Fuse Change for Horn Circuit.

I'm considering a set of PIAA horns. Specifically, a 4 tone horn set up, 330/400/500/600 Hz.

Each horn requires 2.7 A. Total current is nearly 11 A.

I'd like to use the existing wiring for a plug-n-play install. Yes, I'll have to add a couple of leads for the 4 horn system.

My question is about the fuse. Is is possible to replace the stock 10A fuse with a 15A fuse of the same type WITHOUT risking wire damage?

Conversely. Can the stock horn wiring handle a 15A fuse?

 

In my experience most stock wiring is barely adequate for stock fuses so I would say no.
You could however tie an acessory relay into the stock horn wire and run whatever size circuit you need (fused of couse) directly from the battery through the relay.

 

Yes. I know adding a circuit fed from the battery is a solution.

Although, I'd like to avoid add-ons to the battery. Prefer to use existing wiring for a tight, neat install.

Any thoughts or knowledge on the wire gage for the horn circuit? The wire gage will indicate the maximum amperage the wire can handle. I have dug thru the Service Manual for the '06 Tacoma in the Horn circuit section.......I have not found any mention of wire gage.

 

Short answer is no, the wiring is only rated for 10a

Use the existing wires as a trigger for a seperate relay for the new horns.

I've run aftermarket horns off factory wiring and I can tell you its not enough juice, you need a separate circuit.

 

Sometimes it's shown on the wiring digrams what gauge the wires are but I'd have to look.

 

Nuts........

I s'pose I could drop to a 3 tone set up to reduce the current draw to <9A.

Yes, I'm block headed......I just don't like the appearance of add-on DIY wiring. To me, that work always looks like a problem in waiting.

 

I agree I'm the same way because most of the time I see it poorly done but if I do it myself I know it's done correctly and the average person that looks under the hood wouldn't even know it was there if they didn't look closely.

 

From experience, horn wiring is no more than 24ga., if not 26ga.

 

Precisely.

24 ga? Thats light......going run some research.......

 

Do you have a access or regular cab? If so, you can use the rear power window fuses which are rated at 20 amps. Even if you have a double cab, put the window locks on and tap into that circuit so you don't use the horn and a window at the same time. Ashame Toyotas don't come with upfitter switches or a customer accessory fuse like the fords do, to give you aftermarket options though. For the price they charge you, a few extra feet of wire and fuse wouldn't be terribly more.

 

Interesting......

Stock horn circuit has a 10A fuse. If the wire is 24 AWG, it is only rated at 7A. Something ain't right. I don't believe Toyota would place a 10A fuse on a wire with a 7A limit. This would make the wire a fusible link.

22 AWG with a 10% voltage drop will handle 10A for 7 feet, based on a wire gauge calculator.........on the Web.

 

I am doubting you'd get a 10% drop over the course of a few feet, but yes the wiring that OEM provide are on the edge if not barely scraping by what they need to be, which is why I'd never add anything significant other than maybe a relay coil trigger via a fuse tap to the existing wiring.

 

@6 gearT444E Access Cab.

Right now, I'm thinking the stock wiring is good to run the 4 tone horn system with 11A draw on a 15A fuse. But I need to verify the wire size on the truck for the horn circuit.

I've got conflicting information at this point.

 

If you need any IEEE or NEC documents let me know and I can get you a real wire to amperage chart, not the one from grandpas garage.

 

Does automotive wire requirements fall into IEEE or NEC??

Yes, a correct wire/amperage chart for 12 Vdc applications would answer many questions.

 

I’d be interested in this.
I never found a good chart for when I was wiring a trailer.
The online “calculators” were all over the place. From 16 10 gauge.

 

there should be info for stranded wire vs solid, not necessarily automotive application.

 

Definitely interested in the stranded wire information.

After thinking about 120 Vac or 12 Vdc...... the voltage doesn't matter as much as the current. IIRC, an Amp is an Amp, independent of voltage.

 

voltage level will dictate insulation requirements, amperage will dictate wire gauge requirements.

 

Makes sense.