Horn Stuck

doug.nichols

doug.nichols

Senior Member
I just finished installing a new rebuilt engine and a negative ground cut off switch. The car drives fine. When I reattached the light/horn wires to the alternator and closed the cut off switch, the horn started to toot and would not stop until I opened the cut off switch. Does anyone have an idea of what might be causing this? I have not done any work to the light switch, which is new a few months ago, and the horn is a new rebuilt 12v unit that worked fine before my engine change and switch installation. Is there a way to hook the horn up backwards? Any other ideas?

Thanks
 
Well it 'sounds' like you don't have a problem with power to the horn. If the button is not stuck it sounds like you have a short in the wire running from the horn to the button, thus completing the circuit. Inspect the wire coming from the horn to the light switch then the wire running up thru the steering column to the button.

 
Sometimes the horn contact spring in the center of the loom plastic switch plate contacts the upper rotating plate in the switch causing the horn to honk. I put a piece of shrink tubing around it, leaving the face of the contact open. Repro switches have a smaller hole for the spring so it happens more often with them.
 
Ray:

I will pursue your diagnosis to start. My wiring harness/switch/horn rod assemblies are all less than a year old and obviously repro units.

Thanks,

Doug
 
Is this an original type horn or is this a late type horn? Some late type horns may not have series wound motors. The original series wound type is not polarity sensitive. This may not have any bearing on your problem since the horn still has to have a completed circuit to function regardless of polarity.

The original horn is powered direct from the generator or alternator and the ground wire is the control wire to complete the circuit when the horn button is depressed. The horn button can sometimes have a failure inside that can cause a short. The wire inside the light switch rod can short due to bad insulation and complete the ground circuit. The wire from the light switch to the horn can also short and complete the circuit.
 
Thank you roto. The horn is refurbished from Berts a few months ago, so I am thinking it is probably ok. Likewise the wiring harness and horn rod are newish. However, I will look for shorts nonetheless. I will also open the light/horn switch assembly and look for horn contact issues ad mentioned by Ray.
 
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