Is it just me, or are the things that go wrong with anyone else's car always the things we have the least expertise on?? For me that means electrical.

Had some "help" over recently who temporarily moved the horn relay out of the way to get access to something else apparently without disconnecting the battery. Saw the electrical arc out of the corner of my eye, of course he fried the relay. Replaced it with a new one, horn worked fine again.

Then over the last couple of weeks I noticed that the horn would operate more and more intermittently. By varying where I pushed on the horn button (Grant wheel and button) I could sometimes make the horn work. Then it stopped working altogether.

Seemed obvious so I replaced the horn button, still doesn't work. Good ground on the button. 12V applied directly to the horn lead makes it beep. Relay is new. :confused:

So what does anyone suggest?? Do I have a relay that gradually crapped out? Any suggestions would be more than welcome.
Thanks.

66 Chevelle I assume.

Shorting out the hot wire on the relay shouldn't hurt the relay at all but might blow the fuse or fusible link in it's power wire voltage supply circuit.

There are two basic circuits in the relay,
1) a 12 volt power supply powering an operating coil which gets it's ground from the horn button.
2) a set of contacts with power feeding one contact and the horn wire connected to the other contact.

When the operating coil gets a ground signal from the horn button it energizes the relay which pulls together the set of contacts.

Pretty simple to check out by grounding the black horn button wire.

Not sure of a 66 has the pink key buzzer wire but I'm pretty sure it doesn't.

When you say they don't work , do they make any noise at all ? When horns are going bad they can become interminent. They fill up with rust and the diaphram can't vibrate. Don't hit them with hammer, this makes a dented horn that doesn't work. Dean has the wiring right. As said ground the side of the relay going to the wheel, then move down the circiut. Gary

To expand on what Dean said, Push the horn button and listen for the horn relay to click (energizing the relay). If the relay clicks the problem is in the relay unless you measure 12 Volts in and out of the relay contacts while the relay is energized. If no click Check the ground side of the relay coil . If you ground the GROUND lead to the relay coil (the one going to the horn button) you should hear the relay click and you should have 12 Volts to the horn through the relay contacts (make sure it's not the hot side of the relay coil or grounding it will be instant death for the fusable link). In any case pushing the horn button or grounding the ground lead to the relay coil should energize the relay.

I agree with Dean. Shorting the wire creates a big current draw to ground but should not harm the relay or horn. Fusable links can go bad with no visual evidence. Look for the fusable link to the relay coil and check both sides of it for 12 Volts. You can buy a replacement from an auto supply if you aren't concerned about the harness being correct.

Good Luck
Chuck

Thanks for all the detailed input, very much appreciated. Will give it a try and see if I can diagnose it.

Couple follow-up questions:
1) If it's the fuse (don't see any blown ones), wouldn't the non-functioning happen all at once instead of the gradual decline I had?

2) Where is the fusable link located? My '66 had been modded before I got it and the harness is a combo of stock and Painless components. Where should I look?

Hornworks - - the horn blows strong if you apply 12V directly to it so I know it's not the horn itself.

Thanks again.
Bob

OK, I've checked the fuse panel (all good). Can't find the fuseable link that's been mentioned. I've replaced the relay again (cheap, easy) and the horn button is also new. The horn itself is good, it beeps when you apply a 12V source directly to it.

So all I can figure is it's this fuseable link. Anyone know where to look for it or have a pic of it? Don' see anything obvious under the dash.

Any help would be appreciated.

Hi Bob, in electronics we call it divide and conquer. Go to your horn relay and the coil has 2 wires ,1 is the 12v source the other side goes to the steering wheel. you need to ground the wire going back to the wheel. if the horns work ,you now have divided the circuit and
know for sure that your problem is between the steering wheel and the relay. Some times the fuse links are wrapped in the harness. Next I would remove the plug from the firewall and use a ohm meter to see if you have continuity between the bulkhead plug conection and the wire to the relay. If that is open it is in your harness if it is ok look at the steering wheel . Dividing circuits is best way solve electric problems. I see that your 1st post talks about a arc by the relay. Also look at the crimp conections on the plugs going into the relay. If you short out a relay, it will smoke. Gary

If the fuse/fusible link were blown there would be no power to the horn relay.

Does ANYTHING happen when you ground out the small black wire?

Gary / Dean -

Thanks for the replies. When I ground the black wire going to the horn button, nothing happens. No horn blow, no click at the relay.

