[AndyM]

Im getting ready trouble shoot my horns and I'm reading my shop manual. It states
"open wire (yellow) from headlight switch to horn button" as one of the causes. What does the headlight switch have to do with the horn?

 

[AndyM]

I tested the connections with a voltmeter and when the horn is presses, the meter moves. I tried touching the horns straight to the battery and no sound. That means the horns are bad right?

 

[towcat]

You ground the horns and run a hot wire straight to the contact, and if it don't work, it's bad

 

[AndyM]

How would you ground the horn, its only got 1 tab? I did touch it directly with a 12 volt lead. If I'm getting a blinking current at the connector as tested by a voltmeter, wouldnt that also tell me they are bad?

 

[Leroy Reeves]

The surface of the horn that contacts the frame of the car when it is mounted is how the horn gets its ground. Applying 12V to the positive connection tab without the housing of the horn being grounded will not complete the circuit and the horn won't sound. You have to have the housing of the horn grounded either directly to the battery or through the frame of the car. The horn has to have some sort of metal to metal contact with the frame of the car when mounted.

 

[Bad69cat]

YEP sometimes the bolt/screw gets corroded and it doesn't make good enough ground to operate anymore....clean the contact points and give it a whirl

 

[AndyM]

I will check that tonight. I'm suspecting it's a ground that's bad. Anybody know what color the ground wire from the steering wheel is?

 

[Bad69cat]

Won't be one? Just the "Hot" wire....don't have my diagrams handy but may be diff on a 68 anyways

 

[Leroy Reeves]

there would not be a ground wire in the steering column for the horns, just the 12V positive. The horn switch just opens or closes the 12V wire that goes to the horns. The ground (negative) side of the battery connects to the frame of the car, making the entire frame of the car the ground. Any device on your car that only has a positive wire going to it is going to get its ground through its connection to the frame. You can use a bolt and nut to attach a wire to the horn where the mounting screw goes. Attach a positive wire to the terminal on the horn. Connect the other end of the wire that is bolted to the horn to the ground post on the battery. Touch the positive wire from the horn to the positive post on the battery. The horn should sound if it is good. if it doesn't work when directly connected to the battery, then there is something wrong with the horn. If you connect the positive lead that normally connects to the horn to the positive lead of your volt meter and connect the negative lead of your meter to the frame of the car or negative post of the battery and press the horn switch, you should see the volt meter move from 0 volts to 12 volts. When you release the switch, the meter should drop back to 0 volts. If you get 12 volts then that means your switch and wiring to the horn are in tact and your problem is most likely with the horn or its ability to get a good ground connection to the battery through its connection to the frame. If the horns test good and you have 12V at the positive terminal of the horn when the horn switch is pressed, try running a wire from mounting bolt of the horn to the battery ground post and retest. Sometimes these ground connections have to run through several bolt on brackets, body to frame connections etc... If the metal between these joints has been painted or corroded, then the parts become insulated from each other and current can't flow between them. You either have to disassemble and clean these contact points or add ground jumpers to bridge the joints. Sometimes it's just a matter of removing a screw that holds a bracket to the frame or body panel and cleaning the screw and the surfaces it contacts to get good metal to metal contact and the screw acts as the ground connection. I hope you find this helpful.

 

[AndyM]

that was very helpful. Thats kinda what I thought and the horn wires behave exactly like you say. each time the horn is pushed, the volt meter jumps. I will make sure the horn is grounded and let you know whats up. Thw reason why i was asking about the ground from the column it that I have 2 wires coming out (or going to) the column that are not connected to anything. They have plug in connectors. I cant remember what color they are but everything except the horns and the sequential signals seem to be working fine (see my other post about trouble shooting sequentials for that issue). I have good brake lights. I'm trying to get it to a point where i can get it inspected. Aside from checking the emergency brake, i need to put a new exhaust on it.