There is a very large class of people that own 65/66 Mustangs that, as far as I can tell, anyway, have been, for the most part, ignored entirely. They don't really want that 100 pt. show car that is so nice and was soooo expensive that they're afraid to drive it, they also don't want to make their car capable of achieving warp factor three. They just want this car that they dearly love to be able to cruise around smoothly and reliably, without having it dump them out on the side of the road or have it start making weird noises or belching out big clouds of funky-smelling smoke. And I think, truth be told, that this is by far the largest class of Mustang owners. They take their car to some technician when what they actually need is a mechanic, and this, frequently, does not work out very well at all for the owner. They don't want to re-engineer the entire car, they just want someone to fix what broke. These are the people that I am trying help out with this blog. Some problems require a little bit of back and forth, as in, "Try this." "I tried that and it didn't change anything."
" Oh. well, you probably need to try that." " I tried that and it helped, but it still isn't quite right." "Now you need to try this...." If you go to http://www.allfordmustangs.com/ and then go to the classics forums, you will be able to do that with a pretty hefty gathering of some very knowledgeable people that also happen to be very friendly. None of that ridiculous one-upmanship, no flaming or abuse, none of that stuff. Just good, solid advice from people that know what they are talking about.

Saturday, March 29, 2008

1965 and 1966 Mustang horn wiring and troubleshooting

Here is how your horns are supposed to be. The first diagram is the 64 1/2 horns, which have a horn relay and only one wire for a contact in the turn signal switch. I'll talk about those in a later post. Right now you can only see part of the wiring diagrams, but, if you click on one of them, the rest of it will show up.  The rest of this is post is for the 65/66 cars that have an alternator instead of a generator.

The first picture is the wiring of everything horn-related that isn't right behind the steering wheel. The last picture is a new turn signal switch. This one is the switch for a 68. I used it because the only new switches that I could easily find were all 68s, but the part concerning the horns is the same as a 65/66. The arrows are pointing to the horn contacts in the switch. The one with the yellow arrow is the one supplying power to the horns and the one with the blue arrow is the one that takes the power from the switch out to the horns themselves. The third picture is the back of a steering wheel. This is an 85 crown vic steering wheel, but, again, the horn stuff is the same. One of the horn contacts on the turn signal switch is making contact with one of the copper rings on the steering wheel, and the other horn contact touches the other ring. On the front of the steering wheel, with the three-legged horn button removed, you will see a little metal 'finger' sticking out. That is in contact with one of the copper rings on the back of the steering wheel on the back and is in contact with the metal ring on the three-legged horn button. You will also see two contacts, each made of white plastic with a little copper contact on the front of the steering wheel, held onto the wheel with a screw. In this picture of the back of the three-legged horn button I have circled two contacts on it. When you push on the horn button, that causes one, or both, of the contacts on the horn button to touch the contacts on the steering wheel, completing the circuit and causing the horns to honk.
It is a very common problem for the contacts on either the steering wheel or the horn button to be worn down enough to either make very poor contact or no contact at all. To get your horns to work, first check and see if the horns themselves work by removing one, grounding the mounting bracket on the negative battery post and supply power to the connector on the horn with a wire from the positive battery post. If the horns work, check with your volt meter to see if power is getting to the horn end of the wire that is supposed to be supplying power to the horn with the button pushed. If yes, then the horns aren't making good contact with the radiator core support because of excess paint or something. If no power is getting there with the horn button pushed, you'll need to remove the horn button by pressing and turning the horn button counter-clockwise and it will pop off of the steering wheel. Take a little wire or the trusty screwdriver or something and ground one of the contacts on the steering wheel to that little finger sticking out. If that makes the horns honk, the problem is the contacts on the back of the horn button. If no, then you have to remove the steering wheel. Once you've accomplished that, take the screwdriver and and ground one of the contacts on the turn signal switch to the other one and see if the horns honk. If yes, then the steering wheel was not making contact with the turn signal switch contacts and when you reinstall the steering wheel, you need to make sure that it gets pulled down far enough to make contact by checking to see if the horns honk by grounding one of the contacts on the front of the steering wheel to that little finger. If no, then the yellow wire probably isn't supplying power to the system at all and you need to first check if the yellow wire is bringing power from the headlight switch. If yes, you'll be needing a new turn signal switch.


Bruce404 said...

My son and I are the type of Mustang owners you mentioned in your blog. We bought the car for him to learn about automotive systems and to drive - not show!

We have a '68 with a horn related problem - maybe you can help. We found that when the steering wheel is not installed, the steering column shaft 'floats' electrically (not grounded) and that when the steering wheel is installed the shaft is at 12V. That would all be fine except when the wheel is turned to the left, the shaft grounds electrically to something in the steering box - or elsewhere and shorts out everything!

