Strange Horn Relay Problem - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #1 of 14 (permalink) Old Sep 27th, 17, 11:24 PM Thread Starter
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Strange Horn Relay Problem

I just encountered a strange problem with my horn (70 Chevelle). During the testing of the horn circuit I encountered an issue that makes no sense to me. I'm testing the horn and every time I touched the horn wire to ground the horn relay would click. I then removed the horn relay from the core support and ran a ground wire to the horn trigger contact on the relay, horn worked great. I then reconnected the original horn trigger wire to the relay and the horn still worked great. I mounted the relay back to the core support and now just a click again.

Any ideas what could be the problem?

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post #2 of 14 (permalink) Old Sep 28th, 17, 12:15 AM
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Re: Strange Horn Relay Problem

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Originally Posted by Becker View Post
I just encountered a strange problem with my horn (70 Chevelle). During the testing of the horn circuit I encountered an issue that makes no sense to me. I'm testing the horn and every time I touched the horn wire to ground the horn relay would click. I then removed the horn relay from the core support and ran a ground wire to the horn trigger contact on the relay, horn worked great. I then reconnected the original horn trigger wire to the relay and the horn still worked great. I mounted the relay back to the core support and now just a click again.

Any ideas what could be the problem?
could be a poor ground thru the column.
i would check the horn wire at base of the column connector for horn function
to see if it works there or not before digging deeper

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post #3 of 14 (permalink) Old Sep 28th, 17, 12:26 AM Thread Starter
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Re: Strange Horn Relay Problem

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Originally Posted by VinceS427bb View Post
could be a poor ground thru the column.
i would check the horn wire at base of the column connector for horn function
to see if it works there or not before digging deeper
Sorry, I forgot to say after reconnecting the original horn trigger wire, I went back into the car, grounded the horn wire to the steering shaft and with the relay still hanging, the horn worked. Horn works fine until the horn relay is grounded/installed.
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post #4 of 14 (permalink) Old Sep 28th, 17, 12:41 AM
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Re: Strange Horn Relay Problem

still check it out as suggested
it will indicate which direction to check next
either in the column assy. or forward to the horn relay

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post #5 of 14 (permalink) Old Sep 28th, 17, 12:29 PM Thread Starter
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Re: Strange Horn Relay Problem

Horn works fine until the horn relay is grounded/installed.

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post #6 of 14 (permalink) Old Sep 28th, 17, 1:54 PM
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Re: Strange Horn Relay Problem

There should be no original electrical connection between the mounting tab of the relay and/or the stamped housing cover and I wonder if you have a relay that is damaged electrically to where something inside is shorted to the mounting tab or the housing to where once in place it doesn't work or damaged physically that when bolted into place, something gets shifted and shorted or an electrical path becomes opened up.

For some reason a couple of years ago I replaced the horn relay on my 68 Chevy II Nova and while it is a horn relay it also has another feature as being a key buzzer. When I got the new one it worked on the horn portion but not the buzzer portion but with a little work I got it to work.

https://www.flickr.com/photos/121766...57653574631828

Here's what the guts look like on a 68 horn relay with the key buzzer feature:



I've also seen through the years that the mounting of the horn relay is wrong in that if mounted upside down it can collect water inside the stamped cover and can render the relay inoperable or speed up corrosion to where goofy things can happen such as intermittent function, the horn blowing for no reason, a mysterious battery drain, and so on.

You never know, maybe the relay was munted like this and water got inside of it and damaged it:



I would maybe try just running a jumper wire between the mounting tab of the relay and the radiator support and see if it works. If it does but then bolting it on it quits working, then this leads me to believe something is bent and the force of the bolt on the mounting tab is messing with the relays operation.

I know on my replacement relay it was not difficult to remove the stamped steel cover and maybe take yours off to see what condition things are inside. Who knows, there might be something floating around inside jamming against the contacts.

Jim

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post #7 of 14 (permalink) Old Sep 28th, 17, 4:21 PM Thread Starter
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Re: Strange Horn Relay Problem

Jim,

Thanks for all those possibilities. The strange thing is that just touching the metal case to ground stops the horn from working, still get the click but no horns. I'll try to take the relay apart and see where things might be causing the problem. Else I guess I can either insulate the metal mounting part, leave it hanging or last resort, get a new one.

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post #8 of 14 (permalink) Old Sep 28th, 17, 5:10 PM
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Re: Strange Horn Relay Problem

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Jim,

Thanks for all those possibilities. The strange thing is that just touching the metal case to ground stops the horn from working, still get the click but no horns. I'll try to take the relay apart and see where things might be causing the problem. Else I guess I can either insulate the metal mounting part, leave it hanging or last resort, get a new one.
Troubleshooting things over the internet can be fun.

Are you sure it is the correct relay for the car ?.

I'm not up to full speed with your year and model, but does your horn relay also contain the key buzzer circuit ?.

Just to keep things straight and not to keep going over this but if you have the horn relay not mounted and just dangling in the air and then someone else pushes the horn button on the steering wheel and the horn blows, the second you touch the relay to the radiator support the horn quits sounding while this someone else is still in the car pushing down the horn button on the steering wheel and then if the relay is taken off of the radiator support the horn then again starts sounding ?.

If this is what happening, is there any electrical arc when the relay touches the radiator support and then the horn quits sounding ?.

