Horn (w/Relay) upgrade, where to tap into for constant 12V power

I normally tap my power off of the battery.

Alternatively, you could amp clamp the current horn wires and see if they carry enough current.

pwd847 said:

I normally tap my power off of the battery.

Alternatively, you could amp clamp the current horn wires and see if they carry enough current.

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About how much current is enough off the steering wheel switch?

Regarding tapping off the batt, easier said than done. G4’s battery is in the rear starboard side. Anyhow, I’d rather tap into the fuse box.

Sienna.Guy said:

About how much current is enough off the steering wheel switch?

Regarding tapping off the batt, easier said than done. G4’s battery is in the rear starboard side. Anyhow, I’d rather tap into the fuse box.

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Sienna.Guy said:

I'm looking into upgrading the stock horns. Is anyone familiar with where I can cleanly tap the relay into for the 12volt power?

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I’d investigate the fuse panel under the steering column. There is probably a 12v constant hot circuit there that you could piggyback with an add-a-fuse type device, then use the OEM horn positive wire for the trigger.

I added four Hella Supertones to my Tacoma many years ago. It sounded like a freight train and certainly command more attention on the road. Well worth the effort.

Sienna.Guy said:

Poking around the front fuse panel box, I found several unused hots to tap into. Challenge now is how to run it out without cutting.

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Would an add-a-fuse piggyback not work? Not sure the amp demand of the accessory horn, but if the draw is low enough, you should be fine. These can be had on Amazon for a $1-$2 a piece.


I’ve used these piggybacks to tap into unused circuits before. All you need to do is install the fuse for your accessory circuit and ensure the piggyback is oriented the correct direction - as explained here:

14:50 mark specifically

Doesn't the switch fire a horn relay? In my 06 chrysler, I used my horn relay to fire the aftermarket relay.

Stock switch outputting 2.6amps. I measured one horn, it’s 2.3ohms. Therefore in parallel, it should be approx 1.15 ohms, assuming the other is the same