I have searched Google and on this site. I need some help. I have a 2010 TE. Only one of the two tones on my horn work when I press the horn but both work when I hit the panic button. I checked the fuse and replaced the Clock Spring (with an ebay one). I've read to check the ground on the horn pad, it is securely connected. Am I missing something? I thought about popping the horn pad out of the wifes 2019 to test and see if it's that but I doubt it.

Does seem strange since both horns are usually wired together off the same relay. (The relay is energized by the steering wheel horn pad). My guess would be there is something intermittent in the horn wiring, possibly the ground connection.

The alarm has its own separate “security” horn, I believe it’s hidden in back on the passenger side. So you actually have 3 horns.
In the engine fuse box there should be an S-Horn relay and Security fuse.

Looking at an old confusing wiring diagram, the wiring is not absolutely clear, but:
For the low tone horn there should be a HORN relay (maybe called H-LP LO) and a HORN fuse.
There may also be a separate high tone relay (H-LP HI) and an H-LP HI fuse. Is it the high tone that doesn’t work? Maybe that’s your culprit.

Otherwise troubleshoot the horns themselves. Pull off the wire connector of each and look for corrosion. Energize each horn with 12V, does each one work? Leaving the connectors off hit the horn button. Listen for the clicking of the horn relay(s).

So I have found two horns, one right behind the grill and the other is behind the air box. The one behind the grill is the one that works with the horn pad. I thought the security relay was just another relay for the same two tones, just a different circuit. The one behind the air box does sound off but only when I hit the panic button. I will try disconnecting both and hitting the horn pad to listen for the relay. Ill also look for the two fuses you recommended.

I did notice both are not on the same wire harness. I have thought about just jumping the two together from the known good lead. The Ground for both horns is just the screw that mounts it to the aprons. They were clean and the horns are functional. It's just hard to be taken seriously when i honk my horn and is sounds like my dogs squeaky toys

Is this a new-to-you 4Runner from a previous owner, and you’ve just discovered it only has one horn behind the grille?
You should have two behind the grille.

Don’t jumper anything to the security alarm horn. It’s a totally different system.

Look for the mounting location of your second horn. There should be a horn and harness for it. If it’s missing you’d be better off to buy a new horn of the correct tone and install that.

Only one horn on my 2010TE.

Really? I was looking at this page from the 2010 manual that was posted on the forum. There is a note (*1) on the power wire from the Lo horn A21 to the Hi horn A20 that says "w/ Smart Key System". That's the mystery note, I wonder if it means there is a second horn only on 4Runners equipped with smart keys.

@1000MPH , is your horn horn dual tone?

Attached Images

Theft Deterrent (2010 4Runner) .pdf (45.5 KB, 45 views)

I don’t even know what you guys mean. I haven’t seen a dual tone horn since a 1972 Jag. Are you saying the alarm has another horns? The alarm I’ve never set off? I guess I’ll check that tomorrow. Do I need to set the alarm with the window down to test?

If it’s like the OEM alarm system in my 18 ORP, sit in the drivers seat, set the alarm. (I use my key fob to lock the doors/set alarm). Manually unlock your door with the knob, open door, plug ears. Then reset/stop the alarm by hitting the unlock button on the fob. If you have an after market alarm this procedure may be different.

I guess the idea of a separate security horn is so a thief can’t just open the hood and easily yank the wires off the horns in the grille. The alarm horn is buried deeper and takes more work to get to.

I just had the cover off my 17 SR5 (adjusted headlights) and happened to notice two horns mounted side by side.
No idea what it/they sound like as I have never honked it/them.

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If you ever feel inclined take off your air box, the second tone is right behind it mounted to the Apron.

The Security Horn/Relay I thought was just a separate circuit for the Panic/Alarm? The only other horn i know of in the car it a the Beep you hear when locking and unlocking the vehicle.

Ill have to double check under the hood again. I only found a Security Horn relay and a horn fuse.

At some point they went to two horns in front. Soon after the 5th Gen intro. If you look back there were a few threads about replacing the horn(s) since they were so pathetic.
Looks like they changed them more than once.
HORN. 2010 Toyota 4Runner | Toyota

After looking at the fuse box diagram there are H-LP LH & RH HI/LO, these seem to be the Hi and Low beams for the headlights but I do see one labeled H-LP HI ill have a look at that one. also going to track down a similar diagram for the relays in the car