Two Circuits for Horn??
06-03-2015, 10:38 PM
#1
Two Circuits for Horn??
I am traveling and have not had the time to research this further, but thought I would post a question here on the forum in the meantime.
Just before I left I notice the horn stopped working. After I parked the car I started to take off the steering wheel center, i.e. horn button, and as I did the horn sounded. Apparently the horn does not work while driving, but does after the power is turned off and parked.
Are there two separate circuits that power the horn?
Just before I left I notice the horn stopped working. After I parked the car I started to take off the steering wheel center, i.e. horn button, and as I did the horn sounded. Apparently the horn does not work while driving, but does after the power is turned off and parked.
Are there two separate circuits that power the horn?
06-04-2015, 03:14 PM
#3
RL Community Team
Rennlist Member
Rennlist Member
This info pertains to my '79, but I'm assuming it's likely the same for all years, and I just completed the troubleshooting of why my horns wouldn't work.
The horn circuit has power all the time so the horn would actually work when parked, like if someone is backing into you before you've started your car. The horn circuit works by completing the ground connection to the contact on the turn signal, headlight, cruise assembly, which is connected to the ground on the horn relay. Once you have the wheel off you can see the spring assembly that's always in contact with the ring on the back of the steering wheel. When you push the horn button or pad (depending on your wheel) it completes the ground circuit which then allows the horn to sound. Someone would really have had to mess with your wiring for the horn to only be functional with the ignition off and not on. The only way I can see for this to occur is if they disconnected the + wire of the horn circuit that goes into the steering column harness and hooked it up to a wire that's only hot when the car is off, and I can't really think orf a circuit that meets that criteria. Do some testing with the ignition on and the ignition off and the steering wheel in different rotated positions. You might find that part of the contact ring on the back of your steering wheel has some corrosion or debris on it that does not let the horn buttom complete the ground when in a particular position.
If anyone is intersted, it turned out that I had 2 separate problems - one was that one of my trumpet horns itself was internally shorted and since both of them are hooked to the same circuit and in series, the short in one would blow the fuse and neither would work. 2nd issue is that the spring contact on the turn signal assembly in my car was completely gone so it never made contact with the ring on the steering wheel. I repaired it by taking two pieces of copper home wiring, forming it to the shape of the black plastic piece that normally holds the spring clip, melting them into the plastic, solder connecting those two wires to the contact in the plastic block, then sanding all of that smooth so it wouldn't cut into the ring on the back of my steering wheel. I also replaced my horns with 2 compact Wolo "Bad Boy" air horns connected through an SPDT relay to draw current directly from the battery - you can certainly hear my car now - only problem is when I blow the horn, people keep looking around for a train
The horn circuit has power all the time so the horn would actually work when parked, like if someone is backing into you before you've started your car. The horn circuit works by completing the ground connection to the contact on the turn signal, headlight, cruise assembly, which is connected to the ground on the horn relay. Once you have the wheel off you can see the spring assembly that's always in contact with the ring on the back of the steering wheel. When you push the horn button or pad (depending on your wheel) it completes the ground circuit which then allows the horn to sound. Someone would really have had to mess with your wiring for the horn to only be functional with the ignition off and not on. The only way I can see for this to occur is if they disconnected the + wire of the horn circuit that goes into the steering column harness and hooked it up to a wire that's only hot when the car is off, and I can't really think orf a circuit that meets that criteria. Do some testing with the ignition on and the ignition off and the steering wheel in different rotated positions. You might find that part of the contact ring on the back of your steering wheel has some corrosion or debris on it that does not let the horn buttom complete the ground when in a particular position.
If anyone is intersted, it turned out that I had 2 separate problems - one was that one of my trumpet horns itself was internally shorted and since both of them are hooked to the same circuit and in series, the short in one would blow the fuse and neither would work. 2nd issue is that the spring contact on the turn signal assembly in my car was completely gone so it never made contact with the ring on the steering wheel. I repaired it by taking two pieces of copper home wiring, forming it to the shape of the black plastic piece that normally holds the spring clip, melting them into the plastic, solder connecting those two wires to the contact in the plastic block, then sanding all of that smooth so it wouldn't cut into the ring on the back of my steering wheel. I also replaced my horns with 2 compact Wolo "Bad Boy" air horns connected through an SPDT relay to draw current directly from the battery - you can certainly hear my car now - only problem is when I blow the horn, people keep looking around for a train
