Never thought a Horn could be so challenging

[DetroitIron]

After hours of researching this site and others why the horn on my 85 K20 doesn't work, I wondered if some experts might be able to narrow it down.

Here's what I've done/tried:
1) The horns work when running a jumper wire from the battery
2) The horn fuse is good and I'm getting 12 volts measured with a multimeter in the horn fuse location under the dash
3) My horn relay clicks (does that mean it's for sure ok?) when I push the horn button
4) Pulled my wire harness bulkhead connector and checked continuity of the horn wires running from firewall to horns. All good there.

Any ideas? Thanks for any help you can offer.

[blackbeaSSt]

tell me about it man. i got a 88-94 steering wheel on my 82. i go the lead wire but apparently the middle clip is always touching the center bolt so there's stopping it when i put the cap back on

i resorted for the time being to drive with the cap off and a long screw to put in there if needed.

hope you get it working

[babyJay]

The auxillary contacts in the relay could be bad. I've seen relays with the swinger blown clear off. Check it with a volt meter on the CONTACTS side. You should have voltage always on one side, and voltage on the other after you hear the "click". Can't help you with the terminal numbers though, sorry.

[sumran]

Did they work before and suddenly stop working? Sounds like a bad relay to me. Luckily they are cheap to replace.

[DetroitIron]

Thanks guys. I bought the truck a year ago with the horn not working. Question on the horn relay...can it be bad or the cause even if I can hear it click when the horn button is pushed?
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[1LowToy]

The clicking of the relay means your horn button is working. Your horns work when fed juice. The relay is being activated when the horn button is pushed, and is not relaying the juice to the horns when activated. Replace the relay

[Gyawo]

To confirm the relay being pooched you can always jump where the relay plugs in. Find where your power is coming from and to which one it goes and jump it. HONK! and you know your relay is bad.

[DetroitIron]

Originally Posted by Gyawo

To confirm the relay being pooched you can always jump where the relay plugs in. Find where your power is coming from and to which one it goes and jump it. HONK! and you know your relay is bad.

I was checking how to do this.....I can pull the horn relay out enough to slip a piece of paper clip behind the relay (yet still plugged in some) to bridge across two of the three metal prongs..... Then push the horn button or should it honk just by jumping it?
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[sandorjoben]

I had a similar problem when I got my truck, my issue ended up being corroded/patina'd connectors that clip onto the horn contact. But... check the relay if that doesn't work, check the connectors at the actual horns behind your grill, you can check them with a test light if you want to, when you honk the horn, the test light should illuminate.

[Gyawo]

I was checking how to do this.....I can pull the horn relay out enough to slip a piece of paper clip behind the relay (yet still plugged in some) to bridge across two of the three metal prongs..... Then push the horn button or should it honk just by jumping it?

A paper clip should work, as long as it conducts electricity, but it will get pretty toasty so it is best to do it with a jumper wire if you have one. You can take the relay out completely, you do not need it in to jump it. Find out where your power is coming from and jump it to the contact that would complete the horn circuit. I do not have a wiring diagram from an '85, nor do I know what the diagram on the relay looks like so I can't give you a for sure if you have to press the horn or if it will honk as soon as you jump it. Best way to find out is to give it a try and let us know!

If you have a wiring diagram you can see if there is a wire that goes into the relay that is hot at all times, if it does say that then you will not have to push the horn, it should honk when jumped. Let us know how it goes.

[DetroitIron]

For only $6 I decided to pick up a new horn relay...still no honk. Dang. Not sure where to check next...I keep thinking that my horns work when jumped off the battery AND I have 12 volts when I probe the horn fuse location with a voltmeter in the fuse box....hmmmmmm..

[sumran]

If it never worked the wiring could be incorrect. People put the wires on the wrong terminals. There should be a diagram on the relay that shows the function of the relay. It is a normally open set of contacts that is closed by the horn button.

If you can attach a picture of the relay and wires you would get a quick answer to correct connection. I'm sure there are many on the the site that know the wiring on the relay without the picture. I am not familiar enough with these truck to know without the picture.

[DetroitIron]

Originally Posted by sumran

If it never worked the wiring could be incorrect. People put the wires on the wrong terminals. There should be a diagram on the relay that shows the function of the relay. It is a normally open set of contacts that is closed by the horn button.

If you can attach a picture of the relay and wires you would get a quick answer to correct connection. I'm sure there are many on the the site that know the wiring on the relay without the picture. I am not familiar enough with these truck to know without the picture.

