Mystery electrical connector identification?

I was doing some preliminary wiring and testing to put some Hella supertone horns in my Tacoma today, and I found mystery connectors under my hood that aren't connected to anything, and I'm wondering what they might be for!

SR5 and up owners: Help me out here! See what these are connected to on your cars!

I have an SR Utility Package so basically if there's an option, I don't have it.

The most vexing/ important one, I think:

This sneaky bugger is front and center, under the hood latch at the bottom of the grille!

I'm going to go out on a limb here and make a wild guess that this is a secondary horn that higher trim models get. My reasoning here is every parts diagram I see says 2016 Tacos have 2 horns, and yet I mysteriously only have one. I'm also missing a relay in my fuse box, labeled "S HORN" ... there's both "HORN" and "S HORN" which makes me think there's an upgraded version out there.


I've made some progress with getting the Hella horns up and running with absolutely 0 wire chopping or splicing to the truck. Hella wants you to use their relay in the system, but the horns work just fine using the stock relay. The only potential problem is that the voltage drop from beeping the horns is like .5V, which means you're putting a much larger load on that stock relay. Hella horns are supposedly ~12A, vs my dinky little stock one listed at 4.5A, which makes the voltage drop more on the order of .1V when beeped.

If I could figure out what that damn "S HORN" relay is for, or how I could take advantage of it to potentially split the load, that would be awesome! I've learned over the years when it comes to electrics, that making any modifications modular and completely "unpluggable" is a godsend if you ever have an electrical gremlin to deal with.

 

And now for the other two less interesting (currently, at least) ones:


Behind the passenger's side headlight, down low. Gonna guess this is where the fog light harness gets plugged in?

And the other:

Driver's side, right next to the radiator. No effin' clue on this one. Some sort of sensor or something? It looks like a 4 prong terminal in there.

 

If no one else has an answer, I can go check mine tomorrow when it's light out.

 

That would be awesome, and much appreciated!

If you find where the fog lights are plugged in it'll also help me further down the road when I try to puzzle out a way to use the existing fog light circuits to integrate some aftermarket lights. (I've already successfully done that on a WRX, and it's really satisfying to have a big ass light bar that's 100% stock integrated- OE switch, OE relay, OE harness, no splicing to OE wires, just plug my custom made adapter pigtails in and light up the night by pressing the stock fog light switch!)

 

So I was able to take a few pics this morning. First things first was the fuse box and horns. I do have 2 horns, and a relay where yours is blank.
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The horns look like they're harnessed together.
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The one under the hood latch I traced over to the passenger side fog light.
(This is driver's side, but you can see what the connector should look like.)

And finally that strange one by the radiator. It's a sensor of some sort, but I have no idea what it actually is.
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Wow, I have absolutely no idea what the heck that sensor is! It looks like a little washing machine hahaha
Maybe that's not a sensor, could be the alarm beeper thingy?

I'm gonna take my grille off now because I know usually they don't make exclusive wiring harnesses, so there might just be an extra horn connector tucked in somewhere I totally missed!

That still leaves me stumped on this one though:

I guess that's not for the passenger's side fog light!

Anyways thanks for checking this stuff out dude, you rock!

 

Not a problem! I could have sworn there was nothing else on the passenger side other than the fog light harness. I'll try to look again and see if maybe I missed something or mixed up wires when I was tracing them. Either way, good luck with your project!

 

Hmm, so I just spent a while under the hood and I can't find an extra horn connector taped back, or even a wire that would give me a clue. Just one white wire going to my single horn and nothing else.

Funny, all these harnesses are so damn modular because they want to have one and only one P/N for a wiring harness, but an extra horn wire? Nope, remove it.

Also I just realized I've been being a bit of a dipshit and the "S" in "S Horn" isn't "Secondary" it's... "Security!" So it's not anything I could tap into for a doubled circuit.

That's not terrible news, though. If both your horns are on just the normal "Horn" circuit that means that there are 2 horns drawing ~4.5A each (it's marked on the back bracket of the horn) for a total of 9A. 9 amps vs the ~12 or so from the hellas isn't a massive increase. On top of that, as best I can tell those blue denso relays are all 20A relays, which means I've still got a generous margin of safety. It should be totally fine using the stock relay. Now to make a pretty harness to tie it in to a nice clean ground!

 

Wait a second though... @NM_Taco , can you confirm what amperage your horn circuit fuse is? It's written on the top of the box lid, it should be in the left most column and say "HORN" with "___ A" underneath.

I compared my fuse box to yours and it looks like we both have a 10A fuse there- running 9A of horn on a 10A fuse is cutting it awfully damn close, especially for an OE.

 

The "sensor" is the door lock/unlock beeper.

 

Hey @Nitori, I went out and checked a couple things for you. I unplugged that harness under the hood latch, and turned the fogs on. Nothing. Plugged it back in and the fogs turned on instantly. So that harness is for the fogs.

I just checked it and it is indeed a 10A fuse. You're right, that's cutting it super close, especially for OEM.

That makes so much sense now.

 

I can only assume that since the horns are the ONLY thing on that fuse, they figured it would be fine? I hate to have you making laps back out to your truck checking things but the amp draw is painted on the back. My single says 4.5A and you can read it without taking the horn off, just peeking through between the shroud. You'll need a flashlight though.

My phone flash lit it up nicely: (look right above the "EN" of "DENSO")


I cross referenced the part numbers and the 0E020 is the "low note" horn, yours will have the "high note" too. Who knows, maybe the high note is actually lower amperage!

Anyways, I think I've found the perfect solution regardless. Hella now has "SHARPtones" in addition to the traditional "SUPERtones" - they look very similar, but the sharp tones have a much lower amp draw at 3.5A per- lower than the stock horn AND are still 7 dB louder! Two 3.5A horns running on a 10A circuit is a reasonable margin of safety. Added bonus: the sharp tones are less of a shrill "euro-beep" that puts a lot of people off of them- they're 415/350Hz instead of the 500/300 of the originals.

Oh, and I got off on a tangent- thanks so much for tracking down the fog light harness, you rock!

 

I assume this is the fog harness ?
Did you locate the plug for the switch under the dash somewhere ?
Thanks.

 

That is indeed the fog harness.

The interesting thing about it is the OEM fogs are triggered via an ECU signal, that takes its signal from the turn signal / light stalk. SR trucks don't have the wiring needed on the stalk connector. So if you want to add it later, you need to add a dash button.

The one I still haven't figured out is this:

 

Yeah I saw that connector in there also, behind right headlight.