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| | | | Joined: May 2003 Posts: 183 'Bolter | | 'Bolter Joined: May 2003 Posts: 183 | The horn on my 1952 1/2 ton doesn't work when the engine is at idle. At highway speeds it works great. The truck is 6 volt. I have replaced the horn. I have added a horn relay. I have replaced the wire going up the steering column to the horn. My guess is, like most of the electrical problems with this truck, it is related to a bad ground. My understanding is when I press the horn button I am completing the ground connection (now that I have a horn relay this causes the relay to close). I'm guessing at idle the voltage drops enough to not close the relay.
How can I figure out exactly where the ground is failing? Is there something in the steering column that gets dirty/rusty that I can clean? Or add a ground wire to?
My dad always told me, "Don't force it, get a bigger hammer".
| | | | | Joined: Jan 2013 Posts: 1,384 Shop Shark | | Shop Shark Joined: Jan 2013 Posts: 1,384 | Testing is the best way to isolate a problem.
Check the battery voltage with the engine off. 6V or more good. 5.8 or less, not good.
The horn should get power even with the ignition off. Check for voltage it the horn, should be the same as the bat voltage. (if no voltage try with key on)
Take a length of #12 wire and connect it to the other terminal on the horn. Touch the other end to ground (There will be sparks)If the horn blows, the horn and power supply is good.
If horn doesn't blow, take a length of #12 wire and connect it to the power terminal on the horn. With the engine turned off, connect the other end to the battery or the battery wire on the starter(which ever is easier). Touch the ground wire to ground again. Horn doesn't blow, problem is at the horn. horn blows, good horn, bad power supply.
With the wire disconnected from the horn, engine still off, press the horn button and listen for the relay to click. Relay doesn't click, bad relay or wiring. | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | Are you sure you have a 6 volt horn & not a 12 volt.
Jim has some good tests. Put a jumper from the bat to the horn term. With the engine off it should blow. Make sure your bat is good.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | Where the contact completes the ground, those surfaces can be corroded inside wheel, under horn button, under contact plate. After the tests above, check there. Contact plate corrosion, bad contact plunger/spring, corroded/gummed mast bearing surface.
I read somewhere where there is a "voltage adjustment" screw at the center of the horn itself?
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: May 2003 Posts: 183 'Bolter | | 'Bolter Joined: May 2003 Posts: 183 | After following the testing suggestions above, I determined the horn and power supply were good. After removing the steering wheel, I discovered the contact plunger/spring was hanging up and not always making good contact. I purchased a new contact plate and contact plunger/spring.
Problem solved.
Thanks for all the help.
My dad always told me, "Don't force it, get a bigger hammer".
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