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Discussion Starter · #1 ·
Hey everyone I’m looking to hook up my The Fuel Box auxiliary fuel tank. I need to tap into the fuse panel in the engine compartment with ignition power. What’s the best/cleanest way to install it? I have an add a fuse that can go right into an ignition fuse, but have to trim the fuse box so I don’t crimp the wire when I close the cover. Or can I remove the fuse box and add to a not used spot and how?
Thank you!
Install is on a 2020 3500 L5P High Country
 

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The problem I have had with getting power in the engine room fuse box is there is no elegant way to get your wire out of the fuse box. It doesn't look like a place you want to drill holes.

I have accessed power from the fuse panels on the left and right side of instrument panel inside. Generally left side has easy access to anytime power and right side is mostly switched power. The floor pan has several ~1" diameter rubber plugs that are easy to drill and run the wire thru.
 

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Hey everyone I’m looking to hook up my The Fuel Box auxiliary fuel tank. I need to tap into the fuse panel in the engine compartment with ignition power. What’s the best/cleanest way to install it? I have an add a fuse that can go right into an ignition fuse, but have to trim the fuse box so I don’t crimp the wire when I close the cover. Or can I remove the fuse box and add to a not used spot and how?
Thank you!
Install is on a 2020 3500 L5P High Country
Edit: Just saw that you have a 2020, duh. Hopefully the following is still applicable.

What gauge wire is it? If it's very small you can probably just pass it through the space between the box and the cover.

If you check out the relevant link in my signature you can see how I powered my auxiliary pump from an ignition-switched source. I didn't go into the main under-hood fuse box; instead, I went into the fuse panel on the driver-side of the dash. It's pretty easy to get the wires into the cab through the boot for the parking brake cable.
 

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Over the long haul, it's better to install an auxiliary fuse block that draws directly from the battery, especially when you start adding high draw accessories like lift pumps, fuel pumps, etc.

That's overkill for the kinds of pumps typically used with an auxiliary fuel tank. These things draw about 2A max.
 

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That's overkill for the kinds of pumps typically used with an auxiliary fuel tank. These things draw about 2A max.
I disagree. When you start adding a bunch of accessories like a lift pump, air compressor, and lighting which are all tapped into the fuse box, strange things start happening. I'm sure it depends on the age of the truck and the environment you drive in, but I've seen it first hand. All the electrical gremlins disappeared after installing the auxiliary fuse block.
 

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I disagree. When you start adding a bunch of accessories like a lift pump, air compressor, and lighting which are all tapped into the fuse box, strange things start happening. I'm sure it depends on the age of the truck and the environment you drive in, but I've seen it first hand. All the electrical gremlins disappeared after installing the auxiliary fuse block.
But he didn't ask about that; he asked about running an auxiliary fuel pump. That implies an incredibly small current for which a separate fuse panel is totally unnecessary. Furthermore, this is for a 2020 L5P and hence there's an in-tank lift pump, so the amperage draw of an aftermarket lift pump is not relevant to this discussion.
 

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Discussion Starter · #8 ·
As of right now I just have a add a circuit temporarily on the ignition fuse. It’s a low amp pump and only turns on when I’m on a half a tank. I just looking for a cleaner look. Dose anyone have a wire schematic maybe there’s a auxiliary fuse not in use.
1082471
 

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There are several empty fuse slots in the box. Did you test to see if one of those was powered with key-on? If so, you could add a fuse big enough to power your device and not have it piggybacked to the ignition fuse. I powered my homemade lift pump from an open terminal in the midbec under the dash by the brake pedal.
 

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In my experience there aren't any unused fuse slots that are wired up in the engine room fuse box. That box appears to be manufactured specifically for your VIN and equipment. Only way to get power here is to use the add-a-circuit as you've shown (but I'm stunned at how big your wire is). In any event, there is a schematic of the fuses and their use printed on the inside bottom of the cover for that box.

I HAVE found a few wired-up and not used fuse slots in the panels on either side of the instrument panel on my '20 GMC.
 

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I would run it just like you did using the piggy back fuse holder. I did this with my air compressor. I used a drumel and cut a small piece out of the side of the lid to the fuse panel.
 

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D22jaguar, did your installation work ok, without an error code on your remote? I installed the Firestone 2590 air compressor system on my '20 Denali and used a Fuse Tap in the same fuse slot you used, under the hood, in your picture (#40, Misc ignition fuse), but I get a ECN error on my remote. I was reluctantly thinking about moving my Fuse Tap to an "ignition on" fuse slot inside the cab, passenger side.
PS: I just joined the forum - lots of good information!
 

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ECN usually means remote can't communicate with ECU. try using the remote right beside the ECU to confirm
 
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ECN usually means remote can't communicate with ECU. try using the remote right beside the ECU to confirm
That worked, holding the remote close to the ECU, for a couple trials then error ECN came back. I fully charged the remote and tried again. Same issue, worked for a short period then back to ECN. All connections are good including good grounds connections. I may have a faulty ECU or remote. I'll reach out to Firestone or Autoplicity (distributor I purchased the unit from).
Thanks for your response!
 

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Discussion Starter · #17 ·
D22jaguar, did your installation work ok, without an error code on your remote? I installed the Firestone 2590 air compressor system on my '20 Denali and used a Fuse Tap in the same fuse slot you used, under the hood, in your picture (#40, Misc ignition fuse), but I get a ECN error on my remote. I was reluctantly thinking about moving my Fuse Tap to an "ignition on" fuse slot inside the cab, passenger side.
PS: I just joined the forum - lots of good information!
Everything works ok with my setup so far.
 
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