The Beetle/Ghia Horn SystemBy: Bob Ellis
The vintage VW horn system, as simple as it may be, gives many owners problems while trying to either diagnose a problem, or when reconstructing a horn system that has been cobbled/modified from the original system. The trick to getting this important safety item working again is to first gain the understanding on how it works, and to know the changes that occurred over the years of production.
The VW horn is a simple diaphragm type that has 2 terminals on the back side. The two wires that attach to these terminals provide power and ground circuits to the horn. The horn is not polarity sensitive, so it doesn’t matter which wire goes to each side. Power to the horn is supplied directly from the fuse box via a black wire with a yellow stripe on the Beetle, and via a black wire on the Ghia from the relay (Ghia’s have dual horns, and require a relay). This side of the circuit really never changed over the years of production, making this side a no-brainer. You either have power to the horn, or you don’t. The ground side is where the fault usually lies, and also where the changes were made over the years.
Corrosion, water and dirt are the real enemies of any automotive electrical system, and the VW horn is no exception. Due to the horn’s location in the front fender of the Beetle and Bus, these two are much more susceptible to the elements. This is why VW supplied the horn wires with boots when the horn was moved from the front bumper on Beetles in the late 1940’s, and why the horns were mounted in a large boot in the Ghia’s nose. The real key to a good working/long lasting connection is protection. When doing repairs on wiring and terminals, always use die-electric grease on every connection! This keeps water out, and keeps that evil corrosion from forming. Use Horn wire boots on the horn connections, and smear some grease on the sealing surface of the boot while you’re there. Water will never enter again! As you work your way through the system, apply this wonderful stuff to every connection that you find. It will quickly become your friend.
Diagnostic procedures
1. First, check all of the fuses. Any that look questionable or burnt should be replaced before going any further.
2. Visually inspect the horn and any connections to the horn/s and relay (on the Ghia). If any look dirty or corroded, clean them with a small wire brush and apply grease. Are the boots in good shape?
3. Have a friend push the horn button while you are down by the horn armed with a 12 volt test light. Connect the alligator clip side to one terminal and touch the pointed end to the other. If the light illuminates, you have power and a good ground system to the horn. If the horn refuses to beep, the horn is toast. A secondary test for the horn can be made simply by connecting power to one terminal, and ground to the other...
4. If the light doesn’t come on, Attach the alligator clip to a good ground and touch the pointy end to the black/yellow wire. If the light doesn’t react, trace the power wire back to the fuse box and check both sides of the correct fuse for power with the test light. There should be power on either side, as this wiring gets supplied from constant battery power.
5. Once you’re sure you have power to the horn, and that the horn is good, the last thing is the ground circuit. This is where all the mystery lies.
Which system do you have?
Pre 60 Beetles and Ghia’s
On these models, the ground originates from a bolt on the steering box, is then jumped around the steering coupler with a braided copper strap to a screw terminal on the end of the outer column. This grounds the column.
When the horn button is depressed, the ground signal is transferred to the wire attached on the backside of the button. This wire travels halfway down the steering shaft, to a copper sleeve that is attached to (and insulated from) the steering shaft.
Attached with a clip, to the side of the column tube, is a spring loaded carbon brush that makes contact with the copper sleeve on the steering shaft, and transfers the ground signal to a wire attached to the end of the brush. This wire completes the circuit, as it runs thru the body to the horn (or relay on Ghias).
Problems associated with system are:
1) The carbon brush not making good contact with the copper sleeve. This can originate from either a corroded copper sleeve (This can be cleaned by wrapping a small strip of emery cloth over a pencil sized dowel, inserting it into the hole, and turning the steering wheel many times from lock to lock), a worn out carbon brush or it’s mounting clip.
2) A bad contact at the connection from the horn button to the wheel (clean the inner hub surface where the buttons outer spring contacts with the wheel).
60-67 Beetles and Ghia’s
On these models, the ground originates from the steering box side of the coupler. A wire attached to one of the 2 mounting bolts runs up the column and to a screw on the horn ring. When the ring is pushed, a contact ring makes contact with the column tube, which in turn grounds it. Attached to the bottom of the column tube there is a male stake-on terminal. A wire from this terminal travels to the horn (or relay on Ghias), thus completing the circuit.
Note) 61-62 Beetles and Ghia’s are slightly different. Instead of using a wire to transfer the ground signal up the steering shaft to the button/ring, the signal was transferred by the steering shaft itself. This meant that the column had to be insulated from the steering shaft. VW did this with an insulated bearing/sleeve (NLA). These years can be made operational by installing a 63-67 column, steering wheel, and horn button/ring.
68-70 Beetles and Ghia’s
On these models, due to safety regulations, the steering column had to be solidly bolted (and grounded) to the dash. This meant that the outer column tube could no longer be used as a route for the ground signal. To isolate the horn circuit, VW used a series of plastic insulating sleeves on the outside of the upper column bearing. The ground signal for these years travels from the steering box, up the steering shaft via a wire to the horn ring/button. When it is pressed, the signal travels thru the steering shaft to the bearing, and routed to the horn (or relay on Ghias) via a wire soldered to the bearing.
71-79 Beetles and 71-74 Ghia’s
Like the 68-70 models, the column through the last of the air-cooled models is grounded to the body. The signal is supplied by the (grounded) column, to a redesigned 2 piece contact ring mounted behind the steering wheel. When the horn button is pressed, the signal transfers from one half of the contact ring to the other. From this side of the ring, the signal passes through a wire to the horn (or relay on Ghias).
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