Should the whole steering wheel and column be at +12V? That seems wrong - and maybe dangerous. We are wondering of our steering wheel is defective.

Any ideas? Thanks for any help.

Veronica said...
This comment has been removed by the author.
Veronica said...

You are correct on both counts. It is both wrong and dangerous. Power for the horns comes to the horn button by way of the yellow wire, to the ouboard contact,through the horn button and out to the horns by way of the blue wire with the yellow stripe. It should not be grounding out on the steering column. This sounds like a problem with the steering wheel itself, but, to check that hypothosis out, remove the steering wheel, and run a jumper from one of the horn posts on the turn signal switch straight over to the other horn post. If everything works like it's supposed to, then the problem is definitely in the steering wheel. If everything blows again, then the problem is probably that the blue/yellow wire has a bald spot somewhere and is shorting itself out on the steering column. If the steering column is showing 12V with the steering wheel off and with the key in the off position, the problem will probably be with the yellow wire bringing power to the horn button. That wire has power on it all the time.

The cars that I am most familiar with are the 65/66 cars, but, the horns of 68 work in exactly the same way. However, you have the added variable of the emergency flasher switch also being on the steering column, whereas, on a 65/66 car, that switch is over on the passenger side of the car. Really makes a lot of sense to put it over there, but, that was how they did it. The point of this being that the emergency flashers also have constant power, so, it's possiblr that the emergency flashers are contributing to yourproblem, also. I would really be surprised if they were, but, it's possible.

Veronica said...

I deleted my first response to this because I tried typing it without having my glasses on. That didn't work out very well at all. It looked like some strange foreign language.

Bruce404 said...

Thanks for confirming my suspicions. After some additional investigation with an ohm meter, we disassembled the steering wheel and found where the outer contact ring was out-of-place. We reassembed and re-checked the steering wheel, cleaned the turn signal switch (for good measure) and added some grease. It works perfectly! [My smart, fast, strong, kind, and good-looking 16-year old son is now as invincible as ever.]

It is bad enough for the 41-year old parts to create problems, but in a way worse for the after-market stuff (new steering wheel) to be wrong. Thanks, again.

Veronica said...

It really is pretty sad when brand new stuff is the source of the problems, but, that is frequently the case. Glad you got it all sorted out.

Lurch said...

Thanks for the very informative posts. My horn was working intermittantly before it stopped working altogether. After reading your posts, I went out to the garage, pushed on the wheel really hard and then pushed the horn button, it worked! So, I decided to simply tighten the wheel nut, which was loose. The contacts seem to be back in contact and the horn works perfectly everytime.

Thanks again
Lee Horton
67 Mustang Cpe 200

MustangMikey said...

Veronica, thankyou for your site and your advice. I also have a horn related mystery on my 66 mustang. All I get is a burp from the horns like they are trying to make noise but can't. I have jumped the hors to the battery and they are working fine. I have removed the steering wheel and jumped accross the contacts, and get a small spark and a burp. It appears that I could have a problem with current supply. I noticed the power for the horn comes from a connection on the light switch and not from a direct connection to the fuse block. Could I be looking at a faulty light switch?

Veronica said...

That is one possibility. The first thing that I would do is unplug the turn signal switch at the base of the steering column and jump the yellow wire that supplies power to the horns over to the blue wire with the yellow stripe that goes out to the horns on the connector that is part of the underdash harness, by-passing the turn signal switch. If the horns work like that, the problem is the turn signal switch. If not, I would jump a known good power source over to the blue/yellow wire. If that doesn't work either, the problem is somewhere along the blue/yellow wire. If it does work like that, then the problem is somewhere along the yellow wire that supplies power to the horns, which could very well be the headlight switch, or possibly the connector that plugs into the headlight switch.

Beavis said...

Thanks for the great article and especially for the picture. I am finishing a restoration of my first car, a 66 coupe, for my son to drive. The horn was always flaky when I drove it 20 years ago. I bought a new contact kit and no matter what I do the horn is always on (honking). I don't know at this point if I have the 4 pieces of the horn ring installed correctly I have tried so many iterations. Can you tell me the order and facing direction of the horn ring pieces? Also, does the little flat metal hook at the top of the wheel touch the back of the contact plate or ride along the edge of the plate? Thanks!

Veronica said...

Sorry this took so long. I just got back from vacation monday and had a whole bunch of stuff to get caught up on. I'll take a horn ring apartin the morning and put the pictures up. Iy kind of sounds like either the big spring behind the horn ring isn't doing what it's supposed to or maybe one of the new contacts on the steering wheel isn't seated correctly. I'm pretty sure that the hook thingy rides the edge, but, I'll double check that, also.

