Horn wiring repair

[busdaddy]

You have to attach it to the tube somewhere, I guess you could take the long route back up through the nose and out under the speedo to the column, but a small grommet in the floor just forward of the cover plate and a screw or pop rivet to the front of the tube is easy and mostly hidden.
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[MikeSoCal]

Thank you Busdaddy. The steering wheel is new and the steering column was painted and perfect so that is the reason I didn't want to remove it. I ended up soldering a wire to one of the existing holes on the bottom of the column, pushed it down in the tube out of sight, through the wire holder and connected the two. Worked like a charm and no drilling or screws. Horn works and no trace of anything done.
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Restoring a 1971 VW Westfalia

[Ben Middleton]

I've done all this work but the horn isn't working. It's not making a circuit between the brown wire and the wire on the column tube when I press the horn button.

Where should the steering wheel actually connect to the column tube so the circuit can be completed? My column tube seems to be completely isolated from the steering wheel; which would explain why it doesn't make a circuit once the button is pressed.

[SGKent]

Ben, pull the wires off the horn and check them for voltage. One wire should have 12V to it and the other not. Hook the 12V wire up to the horn, ground the other terminal and make sure the horn blows. Once you have done that, follow the other wire, including your repair to the horn ring and make sure that when you ground it the horn blows. Once you are sure that all works, we can track down where the rest of the circuit is failing. What year is your bus? It isn't in your sig line or avatar.
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[Ben Middleton]

Thanks for your help. It's a '72 crossover. I'll do those tests now and get right back to you

[SGKent]

your horn, stop lights, and brake warning light are all on fuse 12. If the horn lacks 12V check that fuse. If the horn has 12V and doesn't honk when the other terminal is grounded, then replace it. Often nothing is wrong with the system other than a bad horn. Some have an adjustment screw that can be turned to get it to work better. Over time the vibrator points inside it wear.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Ben Middleton]

I haven't got 12v at the horn so I connected an auxillary battery to test it instead. I must have a damaged 12v wire to the fuse so I'll sort that out later.

The horn was blowing permanently once I connected the auxillary battery, without me pressing the button.

Using a multimeter, it shows there is currently continuity between the steering wheel and the ground wire, when it is not being pressed. To eliminate the horn ring, I removed the ground wire and tested it against the steering column. There is continuity. For reference, I attached my ground wire to the bottom bolt of the two which attach the coupler to the steering box.

On the Bentley diagram, I am missing seal 13. Any idea what this is for? Is it critical to isolating the ground circuit?

[SGKent]

My understanding is that on the 68 - early 74 system if the column is grounded then the system doesn't work right. Here is a post from TCash that may help. You need all the insulators in place is my understanding.

[Ben Middleton]

Thanks for that. I think I've followed that exactly but I still don't understand how the column tube becomes grounded once the horn button is pressed.

Where does the column tube connect to the steering wheel?

[kreemoweet]

[SGKent]

Edited:

Someone correct me if I am wrong please. My understanding is this is the electrical path 68 - 74. (75-79 is different.)

The steering column has a shaft and a housing. The shaft is hollow and has a wire in it. All housing insulators must be in place on the housing so it is electrically isolated from the bus chassis.

12V+ goes to one side of the horn from fuse 12.

The other side of the horn goes into the wiring harness and comes out at the base of the steering column housing where it connects to a tab.

The electrical path is from the tab, up the isolated housing to the top.

At the top the spring and ring on the button and associated parts connect the path to brown wire in the center of the shaft when the button is pushed.

The path then goes down that center wire to one of the bolts on the flexible puck ON THE STEERING BOX SIDE ON 68-74. (On 75-79 that is different.)

The steering box is connected to the chassis and chassis ground by its bolts. Circuit complete.

The hard part to grasp is that the column is isolated from the bus. Pushing the horn button connects the column the brown central wire so the return path is thru the brown wire in the shaft to ground via the steering gear side of the steering puck. When the button is pushed, the column will read a ground but when the button is at rest then the column is 12v+ because it is on the horn side of the button switch.

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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Ben Middleton]

Thank you for your help guys. I've now confirmed that the horn button does work (but only once I've removed the steering unit from the support bracket). This means that the steering column is being earthed through the support bracket.

I don't have any of the 'plastic coated washers' on my support bracket. Are these necessary to isolate the support bracket from the ignition housing?

I was under the impression that the plastic piece that goes between the column tube and the ignition housing was designed to isolate the housing from the tube. Should I assume that I have fitted this incorrectly?

Thanks again

[kreemoweet]

The column tube shouldn't be touching the ignition housing with or without the plastic sleeve. The large rubber bushing that holds the tube in the housing should be holding it centered without touching anything else. My understanding was that the plastic sleeve was for preventing the lock bolt from dragging on the tube. For what exact reason, I do not know (I don't have those parts on my bus), but I suppose the cutting-off of the power to the ignition circuit is not perfectly syncronized with the extension of the (grounded) lock bolt, so that the unwanted sounding of the horn could sometimes occur when the bolt hits the (energized by the ignition circuit) steering tube.

The ignition housing is grounded when installed. That's why it has that little plastic ring around the top of it, so the (normally energized) turn signal switch housing won't touch it and thereby sound the horn.
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[Ben Middleton]

Thanks for that info - it helps a lot.

Hmm, why do you think the steering column is becoming grounded once I attach the ignition housing to the support bracket?

The large rubber bushing was slightly damaged when I put it back on but, because it isn't available to buy, I had to reuse it. Although it still provided a complete seal, with only a small section at the top slightly cut away.

There also never seems to be any continuity between the steering column and column tube, even with the button pressed down. Very confusing.

[Ben Middleton]

Sorry for the double post!

Just checked and the steering column is becoming grounded via the support bracket once I remove the key and steering lock pin goes into the hole in the column tube.

So it's touching something it shouldn't be?

[Amskeptic]

[kreemoweet]

[Ben Middleton]

Ah of course. It's only relevant when the key is in the ignition. Thanks guys.

Pretty sure the circlip and washer aren't touching the column tube but I'll double check.

I believe it has the wrong bearing in it. The later one, 74-79. Is this the issue?

[kreemoweet]

[mikewire]

I have a '72 and had to fix my horn circuit properly, so I have some practical experience here. I can confirm, it's kind of a pain in the arse.

Did I read earlier you are missing #13 in this diagram? If so, I believe that would cause a problem. I might have to run to my garage to confirm, but...without that plastic/rubber isolating seal, the steering column housing would not be isolated, and the horn would sound the instant the key is turned to ON (not start).

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1972 VW Kombi 9 Passenger Deluxe w/ 2.0L F.I. VWAC swap
1965 VW Beetle Deluxe Bahama Blue