That diagram on parts.toyota shows the locations and names of the horns. They call the one between passenger fender and airbox the “anti-theft alarm siren”. Here’s what mine look like.

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Well whadayaknow, I do have that horn by the airbox. The one I’ve got in the front looks like that one.
I couldn’t set off the alarm by arming and opening the door, maybe I didn’t wait long enough for it to set. I did get at least the side horn to go off by using the panic button. It was much louder than usual so I would think both were blaring. I really don’t want to test it any more in my quiet neighborhood right now.

I can confirm there are two horns in the front of my 2012, but they may have changed to that after 2010.

I remember the factory horn on my '10 TE, single horn and sounded like a small Honda Civic horn, it was a must replace, it was embarrassing.

I i have been tearing through the fuse box and relays. I have disconnected the one working horn to listen for the relay. I can hear it and if i pull the 10amp fuse for the horn it does stop the relay. the weird part is I CAN NOT Find the relay! i pulled every relay in the fuse box and pushed the horn pad and i keep hearing it. how ever after the last post i wonder if this 4runner was only equipped with this little horn by itself? time for another upgrade!!

Hmmm

The horn fuse and relay (as well as three other fuse/relays) are located in the "integrated relay" module also known as Unit K and stamped “K”in the engine fuse box.
If you press the horn button and it blows, it’s all working OK.

If you want a different or louder sound you’ll need an after market horn or multiple horns. Search the forum for other early 5th Gen horn mods.

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Yeah after all the searching, cross referencing, wire diagrams and a call to the parts dept. my 4runner just has one pathetic little horn. So my next question ElectroBoy, the pic you posted earlier, is that a stock pic behind the grill or your 4runner? if so can you tell me if both of those horn use one plug? or do they each have their own? i guess i can pull the cover off the wife's 2019 and look. but yes ill be getting a newer horn soon. this thing is pitiful!

Thanks everyone for their input, advice and help. i guess the bright side is i have a newer clock spring that I didn't need! LOL

I’m glad you started this thread. I got off my ass and pulled relays/fuses to see what does what.
Upgrading my weak horn is a project I’ve been meaning to do for 10 years. Might just need to get it finally done.

OP, did you see this thread?
New Fiamm Horn Install

Those pics above are the horns from my 2018 ORP. Each has its own connector. If you look at the wiring diagram PDF I posted above you’ll see that on at least one trim of the 2010 MY there were two horns installed, driven from one relay. So the horn relay contacts should be able to handle a two-horn retrofit.

I’ve used Fiamm horns on another truck in the past, as @1000MPH linked, this is a good post for install instructions. There are several models available so you should research which ones to use. IIRC, they come with two electrical connectors for +12 and GND. The mounting bolt may not be connected to the GND circuit so you’ll have to test this and maybe make a connection to GND with a separate wire.

Just a note.
Adding a horn is easily doable and should not cause any issues.
I had a 2013 FJC, it came with 1 horn, yep....that's right a 2013 FJC with one horn.
I looked up the part number of the OEM horn and ordered a mate for it. Made a split jumper and eureaka.... a much better horn tone!

OEM 2nd Horn Wire

i think that is my plan

I'll Definitely will check it out

I just replaced mine with a Fiamm freeway blaster low tone. Pretty much a direct swap.
I A/B’d them and the new one sounds like a normal horn. No more 50cc scooter horn sound.
Here’s my factory single horn setup.

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