Horn shocks! – california association of sunbeam tiger owners forum electricity for refrigeration heating and air conditioning answer key

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In your posts, you mention a horn relay. To what are you referring? I am not aware of a relay (a low-amp switch that operates a higher amp switch) as part of the stock horn system. Attached is a wiring diagram for a Mk 1A Tiger. I believe the horn wiring system is identical for Mk 1 and Mk II Tigers.

The wire from the battery connects to a spade (No. 3 on diagram) on the back of the ignition switch. On that some spade is a brown wire that goes to a terminal (No. 1 on diagram) on the fuse box. This is unswitched. On the other side of the fuse (No. 2 on diagram) for that terminal are two purple wires, each one going to one of the horns. (One of those wires has a "take off" going to the map light and the other wire has a take off for the interior lights for GT models.) Coming off each horn is a purple with black stripe wire going to the horn (push) switch, which is a slip ring. When you push the horn ring, it closes this switch and the amps can then go to ground.

If you are getting shocked by touching the steering wheel spokes while pushing on the horn ring, it sounds like the 12v at the horn switch is not able to go to ground through its ground wire when you push on the ring, and is instead finding a ground through the horn ring to you, then to the steering wheel spokes, and then to the steering column. You might want to check the resistance from the horn switch to another ground point. I suspect that the ground connection on the wire from the horn switch is not good for some reason. Have you tried disconnecting the horn switch ground wire from the ground, clean the terminal on the wire and whatever is the ground point, and see what happens?

What is perplexing is that I did not think the horn ring got "hot" when one pushes on the ring to sound the horn, but it has been awhile since I looked the horn slip ring and how things were connected. I always thought the horn just would not sound if there was a problem with completing the circuit to ground when pushing on the horn ring.

I do recall that there is a big, fat screw on the underside of the clam shell steering wheel column cover. If one is not careful when reassembling this, that screw can go into one of the wires for the horns or turn signals. You might want to check that as well.

You are right, the original did not have a horn relay. When I wired the car there was a horn relay added to the left side, both horns were mounted there. I replaced the old horn relay and wired the ground coming from the horn ring to the ground of the relay and broke the 12v horn supply thru the relay. During a subsequent conversation with the owner I learned that he had added the horn relay for an electric radiator fan, a fan that was not on the car when we received it for building.

The turnsignal mechanism casting was broken, no replacements are available. I found a similar casting and machined it to work the turn signals, the horn ring contact arm would not work with this piece so I made a new mountings for it and polished the contact points. The actual contact felt firm and positive, I didn’t take ohm readings, I’m sure it was zero. But I do know what you are thinking. It seems the problem must be right there. I am looking at making jumpers to bridge the universal joints, I’ll be doing that this morning.

In your posts, you mention a horn relay. To what are you referring? I am not aware of a relay (a low-amp switch that operates a higher amp switch) as part of the stock horn system. Attached is a wiring diagram for a Mk 1A Tiger. I believe the horn wiring system is identical for Mk 1 and Mk II Tigers.

The wire from the battery connects to a spade (No. 3 on diagram) on the back of the ignition switch. On that some spade is a brown wire that goes to a terminal (No. 1 on diagram) on the fuse box. This is unswitched. On the other side of the fuse (No. 2 on diagram) for that terminal are two purple wires, each one going to one of the horns. (One of those wires has a "take off" going to the map light and the other wire has a take off for the interior lights for GT models.) Coming off each horn is a purple with black stripe wire going to the horn (push) switch, which is a slip ring. When you push the horn ring, it closes this switch and the amps can then go to ground.

If you are getting shocked by touching the steering wheel spokes while pushing on the horn ring, it sounds like the 12v at the horn switch is not able to go to ground through its ground wire when you push on the ring, and is instead finding a ground through the horn ring to you, then to the steering wheel spokes, and then to the steering column. You might want to check the resistance from the horn switch to another ground point. I suspect that the ground connection on the wire from the horn switch is not good for some reason. Have you tried disconnecting the horn switch ground wire from the ground, clean the terminal on the wire and whatever is the ground point, and see what happens?

What is perplexing is that I did not think the horn ring got "hot" when one pushes on the ring to sound the horn, but it has been awhile since I looked the horn slip ring and how things were connected. I always thought the horn just would not sound if there was a problem with completing the circuit to ground when pushing on the horn ring.

I do recall that there is a big, fat screw on the underside of the clam shell steering wheel column cover. If one is not careful when reassembling this, that screw can go into one of the wires for the horns or turn signals. You might want to check that as well.

You are right, the original did not have a horn relay. When I wired the car there was a horn relay added to the left side, both horns were mounted there. I replaced the old horn relay and wired the ground coming from the horn ring to the ground of the relay and broke the 12v horn supply thru the relay. During a subsequent conversation with the owner I learned that he had added the horn relay for an electric radiator fan, a fan that was not on the car when we received it for building.

The turnsignal mechanism casting was broken, no replacements are available. I found a similar casting and machined it to work the turn signals, the horn ring contact arm would not work with this piece so I made a new mountings for it and polished the contact points. The actual contact felt firm and positive, I didn’t take ohm readings, I’m sure it was zero. But I do know what you are thinking. It seems the problem must be right there. I am looking at making jumpers to bridge the universal joints, I’ll be doing that this morning.