Getting the Horns working properly

[sputnick60]

This is an attempt to guide the ones who are having trouble with what is really a simple circuit. The confusion I think is most people don't truly understand the symbols in the circuit diagrams. Understandably so, because this portion has the most cryptic symbols of all. Even though all is shown in the diagram this horn arrangement, especially the parts associated with the steering wheel are not easy to follow. I'm an engineer and I too needed a good look at it to get the hidden message. SO, we won't use the circuit diagram and instead have a thoroughly proper look all the parts and how they go together to make this work.

Firstly I will assume all the parts you have are are not faulty. That the horns ( or claxons ) do make a good noise when volts are applied and the relay will similarly activate.

Hmmm.... Maybe better not assume, lets check those as well.......

Step 1: Check the Horns can make noise:
Get some 2.5mm sq. wire. A metre will do. Crimp a spade connector to each end and cut it in half to make two half meter lengths and then strip 2 or 3 cm. from the non crimped end . (Later you will keep these in your stash of useful tools. )

Test each horn ( hoch & teif ) by connecting the spade ends of each wire to one or the other of the horn's terminals. Then, with a good battery up on the bench, (or on your knees around the back of the car) hold the stripped ends on the respective battery terminals. You might need some hearing protection because if the battery is truly good and so too are the horns, then it'll be loud. If you hear nothing, check your connections and try again or read the horn refurbishment thread.

A wall wart, battery charger or most power supplies won't provide enough current to drive the horns. A battery will. So use a battery.

Step 2: Check the Relay works.
The job of the relay is to separate the high current part of the circuit from the low current control part of the circuit. It has four terminals. Two are for the coil and are stamped 85 and 86. The other two are for the high current capacity contacts and are marked 30 and 87. You can do a basic check of an un-engergised relay and measure the d.c resistance of the coil and conductivity across the contacts. With a multimeter set to the Ohms range connect the test leads to terminal 85 and 86. If it reads anything less than open circuit the coil is probably OK.

This shows a 12 volt relay has some 80 ohms across the coil. Yours could read something else but an open circuit suggests the test leads aren't on properly or the coil has burned out and thus the relay is a dud... or you are just clumsy. Using ohms law we can work out this particular relay would consume 1.8 watts of power

This shows a 6 volt relay has about 3 ohms. Read the earlier comment about interpreting this result. Ohms law tells us this particular relay would consume 11.6 watts

To test the relay properly, you should get it on the bench with a battery and your test leads.
Connect those test leads to terminal 85 and 86 and a multimeter set to Ohms connected to terminal 30 and 87. I used alligator clips on the meter's leads to solidly hold the connection. Alligator clips are cheap and can save damage from slip ups. The relay unenergised like this should have the multimeter reading an open circuit. When you connect terminal 85 to the negative and terminal 86 to positive on the battery, you will simultaneously hear the relay "Click" and see the multimeter reading a low value of fractions of Ohms. If it does that, the relay is probably OK. This test doesn't prove the relay can draw heavy current but unless the relay has been abused, this level of testing sufficiently proves function. We will test for heavy current later in Step 5.

Step 3: Verify the wiring on the relay.
The horn relay clips onto a hole in the inner guard near the spare tyre on the LHS of the car. It is wired thus.
Bundled in the loom on the LHS of the trunk and starting at the first fuse is a 2.5mm sq. red wire to terminal 30. This is the heavy current feeder that is switched to the horns. It also provides power for the relay coil when it gets energised. That is achieved with a 1.5mm sq. wire jumper joining terminal 30 to terminal 86 to provide the power to the low current control path.
At terminal 87 a pair of 1.5mm sq. black wires go down to the horns. This is the switched heavy current path that will drive the horns.
At terminal 85 is the brown 1.5mm sq. switching wire. When this gets connected to ground via the steering wheel, the relay energises and the horns sound.
The relay's canister is not connected to the electrical circuit so don't bother trying to get a connection to the body there.

Step 4: Verify the Horns are mounted properly.
The black pair of wires from terminal 87 that run down to the horns are connected to a terminal on each of the horns. It doesn't matter which one because the horns don't care about polarity. But don't put the black wires both on the same horn and don't hook them up in series either. They are meant to be wired in parallel. The brown 1.5mm sq. wire is made in a "Y" lead with a ringlet and two spade connectors. The spade connectors go to the remaining terminal on the horn and the ringlet is used as a washer on the mounting stud of one of the horns. The mounting stud on the horn serves no electrical connection inside the horn and the brown wire simply extends the earth derived at the mounting brackets to the horn's terminals.

