Horn trouble

[Brandon]

I'm trying to figure out why my horn isn't working.  If I hookup the horns to the battery directly, both the high and low sound great.

Where is the relay located?  Any tips on taking off the horn cover and/or steering wheel?

[JD]

The horn button and wires in the steering wheel on '67's are notorious for issues.

You carefully pry the horn button assembly out of the center of the wheel with a thin flat pry tool.

Most likely the wires from the horn button trough the steering wheel is the problem.  On the old forum there was a fix posted, maybe some one can post it again.

[Bob Gaines]

I'm trying to figure out why my horn isn't working.  If I hookup the horns to the battery directly, both the high and low sound great.

Where is the relay located?  Any tips on taking off the horn cover and/or steering wheel?

I would be glad to help . tips to taking cover off, wheel removal,  testing ,repair ,etc. it is too much typing for me. I will send you my phone number . After we discuss it and if successful you can recount your steps.

[557]

One thing is for sure.Use a plastic tool(I use a pot scraper) to remove the horn button.Metal can chip plating.

[Brandon]

With Bob's help I was able to isolate the problem down to the wires in the horn button trough the steering wheel.

Can anyone recommend a particular solder type for soldering the new wire I'm going to run to the ring?

[Brandon]

Have my horns running again!  I had at least 3 different problems, so I'll post here for posterity.

First thing I did was jump each of the horns from the tabs directly to the positive battery terminal.  They both honked, so the problem had to lie between the horns and the horn button.

Now the horns are grounded through their mounts.  Bob Gaines gave me a tip here.  Unbolt the horns and sand off the paint on the the bracket and the face of where it mounts against.  He also recommend putting a piece of aluminum foil sandwiched between the bracket and mount which helps with the contact.  I applied some dielectric grease on both sides of the foil and re-bolted them on.  Horns still not working, but I know I have good grounds now.

On to the horn button.  After popping it off, refer to the picture to see how this works:



Under the cap, you can see a black piece of metal, a copper disc in the center, and an insulated spring between the metal and copper disc.  The black piece of metal is tied to the red wire behind the cap, which goes through the steering wheel, and is soldered internally to the inner metal ring.  The copper disc is tied to the white white, which goes through the steering wheel, and is soldered internally to the outer metal ring.

Here's what things look like with the steering wheel removed:



There are two copper contacts in this picture.  They are attached to shafts, which are attached to a piece of metal with a wire crimped to it, and there is a spring on each of the shafts that holds them out to touch the circular rings on the back of the steering wheel.

The one on the top right (tied to the yellow wire), makes contact with the outer ring of the back of the steering wheel.  The one on the bottom right/center (tied to the blue wire w/yellow stripe), makes contact with the inner ring on the back of the steering wheel.  Both wires run down the column to a connector under the dash.  The yellow wire continues to the fuses, which go back to 12V at the battery, while the blue wire w/yellow stripe continues to horns.

Now back to the first image.  When you press the button, the large spring compresses, which pushes the black metal at the center down to make contact with the copper disc.  When that happens, 12V flows from the battery, through the fuses through the yellow wire up the steering column, through the outer contact ring to the white wire through the steering wheel, through the copper disc, through the black metal piece, through the red wire through the steering wheel to the inner contact ring, through the blue wire w/yellow stripe down the steering column, over to the low horn, following over to the high horn next to the battery.

Hopefully that was relatively clear.


Now here's I diagnosed _my_ problem(s).


Once I got the horn button off, I used the FSM to get the color coding of the wires at the connector.  I then tried to get continuity from the horns to the connectors at the bottom of the steering column and had a hard short (good).  I then checked continuity between the yellow wire at the bottom of the shaft and the white wire at the steering wheel.  I had about 50K-70K resistance, and it jumped around, which is bad.  I then checked the continuity between the blue wire w/yellow stripe and the red wire at the steering wheel.  It measured around 200 ohms of resistance.  Much better, but still not ideal.  So I took off the steering wheel.

Bob Gaines helped me with this, and it goes as follows:
- Make sure your wheels are straight and your steering wheel is centered.
- Unscrew the nut attached to the steering wheel, but only unthread it to the end of the shaft.  So it'll be loose but still screwed on the shaft.
- With one person pulling on the wheel, have another hammer with a flat attachment on the shaft, and the wheel should come lose.
- Finish unscrewing the nut and pop it off.