Chris said...

Veronica, just wanted to say thanks. I bought my 68 about a year ago and passed inspection once without a horn but didn't this time. This is my first real issue with the car and thanks to you I was able to figure out that my turn signal switch needs replacing. Thanks again!

Scott said...

I'm having the same problem as MustangMikey..

Any ideas what would cause the horns to just make a burping sound when closing the steering wheel contacts?

When I disconnect the harness and short across the Yellow and Blue-Yellow wires, the horns work great.

Veronica said...

What that tells you, Scott, is that the problem lies somewhere in the stuff that you by-passed. The next thing to do is to plug the turn signal switch back in, remove the steering wheel and do the same by-pass on the two contacts circled in the last picture. You can just use a screwdriver or something and lay it down across the two contacts. If that also works fine, then the problem is probably wear on the contacts on the back side of the horn button. If grounding the two contacts on the turn signal switch does not make the horns blow the same way that by-passing the switch entirely did, then it's time for a new turn signal switch.

Daniel said...

I am having a horn related problem on my '66 mustang. i replace the steering wheel about two years ago and i remember that i had a problem getting the horn to only make noise when i pushed the button(it was always honking). i figured that out, but a few days ago i was driving and my car started honking when i turn. i took the horn button off and it still honks when i turn. I unplugged the left horn because that is the only one that works, and when i pressed the horn the right horn would burp, but when i turned the right horn would honk without me pressing a the button. today i decided to take the whole steering wheel off to try to fix the problem, and i notice that one of the copper contacts on the steering column is bent and worn off on the top and there are copper shaving all over the place. i tried to bend it back into place but it wont bend. i decided to put the wheel back on and then i realized that the horn stopped working all together even when i turn. im thinking the copper contact must be the problem so i looked in my NPD magazine for a replacement but i cant find anything. do you know where i might find it or what it's called? also my steering wheel seems to rub on something which makes it hard to turn at times. am i over tightening the nut in the middle?

Veronica said...

The contact is part of the turn signal switch, and is not something that can be replaced all by itself. You'll need to replace the turn signal switch. And, based on what you've said, that is indeed what you need to do for all of those various ailments your horns are experiencing. And, yes, it is possible to pull the steering wheel down so far that it is scraping on the steering column tube, causing some drag and to make some funny scraping noises. There are a couple of ways to go about fixing that. You can either not pull the steering wheel down quite so far you install it, as long as that isn't leaving that nut loose enough to back itself off over time, or, you could loosen the strap that holds the tube to the dash and move the column a hair closer the steering gear box.

Hazzea said...

Thanks for very useful information and a nice blog!

I recently replaced my steering wheel as well as the horn signal ring.

When I couldn't get the horns working I disconnected the main plug from the steering wheel and measured the voltage of the yellow cable from the light switch. It's only about 0,6 V... How come?

While having the main plug disconnected, I also checked the resistance between the yellow cable and the blue cable with yellow stripes when honking the horn, and found that the setup works. So from that perspective maybe there aren't any problems with the turn signal switch and the steering wheel/horn signal ring setup...?

Veronica said...

I think that I would start by unplugging the turn signal switch and checking to see if I had 12V at the yellow wire in the connector that the turn signal switch plugs into. If there isn't 12V there, then the turn signal switch and steering wheel are not the problem. If you do have 12V there, I would run a jumper from the yellow wire over to the blue/yellow wire in that same connector. If the horns work like that, then the problem is with either the turn signal switch or the steering wheel.

Hazzea said...

After flickering a little with the yellow wire I actually got 12V so the light switch and the steering wheel/horn signal ring is ok.

I forgot to tell that my car (1965 V8) is equiped with a horn relay.
I can't find a wire diagram for horn relay 65:s. Is it the same blue-yellow wire that powers the horn relay too?

Veronica said...

Actually, the cars that came with the horn relay also came with a generator and are wired differently from the other, later cars. How your car should be wired, if it did come with a generator instead of an alternator, is that there is a yellow wire coming from the voltage regulator supplying power to the horn relay and a blue/yellow wire that goes to the horn button. When you press the horn button, that creates the ground and the horn relay sends the power to the horns through two yellow/green wires. This is for the cars that are considered to be 64 1/2s. If you could tell me the scheduled production date of your car, that would really help out. Then I would know how your car is supposed to be wired up. The 64 1/2s look like the 65s, but, are wired completely different in a lot of ways. Your car might still be wired like a 64 1/2, or, it could be wired like a 65, or possibly, some kind of hybrid of the two. On my car, for example, which is a 64 1/2, I have the two big 64 1/2 horns mounted down on the strut rod brackets, but, I have them wired like a 65, without the relay.