Step 5: Preliminary testing of the High current circuit.
If everything is correct you can sound the horns by energising the relay. You don't need to use the horn button to do that. Instead, just provide a ground at Terminal 85 on the relay (the one with the brown wire). To do that take a length of test wire say 1.5 mm square. Strip a centimetre of insulation then hold one end on a good earth point like the bolts holding the fuel tank in place. Take the other end and carefully touch Terminal 85. The relay should energise and the horns should sound. Be careful to keep this test ground away from the other relay terminals. You will blow a fuse if terminal 30, 86 or 87 are grounded even for a split second. If this test fails and all the previous tests worked out, then I'd say the relay is a dud and can't carry the current. Either that, or you've just discovered yourself more suited to mechanical rather than electrical work.

Step 6: Checking the Steering column is set up right.
This section causes the most headaches. I'm going to describe the set up for a '66 Ghia with which I am the most familiar. It should be the same for at least '61 through to '70 model years.

I invite others with the knowledge of the steering column arrangement for later and earlier model years to add those details. Please!

The steering system uses an outer tube or column to support an internal steering shaft. The column is not connected electrically to earth and so can be used as a switching device to activate the horn relay. Much confusion exists about how this is all hooked up but its function is really simple. Namely, it provides a ground connection for terminal 85 on the horn relay when the driver presses a button in the centre of the wheel.

So, first check the column is mounted correctly. At the firewall the column is supported with a rubber insulator shown in the picture below. The outer column must not touch the inner shaft throughout the rotation of the steering wheel, if otherwise the circuit may find a ground connection and cause random horn soundings when steering around corners. The steering shaft must be straight. This is not usually a problem for the early single piece shafts but later shafts made with a safety collapsible/shear section may have become slightly curved and cause the issue. The shaft might need straightening but exercise caution around the structural integrity of this safety feature. Get a good replacement if required. The position of the steering box also has influence on the shaft centreline within the column. You might have to loosen the steering box to reposition it to the optimal position. This will further require a re-centring of the steering mechanism. Be careful with the steering mechanism, your safety depends on it. Also marked on the picture is the other end of the brown wire from terminal 85. It must go on the small spade lug at the end of the column. Make sure there is no dirt or paint that would prevent a connection.

Underneath the dash is a rubber pad that stops the column rubbing thorough the paint and inadvertently making an unwanted connection.

The top of the column is held with a bracket that envelops a rubber ring. The bracket squeezes the rubber which grips the column and maintains electrical isolation to earth. I don't have a better picture of this but trust me, it is insulated in there.

The steering wheel bearing sits in the top of the steering column. The bearing is just a pair of inverted pressed steel rings holding a race of ball bearings. The only special feature to consider here is the grease in the bearing. It is a conductive grease that ensures the steering shaft is electrically connected to the steering column throughout its rotation. If you have "refurbished" this bearing, you should have used conductive grease. You can get some of this grease from RS Components or Farnell on the web. It is a specialised thing so buying a new steering wheel bearing is probably easier & cheaper. Remember, always, unless made of "unobtainium", OEM is best.

The steering shaft is inserted through this bearing and through the column. At the bottom of the steering shaft is a rubber coupler compensating for alignment differences between the steering box and the shaft and somewhat reduces vibration transmitted up the wheel. Because it is rubber, this coupler also insulates the steering shaft and column from ground. However, in recent times suppliers have been providing rubber couplers of a new material that, although appearing identical to rubber and is mechanically a good fit, it is electrically conductive! If this type of coupler is introduced the horns will permanently sound. So we have yet another test to perform.

With a multimeter set to the Ohms range Connect to the bushings on the Coupler and check there is high resistance between each of the bushings.
Here is a photo from user bnam showing a coupler that fails the test. 1.2kΩ shown below is not high enough and in some instances will allow enough current to pull in the horn relay. If you have such a coupler it should be rejected and another sought for use in its place.

The horn switching occurs at the top of the column and since it is all insulated from the rest of the car a ground connection must be provided by some means. A ground wire is run inside the steering shaft and terminated at a lug on one of the washers bolted to the steering box at the rubber coupler. It is important that the lug is on one of the bolts attaching the steering box to the coupler. If it the lug was connected to one of the steering shaft bolts, there would be no ground connection provided on the brown wire. This is a common error.

