Installing Aftermarket Horns

[ARCHINSTL]

While this may seem like child's play to many, to others (like moi) electricity and its accompanying wiring is baffling.
So, when I installed two new horns to replace Goldie's mewing emanation, I worked up the diagram.

I used one each of Blazer (Fabrizio en Italia) brand high and low tone bugle type horns. I think they are about 112 +/- dB, and each cost $15 at AutoZone; I did not pop for the 132 dB version at $20 each. Two of the same tone would be equally good - my ears cannot detect much of a difference between the two sounds...

I mounted one in the OE position and the other in a similar position in the opposite fender. I used 14 ga. wires and regular male and/or female connectors. It was female spades into the OE "connector" for the OE horn.

I used a 40-amp relay and a 30-amp inline fuse holder. When I called Pilot, the importer of the Blazer horns, no one knew what the amp draw would be...but guessed that 10 amps would more than cover one. I doubt I'll ever add a third horn, but I'll be covered - just substitute a 30-amp fuse.

Incidentally, I checked the voltage at the OE horn - it was something in the 4+ volt range as I recall; going direct to the battery, the horns are getting 12+ volts - so they ARE louder using this method.
I also tried hooking up both horns to the OE wiring to see what would happen: Nothing happened; neither sounded, so I guess it was too much of a draw (at least I did not fry a fuse or wiring - lucky, but don't try it - just in case...).

Anyway, to the ohm-innocent, here it is!
Tom M.

[Typrus]

Ahh, the wonders of insufficient wiring. Go Japanese noodle-wires! + time! lol.
I put in a high-tone Blazer (the bugel-looking kind, not the flat pan one) in harmony with the OE one. It sounded pretty good. Probably could've used more currant (and better in-wheel contacts)

I always thought about doing the red ones. But figured against it later. lol.

[takza]

I have a couple of Eyetalian air horns installed...new ones from Advance I think. I just used the power wire from the original horn. Very loud...seems to me. Not sure why you would see 4 volts.

I did use a relay though.

[terkill]

I had picked up some Saab 900 OE "Hella" horns at a junkyard that tore a hole in the sound barrier but i had some trouble getting to the stock horn in the fender, as a piece of rust was blocking the removal of the plastic fender shield. So I sold them to a friend. How did you get to it? my arms are like shoelaces and I wasn't able to even get to it

[ARCHINSTL]

I forgot - the horns I used were the bugle type, too.
I figured they would be louder than the disc type - no empirical knowledge, they just "looked" louder.

Dunno exactly where the horn is in the OZ-directed Wagons, but here in N. Murrica it is mounted on the "radiator bulkhead," just above the brace from the "bulkhead" to the bumper cover and just below the headlamp; it is quite visible from underneath. It is accessible, but kinda awkward to manipulate the wires and brackets.

I used a stainless-steel bracket from a Blackburn bicycle rack mount to lower the horn from its original position to both make room for the relay - and to give room for my mitts to move.
Incidentally, I also used a piece of a mountain bike tire tube to enclose the relay - I figured it needed protection from the elements. I mounted it close to the OE connector shown to eliminate the excessive wires, were it mounted it next to the battery.
Tom M.

[tercelboy]

i rednecked a couple extra hornes on mine in the stock wiring only they wouldnt stop going off scared the shit out a me

[ARCHINSTL]

Follow the diagram; it works.
Tom M.

[gmeddy]

my horn has just started dieing on me. I might jump onto ebay and see whats available. i got a pretty good one for my Toyota Surf (LN61) about a year ago, it is sort of spiral with big bugal opening at the end. sounds pretty good.
That one i just wired up to the OM wires. maybe it would be louder if i ran new wires for it like the diagram.
i will do the wiring propperly for my tercel, as i love it so much more than my surf, just because the surf is a 2 door and chews more juice (diesel) and i cant work on that engine, luckily dont need to and will sell it before i ever do i hope.

[GotToyota?]

Question about this. I am attempting to install aftermarket horns and found an issue with just wiring it up into the factory plug.

There are two wires going to the factory horn plug, one is green/red and couldn't make out the color of the other. Which wire goes to each part of the relay? 85 and 86, or does it matter?

Also the diagram for my horns says I should use a 10amp fuse. Can I use 20 or would it be better to use what they suggest?

[dlb]

GT, i'm not sure about the wire colours but take a look at the wiring pages in the back of the FSM. it should tell you which wire is which.

regarding fuses, the only problem of going with a smaller fuse is that it will blow too easily if it's not big enough—no big deal. but the danger of using a fuse that's too big is that it may no longer be the weak point in the circuit. this means the circuit might blow somewhere else and be difficult to find, and could start a fire. very bad!

[c_j]

There are two wires going to the factory horn plug, one is green/red and couldn't make out the color of the other. Which wire goes to each part of the relay? 85 and 86, or does it matter?

It does not matter (unless you bought diode-protected relays - probably not though).

Also the diagram for my horns says I should use a 10amp fuse. Can I use 20 or would it be better to use what they suggest?

dlb is right. For reference, here are some safe maximum fuse sizes for the wire you are using:

Code: Select all

#18 AWG - 10 AMP
#16 AWG - 15 AMP
#14 AWG - 20 AMP
#12 AWG - 25 AMP

(AWG = American Wire Gauge)

These fuse sizes are based on:

• a wire insulation temp rating of 105 deg C
• maximum of 3 wires running together in a bundle
• wires are running though engine space
• we are doing this wiring in a boat*

*no, the T4 is not a boat, but boaters have good rules and guidelines to go by