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Discussion Starter · #1 ·
I wanted to check on opinions and other options on a couple of wiring mods that I want to do on my 2014 Silverado LT CC. I am interested in adding both a tailgate brake light/turn signal bar and some lighting for under a bedcover. I would like to do this without having to splice into or cut any OEM wiring so I can remove if i need or want to. To power tailgate light strip I was going to get one of the T-adaptors (to go between factory harness and back of existing 7 pin plug on bumper) that would provide an additional 4 way flat plug for the light strip. I would rather not use the existing 4 way flat on bumper to power the strip. Then I would get constant power for the led lights under cover by spicing into the constant hot on the added t-adaptor (not original harness). Since it claims to leave full function of 7 way one of the wires must remain hot since I have tested and have a hot wire now without having to have key on. I am going to use 2 strips of lights mounted on underside of cover with a switch. The light that comes with the top is just not nearly enough. Don't think I need any additional fuses since everything is already fused. Any thoughts or concerns on this method? Any other suggestions to achieve same end result?
 

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I used a fog light harness to run 2 led light strips in my bed under the Leer fiberglass cap. All from Amazon for under $30 That way I had a switch, fuse and relay close to the intended use. I tucked wiring up under the cap edge and mounted switch accessible from opening the glass door on my shell. Did I have to, probably not, but I like over kill and if the lights stop working, I have easier access to everything. I tapped into the main constant 12v and sealed with rubber liquid tape. When the day comes to remove I can just snip it close and dap rubber liquid tape on bare wire and that's that. Not gonna hurt anything including trade in.
 

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GLS0628 said:
.... Don't think I need any additional fuses since everything is already fused....
The fuse rating is based on the circuit load and the sizing of the conductors. If you are adding to an existing circuit and your additions add significantly to the load, the fuse could blow or the conductor's jackets melt. Separate fused circuits for your additions would be the proper way to go. I suspect the fuse boxes provide for adding additional circuits with additional appropriately sized fuses.
 

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Discussion Starter · #4 ·
Thanks for the reply. My thought was that the 12V constant that I was going to tap into is fused for use through that 7 way. There is nothing on that line right now and I don't use the 7 way so the only thing that would be on it was the led lights for under the top and to line the inside of bed under cap rail. If I use all 16 ft of roll of led lights it says it uses 24 watts. I was going to use 2 rocker switches (each at least 5A) to control led lights in bed and top. The light bar is running off of 4 way flat that i know is already fused. Do you think that will put to much of a load on wire and connections without running another wire to fuse box? thanks.
 

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It's not about the ability of the circuit your tapping into as much as it is about isolating that "new" circuit to it's own circuit sized for the load. Ideally you want to use the battery to power your added fused relay. Let this new relay take on the work of this new circuit that is fused appropriately for the new load. I know it sounds like over kill for a small LED load or low wattage load, but it's the right thing to do. I used a fused relay kit and admittedly cheated and tapped the power wire you speak of till I obtain more wire and run to my distribution block at the battery I added for accessories. To save a bit on added circuits and switches, you can tap the wiring that is waiting to be connected to the factory bed light system an obviously not being used above the spare tire. It is located at #3 that #2 is plugged into at bottom right corner of block in diagram. It is blank right now. Then the bed lights will work with cargo light. I briefly considered it, but I have a block made for accessories and running up to that is easier for me and get the same result circuit wise. This affords me to add a switch at the rear. I plan to use a mercury/tilt switch on the shell glass. I have it, but too cold right now to mess with that.
 

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I have a terminal block in the front engine compartment that feeds off the power terminal on the front of the fuse block. I can hook any circuit into that terminal block to a separate fused connection. From one of those connections, I ran a 12v+ line from the engine compartment to the back of the bed. I have some relayed LED aux reverse lights and my under switched rail LED bed lights both hooked up to it. I run both off a 10amp fuse in the terminal block. I also have LED underhood lights and another accessory hooked to separate circuits on the terminal block under the hood.
 

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You guys are just tapping into the 12V accessory power on the 7-pin connector? hmm, maybe i'll go that route.

On my 2010, I tapped into my interior dome light wire in the driver's A pillar to energize a relay, thus energizing my bed lights. I loved it. All I had to do was hit my unlock key FOB and the bed lights would come on. Everything was fused and protected as the relay was located by the fuse distribution block and ran off the fused power lug. Additionally, I ran 12v back to a 3 position switch in the bed where I could either 1. have lights come on via interior dome light. 2. turn on at switch. 3. disable (off). I'm trying to figure out how to do the same thing in my 2014 since it has the cargo lighting feature.
One thing I had to do with the relay was install a small capacitor and diode on the coil of the relay since the dome lights dim when they turn off. Without that, the relay would buzz every time it deenergized. That worked perfect for 6 years.
 
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