I know I was curious as to what was inside my combination horn relay/key buzzer and it really wasn't bad taking it apart. The little peened over edges of the stamped tin can were pried open with a screw driver and then when I went to put it back together I was able to hold it and position a screwdriver to tap it with a hammer and peen the spots back over again.

If you can, take some high resolution pictures of the relay as is and then if it is taken apart, take some at that point also. I do kinda wonder if maybe something screwy is going on with the coil inside that pulls the contact points together.

Jim

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post #9 of 14 (permalink) Old Sep 28th, 17, 5:27 PM Thread Starter
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Re: Strange Horn Relay Problem

Troubleshooting things over the internet can be fun.

Are you sure it is the correct relay for the car? It's been in the car for the 15 years I've had the Chevelle. Original as far as I know.

I'm not up to full speed with your year and model, but does your horn relay also contain the key buzzer circuit ? Yes it has the key buzzer and that works mounted or unmounted.

Just to keep things straight and not to keep going over this but if you have the horn relay not mounted and just dangling in the air and then someone else pushes the horn button on the steering wheel and the horn blows, the second you touch the relay to the radiator support the horn quits sounding while this someone else is still in the car pushing down the horn button on the steering wheel and then if the relay is taken off of the radiator support the horn then again starts sounding? Don't have any assistants available, but horn works unattached and when I just had it with the tab in the hole and no bolt, it just clicked.

If this is what happening, is there any electrical arc when the relay touches the radiator support and then the horn quits sounding ?. Unable to test this.

I know I was curious as to what was inside my combination horn relay/key buzzer and it really wasn't bad taking it apart. The little peened over edges of the stamped tin can were pried open with a screw driver and then when I went to put it back together I was able to hold it and position a screwdriver to tap it with a hammer and peen the spots back over again. That helps.

If you can, take some high resolution pictures of the relay as is and then if it is taken apart, take some at that point also. I do kinda wonder if maybe something screwy is going on with the coil inside that pulls the contact points together. I'll try.

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post #10 of 14 (permalink) Old Sep 28th, 17, 6:00 PM
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Re: Strange Horn Relay Problem

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Originally Posted by Becker View Post
Troubleshooting things over the internet can be fun.


Just to keep things straight and not to keep going over this but if you have the horn relay not mounted and just dangling in the air and then someone else pushes the horn button on the steering wheel and the horn blows, the second you touch the relay to the radiator support the horn quits sounding while this someone else is still in the car pushing down the horn button on the steering wheel and then if the relay is taken off of the radiator support the horn then again starts sounding? Don't have any assistants available, but horn works unattached and when I just had it with the tab in the hole and no bolt, it just clicked.
A lot of times I need a second person also but do you have any of the alligator clip end test leads ?. One could attach one end to a ground and the other to the activation terminal of the relay and then you could touch the relay to the radiator support to check for an arc. You might do this during the day so as not to annoy your neighbors too much with a blaring horn.

Jim

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post #11 of 14 (permalink) Old Sep 28th, 17, 11:36 PM
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Re: Strange Horn Relay Problem

I was mulling this over some tonight and let's say for some reason the output of the horn relay inside is shorted to the case of the relay.

If this were to happen then with it not mounted, the activation wire from the steering wheel contacts sends a ground to the relay and it then closes the contacts inside and it then sends the signal to the horn and it then makes noise.

If for some reason the output of the relay inside of the relay were to be in contact with the case of the relay, then once it's mounted, then when the relay closes it may very well be make a clicking sound as the contact points close but now the output which should be going out to the horn is now shorted to ground and now the horn cannot get 12V and it does not make sound.

I'm wanting to start laying my bet on a bad relay as somehow inside I'm thinking it's output to the horn terminal is shorted to the case of the relay. This would be evident if with the relay activated unmounted the horn sounds but once the relay case or it's bracket becomes grounded a short occurs stopping the voltage from reaching the horn and then the horn stops sounding. When this occurs then it having a dead short may never blow the fusible link off of the battery as during the tests you are not holding down the horn button on the steering column for very long. With the test I described earlier then an arc would appear when the relay becomes grounded to the radiator support and then the horn stops sounding.

Jim

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post #12 of 14 (permalink) Old Sep 29th, 17, 5:29 AM
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Re: Strange Horn Relay Problem

I think Jim nailed it in the above post..
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post #13 of 14 (permalink) Old Sep 30th, 17, 2:17 AM Thread Starter
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Re: Strange Horn Relay Problem

Thanks for all the thoughtful input.

I cleaned the horn relay outside and in, used a little Emory on the contacts and the horn is working exactly as it should.
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post #14 of 14 (permalink) Old Oct 1st, 17, 1:39 PM
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Re: Strange Horn Relay Problem

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Thanks for all the thoughtful input.

I cleaned the horn relay outside and in, used a little Emory on the contacts and the horn is working exactly as it should.
I'm glad you got it working and I have to think that cleaning the contacts was not the issue of it working when the relay was not mounted and then not working when mounted.

I kinda wonder is there was some junk floating around inside that become dislodged and is no longer there or maybe the stamped cover was hitting something and from removing it and putting it back on, the issue became resolved. Who knows sometimes.

Anyway, I'm glad it's working once again.

Jim
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