Thanks. I will work on some pics of the fusebox and relay location.
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[DetroitIron]

As Randy suggested, I'm attaching some pics I took tonight of my fuse box (top left yellow fuse is for the horn). The next is of the new horn relay installed front view and then best I could get of the side view. Also took a pic of the bulkhead connector removed on the firewall under the hood with a thin screwdriver pointing the the space connector that corresponds to the wire that runs to the horns. Appreciate any thoughts on how to troubleshoot at get this thing honking again....Thanks very much...

[DetroitIron]

other pics...new horn relay (grey) above the hazard flasher relay...

[DetroitIron]

more..sorry I'm new at uploading these pics.

[DetroitIron]

bulkhead connector under the hood on firewall

[Gyawo]

Did you check for continuity from the firewall to the relay side of the circuit? You said you had checked from the firewall to the horn and it was good, but what about that?

[DetroitIron]

Originally Posted by Gyawo

Did you check for continuity from the firewall to the relay side of the circuit? You said you had checked from the firewall to the horn and it was good, but what about that?

I will try that...I will have to figure out which of the three female spade connectors on the horn relay plug in spot go to the firewall/connector via wire. Hopefully I'm getting closer to the problem. Now assuming that is the bad link, how do I go about replacing the wire?
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[sumran]

I would check continuity from the terminals on the base to the connection at the horn. Check for 12v on the base terminals you should have a constant voltage on at least one of terminals. You should get 12v on another terminal when you push the horn button. If all of those conditions test properly, you either have the wrong relay for your base or you got a bad new relay (this happens more often than you think these days). Match up the diagram to the terminals you have identified.

Usually, the problem is the relay. The other common problems occur at connectors.

[cr34t3d_by_d4rkd3n]

http://forum.73-87chevytrucks.com/sm...?topic=11766.0

[DetroitIron]

Thanks for the additional advice. Spent a few hours last night confirming continuity in the horn wires from BOTH bulkhead connectory on firewall to horns AND bulkhead horn spade connector on the firewall to the horn relay mount under dash. Also, checked for 12 volts hot power to the horn relay block after unplugging horn relay. So my wires appear not to have breaks, I'm getting 12 volts to the fuse panel and the horn relay block, i have changed horn relay....After all this last night and getting things put back together.....NO clicking sound from the relay under the dash....the only thing I can think of that may have smoked something is I used a short 3" piece of wire to try and jump in the horn relay black connectors with the horn relay removed (ie tried jumping the hot to green, hot to horn button wire, etc.)...could this have done something to the ground wire running up to the horn button in the column?? grrrrrrr so frustrating, but I'm not ready to give up...any and all help/suggestions is very appreciated. I emailed the PO and asked about the horn....it never worked for the 2 years he owned it either...the original owner is deceased now. How could I check continuity from horn relay block to horn button?
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[DetroitIron]

One other thing, would the fact that my horn relay was clicking before mean that the horn button and wire down the column is/was fine or had continuity?
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[DetroitIron]

After all the suggestions and checking every wire/connection with multimeter, I have found my problem with why the horns don't work. See picture...with my steering wheel removed down to the turn signal switch...there is a little brass boss that is spring loaded not making contact with the other parts of my horn assembly (second pic shows plastic cup that fits on top of brass boss...there's a gap between the brass piece on the underside of the plastic cup and the spring loaded brass boss). It seems as the spring underneath is not extending the brass boss out enough. It won't slide out either to allow me to stretch the spring. When iI jump wire from the boss to the steering shaft....YAY...the horns blow loud. I don't want to yank and break that whole turn signal connector. Any suggestions, please. I'm almost there I think.

[DetroitIron]

Hooray! I figured it out. Just in case anyone has the same issue in the future and finds this thread, here's what I had to do. From the pics I posted last night, I removed the three screws that hold the white turn signal switch and carefully pulled the wire clips from it using a tiny flat head screwdriver. This gave me enough room and access to the back side of the turn signal switch. I very carefully removed a small metal cap on the back of where my screwdriver is pointing to the brass boss that is spring loaded. I removed the small spring from insided the plastic hole and gently stretched it out....it's brittle so be very careful. Put it all back together and this increased spring allowed the brass thing to stick further out and make contact with the back brass ring think I'm holding in pic #2. I like having horns now just in case of emergency. Hope this threasd will help someone in the future. Thanks.