Any electrical gurus? Factory Aux question

[n118nw]

I was understanding that for 15A wires, you would want 14-16AWG wire, depending on the run... so if you wire up a 14Amp light bar on your roof.. the recommended wire is 14AWG since it's just over 4 feet.. but why in the world did Toyota use a 18AWG wire on the harness? I'm not crazy about going from a 18awg to 14awg when the weakpoint is going to end up being the factory harness... or are the recommendations overkill?

I'm going to be putting a max 14.4Amp bar on the roof rack.. about a 7' run since I'm snaking it up the passenger side instead of driver side, and i'm worried that anything smaller than 14awg is going to overheat the harness.

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[Sagebrush]

but why in the world did Toyota use a 18AWG wire on the harness?

You probably need to install a relay switch and have the lights powered via the battery and the relay coming off the 18 ga wires to connect to the switch.

 

[n118nw]

You probably need to install a relay switch and have the lights powered via the battery and the relay coming off the 18 ga wires to connect to the switch.

Daisy chain a relay? Interesting I didn't think about that.

 

[n118nw]

I'll be investing in a winch too but I'm not going to use a dash-mounted button for it; I'm completely okay with popping the hood a flipping a switch

 

[Sagebrush]

Something like this.

 

[n118nw]

Something like this.

So if I understand this correctly, ignore the Fusebox, SPST switch and indicator from the diagram as this is basically the factory AUX prewiring.. It's okay to wire the pigtail from any of the AUX's to pin 85 on a higher amperage circuit?

 

[Sagebrush]

So if I understand this correctly, ignore the Fusebox, SPST switch and indicator from the diagram as this is basically the factory AUX prewiring.. It's okay to wire the pigtail from any of the AUX's to pin 85 on a higher amperage circuit?

Yes.

 

[Sagebrush]

It's okay to

When I wired my behind-the-grill lightbar in my 2016, I used power from the high beam circuit for the switch, so there needed to be two things for the super-bright bar to turn on: the switch had to be activated, and my high beams had to be on. Thus, I could hit the high beam lever to turn the lightbar off.

I'm going to do the same with a set of Cali Raised ditch lights. At least that's Plan A. My 2024 is a month out.

 

[n118nw]

What gets me is that with everyone on the internet being an expert, for 15ish amps I should be using 14 awg for 6' runs.. but when I replaced the harness that came with my new light bar to a Deutsch DTP, the wire was 18 gauge.

Anyways I made a custom fuse/relay box and mounted it between the ECM and one of the few fuse boxes under the hood and it works like a charm and I have peace of mind now knowing I'm not using too small of a wire to power my lights. Thanks everyone for their input on daisy chaining relays.

 

[Sagebrush]

Anyways I made a custom fuse/relay box and

Exactly.

My new truck is sitting in boxes in Baja, but yesterday, I rewired the wiring harness of my newly purchased Cali ditch lights to turn on only when the brights are activated. Here's the diagram for the relay:

 

[n118nw]

That's pretty much how I did mine, x3 for each aux source. I've just never had factory aux lighting before and didn't know if you could daisy chain relays.

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