You should use the multimeter set to the Ohms range to check the steering box does indeed provide a ground at the coupler bolt. Put one lead on the bolt and one lead on a known good chassis ground. The multimeter should read a low value of fractions of ohms. This ground could be broken because of paint or grease creating unwanted insulation at the steering box. This is a rare fault but it has occurred, usually to pristinely painted trailer queens I suspect.

So the electrical connection from terminal 85 is extended to the column but has no path to ground . The ground connection is derived from the steering box and fed on a brown wire through the centre of the steering shaft to the top of the column where it can be switched with the horn button.


Part Seven: The Horn Button.
The horn button is a stack of springs, insulated washers and contact rings. It is best show in photographs
Below is a view of the Horn ring, contact ring, insulated washer and machine screw in the correct order.

This is the same thing but from the under side with the spring added.

And the view before it is all screwed in to the steering wheel

Finally we see the Horn ring, contact ring, insulated washer, spring and machine screws in place on the steering wheel with the wire attached to its terminal on the horn ring.

So now we have toured the horn system we can show a diagram with all the elements and how they interact.
This diagram shows the whole catastrophe as it is wired up and without the horn button pressed. Note the horn relay is relaxed and the horn contact ring shows a gap in the steering wheel.

The second diagram shows the button pressed and there is no gap at the contact ring. The horn relay contact is closed

The final diagram shows the electricity flow from the fusebox , through the relay where it splits to a) the steering column in the low current path, and b) the high current path to the horns themselves

So that should cover the whole mysterious horn system on the Karmann.

Go sound your klaxons!

Nicholas

PS I've edited this to fix up a bit of the grammar, add some extra things to check and fix up a mislabeled picture.
Further comment: over on the Beetle forum there is a similar thread that might help with its perspective....
https://www.thesamba.com/vw/forum/viewtopic.php?t=369613
[edit AUG2020: added section about testing for conductive steering couplers.
_________________
'66 Karmann Ghia Cabriolet...
'65 Porsche 356C Coupe...
2005 Mecedes Benz C180 Kompressor Estate
Stop dead photo links! Post your photos to The Samba Gallery!

[John Moxon]

Thanks Nicholas...great write-up. Added to the "How To" sticky.
_________________
John.
Judson Supercharger Information on The Samba
My 1958 Shorrock Supercharged Karmann Ghia
Stop dead photo links! Post your photos to The Samba Gallery!

[djway3474]

I think I just went to horn tech school. Thank you this is very useful. Now my brain just needs to remember "Check the stickies"

Great job!

[boinkffd]

Very very very helpful. Thank you.

[KGCoupe]

Thanks, sputnick60 - what a great How-To!

Now, can you offer any tips on how we can make every single part of our cars as clean and shiny as yours?
Talk about immaculate - Wow!

[O2COOLED]

Really appreciate this Nicholas. Great timing as I am having horn issues and this will go a long way in solving my problem.
_________________
"Sometimes people forget they signed up to a HELP & SHARE Forum not a pissing contest"

"At my age time is too short to respond to people with short minds"

Current: '69 Ghia Coupe
VW History:'63 Bug;'70 Bug;'73 412;'83 Rabbit;'86 Golf;'76 Fat Chick; 67 Ghia Coupe; '70 Bug

[sputnick60]

[sputnick60]

A few extra comments I thought I should add

6 volt cars are wired up the same as 12 volt cars. So where I've spoken about 12 volts you can substitute 6 volts. The tests, configuration and terminals are all the same.

Cars after '66 model years are 12 volt ex factory. Using double the voltage means a quarter of the current for the same power used.

Less current means thinner wires can be used. Thinner wires are cheaper. so 12 volt ex factory cars have lighter gauge wire wherever possible.

I have discussed how it is on my Ghia which is a 6 volt ex factory car converted to 12 volts with a new wiring harness built to the 6 volt specification.

So don't be concerned if your 12 volt car has lighter gauge wires in places I describe, so long as they match the sizes shown in the wiring diagram. (That's what those small numbers shown near each wire is trying to communicate)

This is a minor detail in the context of this post but it is best to be clear and put the whole lot in the mix while teaching/learning all this.

While browsing the Gallery I spotted this rather useful diagram and thought to copy it into this thread.

[Mod Edit] linking another thread from the Beetle 58-67 forum about the horn button assembly peculiar for a 60-61 model. Usually Ghias follow along with Beetle model years for core items and '60 is a peculiar model year for the horn button and steering wheel
https://www.thesamba.com/vw/forum/viewtopic.php?t=369613


Nicholas
_________________
'66 Karmann Ghia Cabriolet...
'65 Porsche 356C Coupe...
2005 Mecedes Benz C180 Kompressor Estate
Stop dead photo links! Post your photos to The Samba Gallery!

