Why does it shock me??

[HELENT]

Original 1946 Ford steering column, when I blow the horn with my arm in the window it shocks the crap out of me. I have checked all grounds.

[Mike51Merc]

This has been discussed before so maybe you can find the thread with a search. A popular theory is that the collapsing magnetic field in the horn causes a reverse voltage spike that may be as high as 100 volts. I'm not kidding.

[zzlegend]

LOL,,,,,Sorry,,,,,I just fell out of my chair.

[V8COOPMAN]

Almost sounds like the steering column/gearbox is not SUFFICIENTLY grounded to the chassis. DD

[Bruce Lancaster]

It has to be something inductive happening in the coil inside the horn relay, as 6 or 12 isn't going to do this.
When it happened to me after I rewired my '48...the shock was enough to lift me out of the seat...I had to swap two of the three wires on the relay to the other terminals and that did the job.
I can't say that I really understand the problem, but that was the cure. This was with the car's original relay and wiring following the book...aside from my having gotten the two smaller wires on the wrong terminals!

[Mike51Merc]

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Bruce jogged my memory, it was the induction from the relay not the horns. Energizing the relay coil causes a magnetic induction backlash when the coil power is shut off. Just like an ignition coil works.

I know it sounds hokey, but it is theoretically sound. After all, 6 or 12 volts isn't enough to shock you through your skin.

See if it shocks you when the horn is blowing, or instantly as you release the horn button.

Or get somebody to hold it for you, just like when you want to test a sparkplug wire for spark.

[ken ct]

That exact thing used to happen on my father's 49 Cheby once in a while dont remember how he had it fixed.He was not car minded LOL ken ct.

[32phil]

Had a 48 coupe(nice car all totally redone) that did that too. I went to the Doctor, I told him when I do that it hurts...he said..... don't do that and it won't hurt anymore. Anyway...I never did find out why that car did that either. It was a killer to start too. I finally sold it a few years ago out of frustration. It wouldn't start the day I sold it and when I finally got it going it shocked me! Glad that POS is gone.

[Willit Stop]

It must be a later Ford "open window warning system". My '36 doesn't have that feature. Just kidding,hope you find the problem.

[Carbroke]

Put a diode across the inductive load such that it is reverse biased when energized. When you open the horn switch, the diode will dump the induced voltage back across the inductive load, saving you a shocking experience.

[ford3]

i believe the horn relay is the problem, either missing, by passed or its wired wrong, the relay should stop any elecricty from backing up from the horn windings to you

[Gary in La.]

My '46 did the same thing some years ago. I cured it by re-establishing good grounds in the system and with the horn mount bracket to inner fender shield. never did it after that.

[rotorwrench]

I use what is called a Transorb (very much like a diode) on all the relays of one brand of helicopter I work on. The manufacturer's service bulletin explained it as transient voltage supression. The helicopters use 24-volt systems so it could be a shock sometimes but they were more worried about the high dollar avionics getting damaged than anything else.

[Bruce Lancaster]

On mine, the car had its original relay and with its original (disintegrating) wiring it worked fine with no shocking. I rewired the car, following original diagrams, with modern wire (back then the only other choice was NOS, and all I found was too brittle to be trusted) and horn worked fine but would lift me out of my seat with a shock. I swapped the wires...I think I followed all the wires and figured out the wires were reversed, changed them, and that solved the problem.

[Mike51Merc]

Does anyone know whether a capacitor can be used as a buffer? Or would the capacitor just hold the charge until the next opportunity of discharging?

[Vic Piano]

This is a more common problem than I imagined... the '47 LC (we've been playing with) also had the shocking horn problem. I say "had" because I disconnected the hot lead from the horn relay. I thought it might be a problem with the horn button, spring, etc. as the steering wheel had been previously removed (for what reason I don't know,yet) and replaced in the wrong position. Another electrical problem to be ironed out with this car...

[rotorwrench]

The Varistors we use are the ZA series from Littlefuse. The V47ZA7 that we use would be overkill at 30-volts DC but a V18ZA type would work for the 6 to 8-volt systems. A 10mm disk size should do the trick. These are like two Zener diodes put back to back in the way they work. They are wired in between the power coil terminals of any solenoid type that you can attach them to. We crimp ring terminals on for the big relays & solenoids and solder the little relays used for intercomm systems

[Ross6860]

Originally Posted by Mike51Merc

Does anyone know whether a capacitor can be used as a buffer? Or would the capacitor just hold the charge until the next opportunity of discharging?

You use a diode.

We do this on all our control panel relays.

[Chuck Sea/Tac]

Some refg equipment has a quencharc a cross the line solenoid valve. It's a combo capacitor/resistor. This absorbs the collapsing wave, which will sometimes trip the GFI. It's a drag to find your reefer has been off all nite!!

[pineapple]

Ha Ha, I thought this nonsense only happened to me. I completely re-wired my 51 f1 (12 volt negative ground). Everything works just Jake, except when I honk the horn with my arm out the window..Big shock..I figured a ground reversal problem that I was to live with...I will reverse the wires like Bruce said..

Matt.