Trailer battery charge AWG wire size>

genestoy

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Does anyone with a 2021/2022/2023 Yukon or Tahoe know what AWG wire size goes from the underhood fuse block to the trailer hitch 7-pin plug for the trailer battery charge?
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jforb

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hard to tell looking at the wires, without taking stuff apart, but perhaps the metric equivalent of #12 or #14?

The fuse for Trailer Battery is #84 under the hood, it's a 30 amp fuse....

fuse engine guide.jpgfuse engine.jpg
 
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genestoy

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Yes, I knew the fuse was a 30 amp so I am "guessing" it should be a 10awg wire because 12awg is only good for 20 amps and 10awg is good for 30 amps. I hope GM is not installing a 30 amp fuse for anything smaller than 10awg?
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jforb

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Wire ampacity is not quite as strict as you might think....it depends on the application, and lots of other things.

One of the things I do in my spare time is mentor a high school robotics team. The competition we enter our robots in has a thick rulebook, and the specified minimum wire size for a 30 amp circuit in that application is #14 wire. And they don't catch on fire.

That said, you should use #10 wire in the trailer....
 
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genestoy

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A lot of the amperage capacity also depends on the length of the wire involved also which I am sure is much longer in a vehicle than a robot?
 

jforb

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Wire length affects voltage drop.

The operating temperature of the wire is related to how much current it carries. The insulation of the wire has to be able to withstand the temperature increase due to higher current. So the routing of the wire, and how many wires are packed in the same space, etc has more to do with it than length.

If you don't trust automotive engineers to size wires properly, then you probably should get a horse....
 
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genestoy

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So, if anybody knows the actual wire size that would be very helpful. I have searched online for wire harness diagrams etc trying to find the AWG size to no avail and I know GM customer service is clueless about these types of questions so please chime in if you know.
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wjburken

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For a 12V system I believe they should be 8AWG wires for a 30A load rated circuit. This is based on total voltage drop over the length of the wire.

This is based on my experience having designed truck equipment in the past and resources like the one linked below.

 

jforb

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The wiring diagram in the factory service manual should list the wire size. Let me know when you find the manual, please. I've been looking for a while, no luck.

It's definitely not #8.

You could pull the connector out of the truck, disassemble it, and measure the wire, then you'd know for sure. But unless you plan to replace it with a larger wire, which would be rather tricky to do safely, I really don't see how it makes any difference?
 

WalleyeMikeIII

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Curious why you want to know?

Not being a jerk here. But if you are planning on using the 12V line in the trailer connection, you already know the circuit has a 30A fuse in it, so anything you connect should have wire sized for 30A min.
 

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