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PostPosted: Fri Jun 16, 2017 10:03 am 
356 Fan

Joined: Mon Sep 10, 2012 1:25 pm
Posts: 12
I'm all most there with reassembly of the electrical circuits on my 59' 356A coupe but have a problem with the horn connection. I have a solid 2 ohm resistance between the copper sleeve and the steering column. The flasher, lower band, is OK. I have taken it apart several times, cleaned everything, put a sleeve down the wire length inside the column, flossed the gap in the insulator under the copper band and nothing effects the 2 ohm reading. There is no resistance in between the copper strap and the wire terminal at the steering wheel end. I am not sure it worked when I bought the car ~20 years ago, or ever worked???
Any suggestions/ideas would be greatly appreciated. Fall back is to forget the flasher and use the lower band for the horn!
Carl


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PostPosted: Fri Jun 16, 2017 5:23 pm 
356 Fan

Joined: Fri Dec 03, 2010 7:42 am
Posts: 218
Can a photo help explain the objects that are making trouble? I don't understand where the resistance measurement is being made (from / to).


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PostPosted: Fri Jun 16, 2017 5:45 pm 
356 Fan

Joined: Mon Sep 10, 2012 1:25 pm
Posts: 12
Unfortunately I didn't take any photos before reassembling and temporarily moving on. There are two copper bands around the inner steering columns that the horn and headlight flasher connect to. There is then a wire for each that is brought up the center of the column and connects to the horn button and horn ring on the steering wheel. With everything disconnected, I am measuring the resistance from the copper ring to the column itself. This should be an open circuit, I believe. It is for the flasher but the horn ring is shorted to the column, almost, 2 ohms. Flasher ring to column is open, greater than 1,000 ohms, makes sense. Close inspection shows no issues.
Worst case, no flasher and the horn gets connected to the copper ring that is not shorted but I sure would like to have everything correct and working.Thanks for helping find the issue.
carl

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PostPosted: Fri Jun 16, 2017 7:20 pm 
356 Fan
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Joined: Tue Mar 25, 2008 6:32 pm
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Location: Harrodsburg, Kentucky
Tag: I wish I knew as much as I think I know.
Carl, first off are you connecting the horn and flasher to the right place. On the "A" car the button in the center is the headlight flasher and the ring is the horn operator. The two circuits are the same in that they use a carbon brush to contact the copper strip so there will be some resistance there. I cannot remember what the circuit contacts look like under the headlight flasher button but I suspect that the problem will lie there. Connect everything up and see if it works then start digging further if neither horn or flasher relays work.
I assume you have a workshop manual so you are not flying blind.

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PostPosted: Mon Jun 19, 2017 8:34 pm 
356 Fan
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Joined: Sun Mar 30, 2008 12:11 pm
Posts: 1440
Location: Los Angeles County
How are you measuring the 2 Ω resistance?

To accurately measure resistances that low you need a Wheatstone bridge or a very fancy and expensive Ohmmeter.

I'd recommend you hook things up press the button or horn ring and measure the voltage drop across the brush on the steering column. It looks like the horn button/ring ground one side of the relay so you probably should connect the negative voltmeter input to ground somewhere near the steering column and the positive voltmeter input to the brush on the steering column or the 85 terminals on the relays.

The horn [flasher] button and hornring work through a relay so a voltage drop of a fraction of a volt (probably even more) shouldn't hamper reliable operation.

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1958 Porsche 356A Cabriolet
1965 Porsche 911 Coupé
1966 Volkswagen Type 2
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PostPosted: Tue Jun 20, 2017 8:07 am 
356 Fan

Joined: Fri Dec 03, 2010 7:42 am
Posts: 218
Usually broad flat insulating spacers don't fail unless they are smashed. Look for a wire with failing insulation or a solder joint with a big solder blob. At 2 ohms some wire is touching the steering column. This isn't leakage through an insulator. This is contact.


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PostPosted: Thu Jun 22, 2017 3:52 pm 
356 Fan

Joined: Mon Sep 10, 2012 1:25 pm
Posts: 12
Thanks to all for the input. It sure looks like a unwanted connection between the upper copper ring and the column itself. I have put a insulative "sleeve" of the wire that exits the column for connection to the horn button all the way down to where it comes out of the column at the sleeve. Lifted the wire at the exit hole so it is not touching anything and the nearly short still exists. This may never be solved but I appreciate the ideas. I'm going with the assemble it all and see where we are. Thanks again.

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PostPosted: Thu Jun 22, 2017 6:10 pm 
356 Fan

Joined: Fri Dec 03, 2010 7:42 am
Posts: 218
Before you assemble it and hide it for ever, take a macro photo of the area where the wire is joined to the slip ring. I have never seen one of these things, so I don't know what insulating material they used beneath the slip ring. I would suspect a solder blob or a frazzled wire near the assumed solder joint to the slip ring. Usually close visual inspection with un-aided young eyeballs will reveal short circuits in technology of this vintage.


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