Any Wiring Gurus Here?

Discussion in 'Audio & Electronics' started by Z71Jack, Oct 12, 2017.

  1. Z71Jack

    Z71Jack Member

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    A few questions for you:

    1) When you wire auxillary fogs, light bars, etc have you typically connected them to the battery, fuse box, or tap them into the existing wiring? I see that most of the Rigid Industries lights are designed to be connected directly to the battery.

    2) Is there an access point in the firewall that you have used to run wiring from the engine compartment into the cabin? I found one on the driver-side firewall but it will probably require removing the instrument cluster---which I want to avoid. I'm hoping that there is another access point that won't require dismantling the dashboard.

    3) Can the existing OEM fog light wiring harness handle a slightly more powerful SAE replacement kit?
     
  2. dbbd1

    dbbd1 Full Access Member

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    1) I typically wire direct to the battery, with a properly-rated fuse and a relay. I run positive to the relay AND the load, then run a negative (ground) for the relay through the firewall to a switch that controls the relay. It may seem odd but here's the reasoning (a couple actually):
    - My 99 Ram worked off of a grounding system (as does my 07 Tacoma). The switches will switch the grounds on or off to control the item. This makes it simple if you want to tie your new circuit into an existing one (i.e. the fog light circuit)

    -But, the better reason is this: if you run a positive through the firewall and it is not fused (or fused properly), should it get nicked/abraded and short to ground, you will have an OOPS! moment. Followed my a cussword-fest as your battery melts down. If you only run a ground and it gets abraded, the worst thing that will happen is that your added circuit turns "on." Then you get out of the vehicle, pull the fuse or relay send continue on your merry way.

    And...
    You only have to run one wire through the firewall, the ground TO the relay. You can pick up a ground for the control switch from inside the cabin.


    2) I haven't checked yet but I usually sneak wires through around (or through) existing rubber grommets, etc.

    3) Maybe. How much more powerful? Just for grins and giggles I might use the existing harness, tie a relay in at the point where one of the bulbs would connect (tape/seal off the orther, of course) and then see #1 above.

    A word of caution that sometimes gets missed...
    How much more output will your new lights put out? Too much= too much heat= possibly melting your goofy, fragile, plastic (?!?!?) lenses and housings.
     
    Last edited: Oct 13, 2017
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  3. David Smith

    David Smith Full Access Member

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    x2 ^

    I agree with everything listed above. If you are concerned about high output lights on OEM wires, just use them as a signal wire and use a relay. That way your power is coming straight from the battery, and the OEM wires are just telling the relay when to open and close.
     
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  4. Z71Jack

    Z71Jack Member

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    Excellent points guys. Thank you.

    Driving Lights
    My goal is to add a set of Rigid Industries LED driving lights for off-road. They come with their own wiring harness that connects to the battery with a switch for inside the cabin. That is an excellent point about not mixing it with the OEM wires. The big problem that I am running into on the Tahoe is a good place to mount them.

    Fog Lights
    The OEM fogs seem a little weak. However, I don't see many aftermarket options out there that would be worth all of the hassle. I'll keep looking. Fogs to me are important when I have to drive on I-68 through parts of West Virginia. The fog there can be very thick.
     
  5. ScottyBoy

    ScottyBoy Full Access Member

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    I also agree with pretty much every thing mentioned above. With one exception though. I have sometimes run a positive wire from the cabin out to the engine compartment to trigger the relay. This us actually how I currently have my fog lights wired. I connected the positive to the ignition wire, and put a 5amp fuse on it. I do this for two reasons, one reason is so the lights that I have wired up can ONLY be on when the ignition switch is on. If I happen to forget to switch them off, they will still turn off whenever I shut the truck off. The second reason is because the switch I used has an LED indicator light on it, which needs a positive load on the switch in order for it to light up. The positive wire from the ignition works perfectly for this, as the only actual load on the wire is the LED on the switch and the relay coil being energized.
     
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  6. HiHoeSilver

    HiHoeSilver Away! Supporting Member

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    I'm with you here, @ScottyBoy. Especially the "truck is off, circuit is off" part. As long as you're fused correctly, if it shorts, the fuse will go, and because you are the one who ran the wire, you'll know where to look. If you know what you're doing, you will switch the hot side. Same in a house or building. If you leave a hot sitting at a fixture, and switch the neutral, you will stress components or burn bulbs prematurely. Ac or DC, those electrons are trying to go to ground. It is ALWAYS better to turn the flow on /off vs. giving /removing their path to ground.
     
  7. dbbd1

    dbbd1 Full Access Member

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    Huh? No, without a complete circuit there is no current flow. Period. Nothing is "looking" for a ground. The potential is there but that's what voltage is, is potential. You make it sound as though there are a sh!t-ton of electrons piling up at the switch just waiting for some action, like children jamming up at a school bus door.


    Although, I do sometimes used a switched hot from the engine bay fuse box for the relay positive. (Not sure if the Yukon actually has one as I haven't checked yet)


    And, did I mention that you only have one wire to run through the firewall, not two...
     
    Last edited: Oct 14, 2017 at 10:51 AM
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  8. dbbd1

    dbbd1 Full Access Member

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    And, if you really want yo get technical about it, electricity actually flows from negative to positive (in DC circuits).


    How come all of the car manufacturers these days have since switched to switching the grounds as a method of control?


    .
     
  9. HiHoeSilver

    HiHoeSilver Away! Supporting Member

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    They're not piling up, they're just sitting there. But they are certainly looking for somewhere to go. Hence, the potential you speak of. Give them a path, and they go there in a hurry. I know it's not what we're truly after here, but in an AC situation, this is problematic. Try switching the neutral on a light fixture vs switching the hot and let me know how long that bulb lasts. Or, better yet, remove the neutral from an outlet, plug your TV into it and see how that goes.

    Good points.
     
  10. dbbd1

    dbbd1 Full Access Member

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    Although we have wandered far afield...

    You're telling me that if I plug in a lamp, with a non-polarized plug, so that the switch is on the neutral leg, the bulb will not last as long? Why? Unless there is leakage (usually to a ground, if it's there at all), nothing will change. It is still an open circuit. Now, if you remove the bulb, stick your finger in the socket, that's another story...
     

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