mount the led higher up on the hood theres an angled spot up by the latch that lets you mount the leds and point them straight down in the engine bay to spread more light into the nooks and cranies. My setup has 3 leds and i have them angled slightly different to shed light all over. Lets you see all the way down between the engine and radiator and on the side of the motor as well.

    http://www.s197forum.com/forum/showpost.php?p=779660&postcount=18
     
    Last edited: Jul 7, 2011
  5. TexasKyle

    TexasKyle D.I.L.L.I.G.A.F

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    You really don't need a relay either. You can just run the lights off the switch. I have three sets of LED's mounted as Lightblade described and run them in series together and back to the hood switch.

    Not trying to pee in your Wheaties, just saying it can be simplified.
     
  6. Entrenched

    Entrenched forum member

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    Using my method requires a relay as the switch is a reverse ground trigger. In other words, the switch is grounded when the hood is closed. We want the light on when the hood is open (and so is the circuit) thus requiring a relay.

    If you know of an easier way to accomplish this let me know.
     
  7. Bmr4life

    Bmr4life 2005 GT

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    Hmmm. So there are there two switches that know the hood is open or just one? Also, I'm not sure all mustang have the switch the OP has. Mine probably does, but I also have the security system so my alarm goes off if the hood is opened.
     
  8. JeremyH

    JeremyH 3V Fuel Guru

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    Yeah your application does require a relay i didnt use one as I used an additional pressure switch.
     
  9. wystewart

    wystewart Junior Member

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    should really put a diode across the relay coil (85, 86) to clamp the negative voltage generated when the relay turns off. The negative voltage could kill the PCM.
     

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