Horn Problems

[landy]

Still having some horn problems. Now I know why the P.O. must've disconnected the horn.

With 12 volts applied directly to the horn it works. Replaced all the column horn components, grounded the steering wheel button and no horn. So then replaced the horn relay, grounded the horn button and got some buzzing and some smoke. Checked the horn relay and it had a hole burned in the side of it, so I know there's a short in the circuit somewhere, but I'm not sure where to start. I have one horn with a non-original wire running to the terminal The factory wiring diagram seems to indicate that a wire should go from the horn to the fuse panel. Is that correct?

Thanks!

[JimKshortstep4x4]

There are three wires connected to the horn relay, 1 large green which routes from the horn through the fuse panel directly to the relay, 1 large red which is the power wire, and 1 small black wire which comes from the steering column. The small black wire activates the relay and grounds the relay when the horn button is depressed.

If all of the wiring is intact then the green wire would be the wire to cause the short since the relay sends power to it when it is activated. I would disconnect the green wire at both ends and using an ohm meter check the resistance to ground. If resistance is low then a short is indicated. If a ground of the green wire is indicated then check the harness by stripping the tape back and inspect the green wire from the fuse panel to the relay.

If any wires are cobbled in the harness, check those, also. The factory horn wiring is well designed and from what my experience has been it is trouble free.

Jim

[landy]

Looking more closely, I found the non-original wire that goes from the horn through the dash isn't connected to anything, so there's no power to the horn.

To confirm, the green wire from the relay as originally wired should have connected directly to the horn?

[Stocker]

Originally Posted by landy

To confirm, the green wire from the relay as originally wired should have connected directly to the horn?

Yes.

[landy]

Still having horn problems. I've replaced the relay, signal switch, and cancelling cam. When I put the cancelling cam onto the steering shaft and push it down, the bottom brass part of the cancelling cam contacts the edge of the turn signal stalk, grounding out, and the horn goes off.

I'm not clear on how the horn components inside the steering column are supposed to work, so maybe I'm missing a part? But I don't think so, because I've compared the parts diagram in the LMC catalog and the repair manual, and it looks like I've got everything.

I understand that when the barrell shaped copper button is pushed down and grounded the relay/horn is activated. And I'm assuming that the bottom of the cancelling cam shouldn't be contacting anything other than the copper button. There's very little clearance between the brass bottom part of the cancelling cam and the edge of the turn signal stalk - maybe there's a spacer or spring I'm missing? It's a non-tilt column, BTW.

Could I get an explanation of how the horn parts inside the steering column work?

Thanks!

[Big Daddy 70]

I'm not sure if this will help, but I recently changed my steering wheel, and found I had put the flexible piece in backwards, so it didn't pop back correctly.

I had the following components when I took it apart, in this order:
Horn button
Ring with plastic insert
Flexible piece
Nut/washer

Hope it helps.

[LSUMurse]

I am definitely not an expert in this area, but could it be a short in the horn itself? Maybe it's shorting inside the horn assembly. Smarter people than me will have to weigh in, just a thought.

[landy]

Well, I'm obviously no expert either, so all suggestions are appreciated. I don't think it's the horn since it works when I apply a direct 12 v source to it. And I think the wiring is ok from the steering column to the horn relay. Perhaps a problem from the relay to the fuse panel to the horn?

I think if I can get a better understanding of how the steering column horn components work, I'll have a better chance of diagnosing the problem.

[68 P.O.S.]

Here's another old thread on it.

http://67-72chevytrucks.com/vboard/s...d.php?t=229041

[landy]

Without the cancelling cam installed, I put the steering wheel onto the shaft and the back middle steel part of the steering wheel touches the copper button and the horn goes off. So even without pushing the copper button down, which apparently is supposed to send current to the relay, the circut is being completed. There's got to be short somewhere, right?

On a related matter, my steering wheel seems way to close to the upper steel column piece. The back part of the steering wheel is rubbing on the steel column piece. This truck had a small diameter after market steering wheel when I got it, and all the horn components were missing as well. I bought a used 2nd gen steering wheel to replace it with. Is there a spacer of some sort. But if there was, the shaft wouldn't be long enough for the steering wheel to fit onto. Any thoughts?

Thanks!

[landy]

Bump

[LockDoc]

Originally Posted by landy

Without the cancelling cam installed, I put the steering wheel onto the shaft and the back middle steel part of the steering wheel touches the copper button and the horn goes off. So even without pushing the copper button down, which apparently is supposed to send current to the relay, the circut is being completed. There's got to be short somewhere, right?

On a related matter, my steering wheel seems way to close to the upper steel column piece. The back part of the steering wheel is rubbing on the steel column piece. This truck had a small diameter after market steering wheel when I got it, and all the horn components were missing as well. I bought a used 2nd gen steering wheel to replace it with. Is there a spacer of some sort. But if there was, the shaft wouldn't be long enough for the steering wheel to fit onto. Any thoughts?

Thanks!

It is working correctly then. The copper piece is not a button, it is a ground. You are not understanding how the horn circuit works. The tower with the copper contact goes through the hole in the steering wheel and the contact touches the round metal disk in the horn button assembly. Unhook the battery until you get it all put together then hook the battery back up.

LockDoc

[landy]

You're right, I don't understand how the horn circuit works. I also didn't know the copper button or tower goes through the steering wheel, so I'll give your suggestion a try.

On a related note, I'm wondering if the steering wheel I now have is too thick. The truck came with an aftermarket small diameter wheel with all the horn components missing. I bought a used 2nd gen steering wheel to install. With the cancelling cam installed and then the steering wheel, the wheel is barely on the splined portion of the shaft. The wheel is way too wobbly because it's not adequately seated down far enough on the shaft. Without the cancelling cam installed, the wheel seems too close to the steel outer column, almost rubbing against the column.

Is there a difference in thickness between the 1st gen wheels and 2nd gen wheels? Were there different thicknesses of cancelling cams?

Thanks!

[LockDoc]

Originally Posted by landy

You're right, I don't understand how the horn circuit works. I also didn't know the copper button or tower goes through the steering wheel, so I'll give your suggestion a try.

On a related note, I'm wondering if the steering wheel I now have is too thick. The truck came with an aftermarket small diameter wheel with all the horn components missing. I bought a used 2nd gen steering wheel to install. With the cancelling cam installed and then the steering wheel, the wheel is barely on the splined portion of the shaft. The wheel is way too wobbly because it's not adequately seated down far enough on the shaft. Without the cancelling cam installed, the wheel seems too close to the steel outer column, almost rubbing against the column.

Is there a difference in thickness between the 1st gen wheels and 2nd gen wheels? Were there different thicknesses of cancelling cams?

Thanks!

I don't know about the wheels but I'm sure the cams are different between the old and new.

I would take that wheel off and get a stock one. At least until you get everything working correctly.

LockDoc