Now I checked continuity again at the rings on the back of the wheel, and I got similar measurements, which clearly changed as I moved my meter around the rings.  It was covered with crud!  I used a few rounds of lacquer thinner to clean the gunk, then followed up with steel wool.  Now I had good hard shorts between the front and back of the steering wheel, so I put the wheel back (not bolted down) and re-checked my measurements.  I now had a hard short on the yellow wire at the bottom of the column to the copper ring, but still had high resistance between the blue wire w/yellow stripe and the black metal.  I pulled the wheel off again and measured the continuity between the copper contacts down the column.  I got hard shorts here too.  So I pressed each of the contacts down, and noticed the inner contact did not return all the way up.  I could pull it up by hand, but the spring was clearly worn.  I measured the OD of the spring, ran to Ace HW, and got a match.  I then pushed the spring back on the shaft, coiled my new spring around, clamped it down around the shaft, and let the original spring loose.  I now kept turning on the spring and resetting the shaft until about 4 wraps when the spring would return all the way to the top by itself.  I then cut the end of the new spring off which now keeps it at the correct distance.  Put the wheel back on again, and got hard shorts all the way though the column.  I then jumped the contacts on the top of the wheel, and I got some piddly honking, but no real horn.  Darn.

I now started checking for voltage drops.  I had 0.284V at the yellow wire at the bottom of the column, which isn't great, but still had 0.285V at the low horn connector.  So it seems like there's a lot of drop somewhere between the battery and the bottom of the column.  Since I still had 12V at the horn connector, I jumped the horn contacts again, and noticed it dropped to about 6.6V.  That's clearly a lot of current!  I unmounted the horns and put them on a bench.  The FSM says they should be between 3.5A and 5.5A at 12V.  I was seeing 6.5A on the high horn and 7.25A on the low horn, which is too high!  There is a screw on the back you can use to adjust this.  Turning right (tightening) reduces the current.  I turned them down to about 4A each and put them back on the car.  Jumping the wires again, and, Honk-Honk!

I still need to go back and find the source of the voltage drop, but my horns are working, so it'll have to wait until I have the time.


Hoping this helps somebody...

[csheff]

Thanks Brandon, that will help a lot of us.

[oldcanuck]

This will help me as well as mine are not working.

Something else mine is doing...... when I center the horn button on the wheel, it somehow rotates off center immediately after driving ? This seems odd as it is quite tight removing and installing again and again..... what am I missing....?

Thank You,

BG

[The Going Thing]

The horn button always rotates off-center. The clear button portion has nothing locking the tabs from rotating. The horn itself is the ground.  Many times the paint isn't removed from the horn mounting bracket and at the core support. The horns will not sound or they are very weak when this is not addressed.

[Brandon]

As you can see from the picture I posted, it doesn't matter if it rotates, the spring will still work from any rotation.

As "The Going Thing" says, the most common problem I've heard of is the paint on the bracket.

[oldcanuck]

Funny thing.... I just went into the garage and checked mine..... my horn button/clear plastic button will not rotate in the housing... it will start to move but only about 1/4 inch each way ?

I am going to check my horn grounding as this GT-350 was painted about 15 years ago.  Does it matter which lead to connection on the button wires ?

[Bob Gaines]

Funny thing.... I just went into the garage and checked mine..... my horn button/clear plastic button will not rotate in the housing... it will start to move but only about 1/4 inch each way ?

I am going to check my horn grounding as this GT-350 was painted about 15 years ago.  Does it matter which lead to connection on the button wires ?

I always help the ground at the connection point of the radiator support by sanding off the paint underneath where the horn bolts on and the backside of the horn bracket. I also take a small amount of aluminum foil and wad it up to sandwich between the horn bracket and the radiator support to fill any gap there might be. It doesn't take but a small amount of foil. I also put dielectric grease on the bare metal surfaces to protect them before bolting together. It doesn't matter which steering wheel horn wire goes to which horn button connection. 

[The Going Thing]

I might also mention too that I worked on a wheel that the contact on the wheel was rubbing the post to the point it was causing copper particles. There were enough that it coated the wire contacts on the emergency flasher switch and grounded it out. it melted it. I have even seen a few where the plastic insulator tubing the turn signal switch harness runs through is missing. Another potential issue. There is also a specialized tool for removing pins from the blocks. Stop being cheap. Spend the 14.00 and buy one if you're going to do your switch. If you know nothing about electrical, leave it alone and pay a professional. The tool is available from Amazon as well as NPD. I'll post the links below.
Always be sure to inspect the switches as they are not a protected circuit and can easily cause a fire when shorted.
Amazon
https://www.amazon.com/Lisle-56500-Terminal-Tool/dp/B0009OR906/ref=sr_1_2?dchild=1&keywords=lisle+electrical+pin+removal+tool&qid=1585863905&sr=8-2

NPD
https://www.npdlink.com/product/removal-tool-wire-terminal-removes-wire-terminals-from/107213?backurl=search%2Fproducts%3Fsearch_terms%3Delectrical%252Bharness%252Bpin%252Btool%26top_parent%3D200001%26year%3D

[oldcanuck]

Thank you Bob.

[S7MS427]

The last time I replaced the turn signal switch I used an old ball point pen refill I had laying around to remove the pins from the connector housing.  Worked perfectly.  The one I used was made of brass (I said it was old).  Unfortunately new refills are made of plastic and I doubt they would do the trick.  I did save it and put it in my tool box.