1968 Trouble with Horn

[retroman99]

Been trouble shooting the horns. initially neither horn would sound but did seem to be getting some indication of they were trying to go. when I pressed the horn button on the steering wheel

I suspected ground issue so when I checked that each horn was grounded properly and verified by directly hitting each of them with 12V from the battery they both gave a resounding "hello" so I believe I have confirmed that they are grounded properly and that they both work.
the strange issue is when I connect the electrical connections to both horns they don't work. when I just connect the passenger side it works when I try to connect just the drivers side nothing.
any thoughts where this gremlin might be hiding. All new harnesses. have not checked the horn button but since it works with just the passenger side connected it would seem it is working properly. I do recall seeing 2 contacts behind the steering wheel coming from the blinker switch assembly. could it be that one of those is not making contact?

 

[franklinair]

The horns are a 1 wire circuit from the steering wheel contact to the horns.
Here's a trick I've tried with some success:
Remove both horns, set them down in a position that they will hold penetrating (rust buster or LPS 1 type). Let them sit overnight, and then dump the oil out, and then try them. The oil will lube the diaphragms and free them up.
Let me know if it works for you.

Neil

 

[p51]

I had a similar problem where one horn alone would work ok but together either one or both would not sound.

There are adjustments you can make to the horns...
http://www.mustangandfords.com/how-to/interior-electrical/mump-1105-classic-mustang-horn-repair/

However, for me these types of adjustments didn't completely solve the problem. It appeared that what was happening was that the amount of current the horns pull cause enough of a voltage drop at the horns they they don't sound (or only sound partially as in my case). I fixed it by adding a relay (near one of the horns) from 12v to both horns that was controlled by the original horn signal. Worked perfectly. Now they are nice-n-loud.

 

[retroman99]

The horns are a 1 wire circuit from the steering wheel contact to the horns.
Here's a trick I've tried with some success:
Remove both horns, set them down in a position that they will hold penetrating (rust buster or LPS 1 type). Let them sit overnight, and then dump the oil out, and then try them. The oil will lube the diaphragms and free them up.
Let me know if it works for you.

Neil

thanks Neil
I will try that but it seems both horns will work if I hook them up to 12V. the passenger side is the only one that seems to work when it alone is connected. I have not tried to switch the horns to see if the drivers side will work when it is only connected to the factory wires. ill try that first then see about the penetrating oil. does anybody know if there are separate contacts at the steering wheel for left and right horns.?

 

[franklinair]

One contact. One wire (12 volts) running to the horns.
There is an adjustment screw on each horn that determines the tension on the diaphragm inside each horn. Sometimes turning the screw back & forth will help free up the diaphragm inside the horn.

Neil

 

[retroman99]

One contact. One wire (12 volts) running to the horns.
There is an adjustment screw on each horn that determines the tension on the diaphragm inside each horn. Sometimes turning the screw back & forth will help free up the diaphragm inside the horn.

Neil

thanks Neil
I decided to send my horns off to the Horn Works. let them restore them back to better than new. will see if that solves the problem.

 

[retroman99]

thanks Neil
I decided to send my horns off to the Horn Works. let them restore them back to better than new. will see if that solves the problem.

got the horns back. they look brand new and sound great! not cheap but they did a great job and turned them in 2 weeks. I'm glad it wasn't something else