Fiamm Highway Blaster Horns From Napa Auto Parts
4/8/2003

The stock horn on the Toyota 2nd gen 4Runners and trucks of the same year just plain out sucks!
It's one horn, and has the little "beep beep" sound to it.

In my quest for louder horns, I had bought a twin pack of air horns.
I could not find any room under my hood to mount the compressor, so back they went to the store.

I then found out that Napa Auto Parts carried some very loud horns called Highway or Freeway Blasters.
You buy them separate, and they each have a slightly different tone to them.

Now the fun begins.
Toyota uses a weird type of power and ground setup on my year of vehicle.
I cut the two wires going to the stock horn.
I then bolted on one horn in the stock location on the passenger side and hooked up the power wire first.
Off it went and about blew me on my keester.
I was not prepared for the loud sound it made, or for it to go off.

What was happening is that the positive wire for the horn is always hot.
The stock horn mounts in a way to isolate the frame of the horn from the frame of your rig to not ground it.
When you push your horn button, you are completing the ground circuit, and not the power circuit.

So with these new horns bolted up, they were always grounded.
What I had to do was get a 30 amp relay much like the ones I use for all of my off road lamps.
The relay has the positive and negative wire from the stock horns harness going into it.
It wires pretty much the same as doing a set of lights.
In the above diagram where they have the positive wire from the battery and ground wire going to the relay, I substituted the two wires from the horn harness.
I also put an inline 30 amp fuse on the positive side of the wire going to the relay.

Then there are two wires coming out of the relay that will be for the positive and negative sides of the new horns.
They now receive their power when you push the horn button.
Having the relay also assures you of having more voltage available for the new horns.

The drivers side horn has a red positive wire going from it right to the relay, and the passenger side horn has a red positive wire also going to the relay.
The relay allows you to have two positive wires feeding into it.

Here are a few pictures of the horns.
They are kind of hard to see as they are tucked down inside the grille pretty good.

The driver side horn had a short piece of wire from the horn that grounds to a point under the hood not shown in this picture.
I also had to make a custom bracket to hold the horn in place.

The passenger side horn only has a positive wire going to it from the relay since the horn is always grounded to the frame where it bolts up.

Here is a 447 kb video of my horns.
It is an old one, and I will update it sometime.

I hope this makes sense.
I am not an electrical engineer, but I know how to wire up this type of stuff and off road lights.
Just spitting out the technical jargon is a little bit harder.

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