At the relay it looks like this. On the 'screw down' connectors for the relay coil there's a red power lead and a black wire I'm assuming goes to the strg wheel. At the bottom of the relay there's a green wire that goes to the horn (if I apply 12V to it the horn beeps) and another black wire. A third spade connector has no connection which I believe would be for a key buzzer which my car doesn't have. I know the connections are correct in orientation since the horn worked correctly once I replaced the old relay.

I'll go with the divide and conquer strategy and see what I can find. The previous owner didn't do me any favors when he put a partial Painless harness inm the car, would have been easier if he'd replaced it all. Thanks again for the help. I hate electrical ghosts, give me a mechanical problem any day. The last one I had (alternator) I chased forever because the new replacement alternator I got was bad right out of the box, so that gives me pause about the new relay and horn button too.

Bob

Ok Bob , now we are getting somewhere. Not knowing which conectors are which on the relay , I would pull the cover off one of the units and identify which terminals we are dealing with for sure.The coil we are dealing with is thin lacquered wire wrapped around a core. Follow the 2 ends of the coil to the terminals. One should have 12v all the time and the other goes to the wheel. Check for 12v with a meter or test lite and let us know. Gary

Finally had a few minutes to dig into this a little more. Let me start my clarifying that in my last post when I said I grounded the black wire going to the horn button, I meant the one literally that connects at the horn button, not the one at the relay. If I misunderstood your instructions, Gary, did that now cause another problem? I don't find any blown fuses in the panel.

Following the suggestions more carefully I grounded the black wire at the relay that goes to the horn button. Got a very loud horn blast as my reward and confirmation that the problem is between the wheel and the relay, so I moved onto the next suggestion. I pulled the firewall bulkhead connector and confirmed continuity in the harness to the relay, so now the problem is between the wheel and the other end of the bulkhead fitting.

I pulled the wheel again, nothing obvious. As a reminder I'm using a Grant wheel with one of their horn buttons. The only thing I noticed is when I pulled the wheel and bolt-on adaptor, the black lead wire that feeds into the press-on hub goes into a spring-loaded contact mechanism of some sort from the original wheel. When I first pulled the wheel I noticed that contact spring was not moving, and eventually it loosened up and now moves freely. Didn't have the time to pull that out and check into it, can that piece be an issue?

Checked under the column and dash, didn't see any obvious breaks in the wire or connectors until it disappeared into a group of wires bound up in electrical tape, didn't have time to unwind it.

The thing that keeps coming back to me is that the horn gradually stopped working, it didn't stop all at once. I could move the pressure point on the horn button and get it to beep until it finally quit altogether, which is why my first inclination was to replace the button. I suppose it's possible the old button died and the new one is also bad; it wouldn't be the first time that's happened to me on an electrical issue.

So Gary / Dean / other electrical wizards: comments / next step?

Thanks.
Bob

OK, if grounding out the small black wire AT the steering wheel end does nothing but grounding out it's end AT the relay causes the horn relay and horn to work then the wire has to be broken somewhere.

Sometimes the ground straps at the rag joint loose their connection. :confused:

I think Dean is on to something, check the rag joint first. That is easy ,just jump a wire across it. If your column is like the 69 and up that I am familiar with ,there is a white colar around the center of the column under the wheel. It cancels the turn signals and connects the horn button into the wiring through a tube. That could also be a problem. Gary

Thanks, guys. Will look into that and advise!

Bob

OK, finally got a chance to dig back into this. Pulled the wheel again, black wire still properly connected to the Grant horn button. The other end of that black wire has a contact that seats on a spring that slides in a brass test-tube-shaped housing that is sealed on one end. That brass tube goes into a plastic tube of sorts that is seated in the press-on cast hub.

The spring was broken in two so I stretched the remaining portion (didn't have to stretch it much) and reassembled the wheel; still no horn function. As far as I can see/tell, the black horn lead doesn't go any further than contacting that spring. With that corrected and the horn still not working, where do I go next? Remember that I've isolated the issue to be between the wheel and the bulkhead connection inside the car; all segments under the hood test good.

Any advice is appreciated.

Find instructions for Grant wheel on line. Remove wheel and test black wire coming up column at signal light switch and canceling cam (green plastic with brass contacts). Ground out here and see if horn sounds. Grant horn buttons aren't known for their dependability.