Hazzea said...


Well actually I'm not sure if my car's VIN number is trustworthy...

Here's the VIN number:

and here's the other info from the data plate:

76 A 26 26D 72 6 5

The data plate on the door looks completely new and its VIN number matches the number stamped in the engine room under the hood.

What I can see the number says that the car should have a 200 6 cylinder engine and be raven black.

The interior matches the door number, as well as the transmission (it's a 4 speed manual), but I can't find any traces of raven black colour (at the moment the car has a non-original colour).

When I recently bought it, it featured a V8 289 engine with alternator. The old dash, which I've replaced, had an alternator lamp, and the steering wheel assembly definately has two wires (one yellow and one blue-yellow).
My heater is also the three-speed version, and the spare wheel setup in the trunk is also the one of a 65.

But the horns are mounted on the strut rod brackets, powered by two yellow-green wires from the relay (mounted below the voltage regulator). From what I've found out the horns are aslo the 66's version, not the 65's (and definately not the big ones of the 64 1/2:s)

So could it be a hybrid...?

Best regards,

Veronica said...

Most often, these cars become a hybrid of sorts over time because of people replacing components that fail with components that they already have on hand, or components that, for some reason or another, are easier to get. Your car does seem to be a collection of stuff spanning two year models. It could be that whoever did the swap from 6 cylinder to V8 also sorted out some electrical weirdness the car had by pulling electrical components off of the donor car that they used for the motor, suspension, steering, transmission, and rear end. If your turn signal switch has the 6-wire and two wire connectors, that is definitely the 65/66 style turn signal switch. Since your car is not supposed to have the horn relay anyway, the way to proceed might be to check and see if the blue/yellow wire actually has power on it when the horn button is pushed, and does not when the horn button is not pushed, find where that wire comes through the firewall from under the hood, and run new wiring from there straight to the horns.

Dave BARNES said...

HI Veronica, Is it possible to splice in a relay between the fuse block and the turn indicator switch plug at the base of the steering colum. I have a grant wheel on the car I bought and I don't like the hot wire on the horn contacts always sparking.

Dave B Melbourne Australia.

Veronica said...

The horn circuit does not go through the fuse box. The yellow wire that supplies power to the horn button comes straight from the headlight switch, which has an internal circuit breaker. It would not be difficult to run that through a relay, though. If you snatch the instrument cluster out, so that you have easy access to the headlight switch, you will (should) have a yellow wire coming out of the connector that's plugged into the headlight switch. That is the wire that supplies power to the horn button. It is hot all of the time, and doesn't do anything other than supply power to the horns. It could just as easily supply power to a relay without effecting anything else.

Veronica said...

I just noticed that you have a picture of what appears to be a 70 model car as an avatar. If what you actually have is indeed a 70 model car, it's still a yellow wire coming out of the headlight switch connector, but, you don't have to pull the instrument cluster to get the headlight switch down to where you can reach the wires. You can just stick your hand under the dash, feel around for the switch, depress the knob release button, which should be over on the passenger side of the switch, pull the knob/shaft thingy out, unscrew the bezel retainer, and pull the switch down to where you can reach the wires.

Robert Kresler said...

I have a 66 stang with an alternator. The horn does not work. I went through all your very informative posts and can't seem to find an answer to my problem. When I remove the steering wheel and jump across the two copper posts, the horn works. Using a test light, there is constant power to the inner most post. When the steering wheel is installed however, that power is lost, ie the test light goes out. I have continuity from one side of the steering wheel ring to the other side and the copper post is engerized and is making good contact with the steering wheel ring. However, it seems that when the wheel is installed, it grounds itself to the steering coloumn shaft. Is this correct? It looks to me as though the inner ring, which is always energized on the steering wheel is mounted to the metal center on the steering wheel and hence grounding itself to the steering coloumn shaft when it is intalled. I sure hope I am making myself clear. What gives??

Veronica said...

If the contact that brings constant power to the horn button stuff was actually grounding itself out on the steering column that would become immediately obvious because that would cause all sorts of problems involving melting wires and smoke. I think that the first thing that would check would be to see if I had power on the the two contacts on the steering wheel that the three-legged horn button hits when pressed. It could be that there is an alignment issue on the two posts for the horns on the turn signal switch, or it could be that the ground tab on the steering wheel itself isn't making contact, but, I would definitely start by checking those two contacts on the steering wheel.