Horn Relay Retrofit for First-Gen 4Runners
 

Why this mod?
Because my horn sounds like Mickey Mouse with his balls caught in a mouse trap - LOL!
Why?
Because the current for the first gen pickup and first gen 4Runner runs from battery, to horn, TO CABIN, TO HORN BUTTON ON STEERING WHEEL, back to engine compartment, to ground point on inner fender; No different from the convoluted path of headlight and starter relay current. This causes lots of voltage drops along the wiring and horn button, and subjects horn button to full load current; worse if one upgrades to higher power horn.

This mod will fix that, and allow us to put higher power horn(s) if we want.* I think this Horn Relay Retrofit will apply to all First-Gen and earlier which do not have horn relay. (I don't know about the 1989 pickup.)
Yes, I will still inspect/fix the sliding pin/contact in the steering column.
https://cimg7.ibsrv.net/gimg/www.yot...a58aa08c40.png


Second gen 4Runner has horn relay to carry horn load current:
https://cimg8.ibsrv.net/gimg/www.yot...73fb47f2a9.png

HERE'S HOW I WIRED MINE:
Schematic explains most details.
IF you want to add an outrageously loud and powerful horn, I suggest you power pin 30 of relay with separate fused line from battery.
https://cimg1.ibsrv.net/gimg/www.yot...1591a86c68.png

OVERVIEW AND GENERAL WORK AREA IS UNDER RIGHT -SIDE FENDER, FRONT CORNER (BELOW):
https://cimg2.ibsrv.net/gimg/www.yot...2cb48d75bd.png

SNIP WIRES "A" AND "B" AT POINT WHERE IT WOULD BE EASY TO SPLICE / SOLDER.
https://cimg3.ibsrv.net/gimg/www.yot...79044fccab.jpg

SPLICE EXTENSION WIRES TO REACH RELAY IN ENGINE COMPARTMENT:
I put mine forward of the fuel injector resistor bank. Two feet of wire per extension worked well for me.
https://cimg4.ibsrv.net/gimg/www.yot...3fb863015a.jpg

I LINED TOP SURFACE OF WHEEL-WELL WITH THIN RUBBER SHEET TO PROTECT WIRES.
https://cimg6.ibsrv.net/gimg/www.yot...48b3ff2eff.jpg

I ALSO WRAPPED WIRE BUNDLE THROUGH THE GROMMET WITH SAME RUBBER SHEET FOR EXTRA PROTECTION.
https://cimg5.ibsrv.net/gimg/www.yot...d79098b387.jpg

I did not bother buying wires with stock colors so i just labeled new wires :)
https://cimg7.ibsrv.net/gimg/www.yot...b34ee05931.jpg

ALSO ON T4R HERE.

I like the piss-ant sound of my '87s horn. My family calls it the 'meeper'. Living in a largely rural area; I don't use it much.

:)
Need it in So Cal. Less wear than using the brakes - LOL!

So is this just the plan or have you done it yet?

Plan, but that's how wiring's gonna be.
Need to dig and see how to re-route wires from stock horn to fuse block. May have to expose area above wheel-well.

Even my 94 had a horn that sound like mouse balls..
went for an air horn.

I replaced my horn with some Denso horns from a Camry. My horn is pretty loud now. I also added a relay.
https://img.alicdn.com/i4/1613603684...0-item_pic.jpg

Nice! Adding more horns would definitely require a relay.
Ideally, may also be required on air horn, depending on how much current the solenoid valve draws.

Around the time you posted about this project I came across a nice nearly new looking pair of Lexus horns and scored them for nearly nothing. My question is . . . along with more horns requiring a relay would an increase in the size of the wiring to the horns be required?

Oh, and you guys know wayyy too much about mouse balls. :scared:

Same wire size as the ones going to stock horn or one size shud be good. The key is shortening the path and relieving the steering column contacts of the load current.
re balls,.LOL!

HORN RELAY RETROFIT COMPLETE! I UPDATED ORIGINAL POST ABOVE.

Hey RAD, this may be a silly question, but what relay did you use? Does it matter much what relay I get? Definitely plannign on fixing/upgrading my horn and your post is the impetus I needed. Thanks!

Most welcome. Standard 30-amp automotive Bosch-type relay is good and easily-available from parts store.

You might want to get a socket for the relay https://www.aliexpress.com/item/1Pcs...795113903.html (though most relay tabs are 1/4", so you can connect to it with a 1/4" female push crimp).

RAD4runner's drawing shows an SPDT (single-pole, double-throw) relay, but he only uses it as an SPST. So that's all you need.

+1^^^
Tnx for clarifying that detail, Scope.
All,
I updated schematic accordingly.

Electrons got lost. Direct Link to Picture is here. Will fix whn I get to laptop:
https://lh3.googleusercontent.com/Ni...=w1354-h669-no

First it's always a game trying to find that exact spot on the horn cover that finally honks the mickey mouse, balls in trap horn... by then it's too late and I've forgotten what i was trying to honk at... but, I feel like I won something just getting it to honk.

secondly... the horn is so cute, it's like whatever or whoever I'm honking at isn't scared, alarmed, intimidated in any way... they just look like " oh, isn't that cute," so I'll probably leave mine the way it is for posterity... it works for me.

I was thinking that same thing 😂 I wanna leave the old horn on a separate switch and label it "ignition kill" lol . But it would be good for when the person in front of you is asleep at the light. Mean horns like air horns scare them too much that by the time they are all done yelling at you the light is red again.

like others I want to add seporate duel horns. I can't see that wiring diagram though . Could you repost that Rad4runner?

Somehow google photos URLs and yotatech pages are not predictable anymore. I could still see schematic on original post above on my Mac Air running Chrome. If you could not see it, pls just go directly to the file itself here:

https://lh3.googleusercontent.com/Vg...Q=w873-h762-no