horn button and signal wiring

[robbkramer]

Hi all; I have new parts for my signal switch and horn button, but I'm at a loss how the horn contact point actually works. If you see the pics, you can tell I didn't have much to go on as the condition of the components was pretty bad (the contact spring unit was lying in the grime at the base of the column cup).

Where does the contact spring for the horn button fit, inside the column on the base of the new switch assembly?

original-signal.jpg

new-swtich.jpg

spring-contact.jpg

[Art]

That horn contact acts similar to a brush on an electric motor, the metal bullet looking button end rides spring-loaded against the metal ring on the bottom of the steering wheel. Basically just put it spring end first into the cylindrical hole of the new turn signal switch that is almost opposite the turn signal switch lever pivot point. It almost looks like the original contact is still stuck inside the original turn signal switch.

There is a second upper contact that fits into a similar hole in the top side of the steering wheel, again spring end goes in first.

The horn is activated when the blue wire (clearly visible in your first picture) coming from the horn relay is connected to ground. The problem is that a wire cannot be simply routed through the steering wheel as the steering wheel needs to rotate... so here is the final part of the horn circuit's electrical path:
1.) Blue wire (from horn relay) in steering column stops at the bottom of the cylindrical bore of the turn signal switch.
2.) The spring loaded lower contact then connects that blue wire to the ring on the bottom of the steering wheel (this allows the steering wheel to rotate without limit).
3.) The ring has a second upper horn contact in the steering wheel visible directly under the horn button. This upper contact has the button end making contact with the steering wheel's horn button.
4.) When you press the horn button, the horn button then makes a connection to ground through the steering column shaft. Since the steering column has a non-conducting 'rag joint' between it and the steering box, a thin and flexible metal connection is there as well to continue the circuit. The remainder of the circuit is through the steering box to the chassis, which of course is grounded. The engineers probably did not want the horn circuit to ground through the steering column bearings alone, so they added that thin metal connection at the rag joint.

You can test your horn and its circuit with the horn button removed by jumping from the upper horn contact (the one in the steering wheel) to the adjacent metal of the steering wheel.

While your steering wheel is removed because you are replacing the turn signal switch, I recommend verifying your horn circuit is OK before you re-install the steering wheel (again, simply jump from the lower horn contact to any good ground).

I have also seen trucks having the steering column so far out of adjustment that the lower contact is not touching the ring on the bottom of the steering wheel.

[robbkramer]

Fantastic! I'll get into this and see what I can do. I have to check but I think the spring contact that had fallen out was from the steering wheel as you describe, and the contact in the column is in fact still stuck in the assembly. Glad I saved all the pieces. This is good! The previous owner routed the wiring to a button in the dash rather than fix this; I don't like work-arounds too much and it sure makes it hard to figure out what's wrong.

I'll let you know if I get all this working: Thanks for the post!

[robbkramer]

OK, all went well with the switch but I'm missing the small "brush" that goes in the steering wheel.. the wheel is also a mess, pieces falling off. At any rate, will order new part for that and then reassemble. I did find out the horn works fine as I accidentally grounded it under the dash and it went off. Good thing I'm not too jumpy or I'd still be lying out there in the cold with bleeding forehead.