How I Fixed the Horn on Toyota Mark II

Recently I asked, how to make a horn work on the car.

But that didn't really help much, so I had to figure it out myself.

So, what's the main feature of the horn on this car: constant 12V is supplied to the horn, basically from the battery. So if there are no 12V, you can easily attach a new beautiful wire directly to 12V. But the minus is interrupted. Interrupted by buttons on the steering wheel. This was done so that there would be less sparking and thus less oxidation.

In short, there are no relays in the circuit, the wire from the horn goes directly to the buttons.

I started checking the chain. The first place where problems can occur is where the steering wheel meets the steering column. There is a spring-loaded contact, and on the steering wheel there is a round plate. That's basically how the contact is transmitted to the rotating steering wheel. If the car stands for a long time, everything oxidizes there. You need to remove the steering wheel and clean it. And fix the plate if it has bent. But when I was assembling it, I did that. So I didn't remove the steering wheel. I was confident about that contact. Therefore, I decided to look at the buttons. It turned out I was right.

Here is a copper plate

You can see oxidation marks on it.

And here's the back of the button

It's also clearly not in its proper condition there)

Damn, cleaned everything thoroughly with sandpaper

And everything worked perfectly.

Heh. That's all. The car keeps surprising me every time. In each malfunction, the solution turns out to be extremely simple…