[vwcomet]

THANK YOU, THANK YOU, THANK YOU! My horn is FINALLY fixed! I followed your excellent guide and fixed my horn. My problem was the brown wire on the steering coupler. I had it connected to the shaft lug with a braided wire going around to the steering box lug and my horn would always be on. I moved the brown wire directly to the steering box lug, eliminating the braided wire and now it works properly. Such a simple thing. Thanks again.

[sputnick60]

[vwcomet]

OK. I will reinstall it. By the way, I followed the factory wiring diagram when I restored this car and the horn only gets power when the ignition switch is to the ON position. It seems as if it should always have power. Is yours the same way?

[sputnick60]

[KGCoupe]

[O2COOLED]

I am still having horn issues that just recently materialized. Everything works like it should when stationary but when I turn the steering wheel the horn sounds without my pressing the horn button. I went through the wiring in the steering wheel and everything looks ok. Obviously it's grounding out somewhere as it turns but where? I am planning to go under the gas tank and check out the wiring there but thought I'd check first if you have any tips on what to watch out for. BTW, I replaced the stock steering wheel with a Dino Luisi wood steering wheel.
_________________
"Sometimes people forget they signed up to a HELP & SHARE Forum not a pissing contest"

"At my age time is too short to respond to people with short minds"

Current: '69 Ghia Coupe
VW History:'63 Bug;'70 Bug;'73 412;'83 Rabbit;'86 Golf;'76 Fat Chick; 67 Ghia Coupe; '70 Bug

[c21darrel]

check the steering column and tube where it exits under the gas tank. Sometimes if it isnt centered, when turning it will ground out right at column where it goes thru exit tube. Sputnick's below is centered well.

[O2COOLED]

Thanks c21darrel. Jet lag and horn issues kept me up last night so I just went back to the garage and went over the whole set up. Figured it out! It was the turn signal cancelling ring. Somehow it was grounding when I turn the wheel. Tried switching to the old ring but still grounding so I just took it out and no more unexpected horn blasts! I'll have to just cancel the turn signal manually until I figure out a solution.
_________________
"Sometimes people forget they signed up to a HELP & SHARE Forum not a pissing contest"

"At my age time is too short to respond to people with short minds"

Current: '69 Ghia Coupe
VW History:'63 Bug;'70 Bug;'73 412;'83 Rabbit;'86 Golf;'76 Fat Chick; 67 Ghia Coupe; '70 Bug

[sputnick60]

There should be a gap of about 3 or 4mm between the wheel and the cancelling ring. Try loosening the screw in the cancelling ring and push it a fraction further down the column.

Nicholas
_________________
'66 Karmann Ghia Cabriolet...
'65 Porsche 356C Coupe...
2005 Mecedes Benz C180 Kompressor Estate
Stop dead photo links! Post your photos to The Samba Gallery!

[djway3474]

The crush column under the tank is easy to bend and make the column move all whonky. that could give it an elliptical movement and make the ring contact intermittently.

[O2COOLED]

Thanks all for the tips. Sputnick: The Luisi steering wheel does not really give me room to adjust the ring further into the wheel. Djway: I don't think it would be the column as I did not have the problem when I had the original steering wheel on. One thing I will try though is get new screws for the ring as the ones I used were pan heads and they may be rubbing as I turn the wheel. I could not use the original screws as the new wheel had a bit larger holes.
_________________
"Sometimes people forget they signed up to a HELP & SHARE Forum not a pissing contest"

"At my age time is too short to respond to people with short minds"

Current: '69 Ghia Coupe
VW History:'63 Bug;'70 Bug;'73 412;'83 Rabbit;'86 Golf;'76 Fat Chick; 67 Ghia Coupe; '70 Bug

[pierrox]

Great thread with a lot of info.

It confirms something I found weird on my car. But now I know it is a kind of design flaw from VW, not an anarchic rewiring on my car: the horn ring is a live 12v. And since it's made of metal, you can feel the voltage (I wouldn't go as far as saying electrical shock) if you touch a ground in the car at the same time as you honk - the paint below the gear shift knob is gone on mine, great grounding.

I took my voltmeter out, and indeed, there is 12V arriving at the horn ring all the time. It would have made sense to connect that wire to the brass ring just below the horn ring, making that one separated from the electrical circuit.