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Bed Light / Reverse Lights Write - (My Half-A$$ed attempt @ doing a write up)

Discussion in 'Lighting' started by lookylookitzadam, Jun 19, 2010.

  1. Jun 19, 2010 at 9:55 PM

    lookylookitzadam [OP] Retrofit Club!

    Jul 16, 2009
    First Name:
    San Diego
    07 DC OffRoad
    1. I am not responsible for anything that happens to your truck or you. If you don't understand electronics, then this isnt for you. By reading this thread you assume all liability (my lawyer made me do this)

    2. This write up sucks, I know...but I will help you if you have questions. I have been doing this stuff since I was really young, so I take a lot of stuff for granted and skip the small steps, ask if you have questions.

    3. ENJOY!

    Background of Why I did this mod:
    So I was bored this morning while my girlfriend was at work so I decided to get some stuff done on the truck. Since I had just stumbled across the most awesome electronics store and bought a ton of components (relays, diodes, etc), I decided that I needed to do something with these.

    I always wanted brighter reverse lights and also some bed lights/off road tail lighting and wanted to integrate them together.

    What this mod Does:
    This mod will provide you with bed lights that can be turned on with an in-dash (or wherever yo u want to mount it) switch or will automatically turn on when shifted into reverse.

    The Mod:

    I started out by mounting these lights to the bed rails. I utilized some L brackets connected to the bed rails with washers and bolts and screws, this is pretty self explanatory and will change depending on what lights/brackets you choose.


    Closer shot of the passenger side light:

    The lights are connected in series, so the power and ground come from the drivers side light to the passenger side light, this doesnt really matter, but this is how I did it.

    Wiring layout and routing is pretty much up to you.

    I ran 12v directly from the battery with a fused link to the lights.

    I tapped the towing harness for the reverse signal as seen below. This can be done multiple ways (reverse lights, inside the cabin, etc). Just depends where you want to pull your reverse signal from. This signal will power the relay causing it to switch pins and illuminate the lights when you shift into reverse.


    The ground wires from the lights and the reverse signal wire were run through the grommet on the drivers side. It comes up right below the front of the drivers seat.


    Then its time to wire the relay. I wired it as shown in this drawing below. Sorry that it sucks, it was drawn on a laptop. LOL


    Whats going on with this relay stuff?

    Whats happening here is this:

    SPDT (Single Pole - Double Throw) relays sit with 87a normally closed. This means that pins 30 and 87a are connected in the relays resting state. When a relay receives power across its coil (85-85) it will switch from 87a to 87. This is why when the reverse signal is detected, the relay flips to 87, and turns on the lights, completely bypassing the switch.

    I installed the relay here:

    And ran the wires up to the switch:

    Thats pretty much it, i just installed the switch and tested them out.

    result pictures (way brighter in person, keep in mind these are driving lights:eek:)



    Thanks for reading, let me know if you have some questions.
  2. Sep 20, 2011 at 6:07 AM

    TacoDaTugBoat Well-Known Member

    Mar 24, 2009
    Goshen, Ct
    13 DCLB TRD Sport
    Very Interesting. Sub for later use.

    Can you be more specific about what type of relay? I don't know much about them or if there are types. Where would I get one? What gauge wire is needed for a typical pair of lights? What kind of switch would I need? Is the coil supposed to be (85-86)?

    Thank you
  3. Sep 20, 2011 at 8:21 AM

    iroc409 Well-Known Member

    Jul 8, 2009
    A red one
    Standard Bosch style relay. You can get them for a few bucks at any auto parts store, or online places like Del City. The pins for these style are standardized. Yes, the coil is on 85 & 86, and 30 & 87 are your load.

    I would put your switch on 85 & 86 though (depending on where you mount it I guess). Putting the switch on 30/87 makes the full light load run through the switch. Significantly less current on the relay coil side (in the mA).

    Mine aren't switched, and are under the bed/bumper. The relays connect to the factory reverse bulbs. I have no reason to switch them, so I don't. It greatly simplified wiring for me.

    ETA: Nevermind, I see what you did. You used the switch to turn them on-demand via negative switching. I've never needed them unless I'm reversing, and don't like switching full-current. It's a good idea, though.

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