‘37 model 78 horn problem
 

(2nd attempt at posting this question—apologies if there’s a duplicate somewhere)
Hello! I’m hoping to tap into the collective wisdom on this board to get the horns on my ’37 to function properly. They worked well until recently, but I don’t think there was a specific incident that did them in—at least not one that I’m aware of. When I press the horn button, both horns make a clicking sound, but if I wire them directly to the battery they blast away. The wires are delivering a full six volts to the horn, but clearly not with enough oomph. The wiring in question is either original or very old and comes out of a cloth-bound harness. The lights, also in that harness, work perfectly. I suspect that the only solution is to replace the whole length of wire from the horn to the button, but I don’t want to go to all that trouble without proving that it isn’t something else. The battery is in good condition, fwiw.

The manual for the car is spectacularly unhelpful, though it has a section on the horns: “The horn requires no lubrication and should require but little attention.” Any help sincerely appreciated.

Re: ‘37 model 78 horn problem
 

You don't mention grounding which I think is the problem but your test results are puzzling. The 37 Ford horns have two leads; one is connected to the battery (solenoid terminal) and the other to the horn button for grounding when the horn button pushed. The horns are not very accessible.

When you connect them to the battery, they blast away. Well, they shouldn't unless you ground the other wire in some fashion. Do you press the horn button in this test? If not how do you ground the other terminal? I would think if you grounded it through the horn button, you should get the same click which means the horn ground is inadequate.

Without the external 6 volts applied, you should have 6 volts on one terminal. If you press the horn button and the voltage does not drop, then it is providing enough current. Then with the horn still depressed, check the voltage on the "ground" side of the horn. It should be near zero. If not the horn ground is not adequate. Look at the horn ground and clean up any corrosion (which could be at the bottom of the steering gear)

Ford had a better idea for 1938 by having a relay deliver 6 volts to a single wire horn and grounding the horn to the frame. You could do the same with your 2 wire horn if having trouble cleaning up all the connections.

Re: ‘37 model 78 horn problem
 

This may be helpful. 1937 Wiring Diagram

Re: ‘37 model 78 horn problem
 

Very nice diagram...
https://www.fordbarn.com/forum/attac...8&d=1753311871