When I started the project to repair my horn I did a search to see what other people had done to fix similar problems. I found out it's a fairly common problem but didn't find anything that showed a repair other than replace the horn pad.....if you could find a working one. I posted this in my build thread, but figured it might come in handy for some other folks and be easier to find here so I'm double posting it.
When I was doing the under dash wiring on my truck, I noticed that the fuse for the horn was gone…….when I put a fuse in I found out why, the horn would not shut off. I decided to leave the fuse out and leave it for another day.
The “another day” came yesterday when a non-driving, mouth breather of an old fart ran me in into oncoming traffic when he didn’t check his mirrors or use his turn signal before deciding to occupy the lane I was in. With no horn all I could do was grab a gear and go around him.
So yesterday afternoon I decided to fix the horn. The first thing I did was check the wiring diagram. The D50 doesn’t use a horn relay, the horn has power anytime the key is on and the horn pad on the steering wheel is used to complete the circuit to ground. With no relay that left the wiring being shorted or the switch in the pad being bad. I figured the most likely culrprit was the horn pad, so I took that off first.
To get the pad off the first step is turn the steering wheel upside down and removing the screw on the bottom.
With the screw out, you press in on the bottom of the pad and rotate the bottom away from the steering wheel slightly, then pull the pad toward you to release the clips that hold the top of the steering wheel. Unplug the wire and the pad is free.
Next I worked the vinyl cover over the nylon inner liner with a small screwdriver until the cover was able to be pulled off. If you decide to do this in cold weather, take horn pad indoors or set in the sun, the vinyl is a lot easier to work with when it’s warm.
With the cover off, I found the problem. There is a thin copper circuit board piece that is what makes contact to complete the ground circuit. It appears that originally there was a piece of thin foam with holes punched under each of the little crosses. Over the years the foam had deteriorated and allowed the plate to make contact all the time.
In order to hold the plate away from the base that it was grounding against until you pressed on the horn pad, I cut some (1/4” wide) strips of old seat foam I had laying around and put them between the plate and nylon base. I used a thin bead of silicone to hold the foam in place.
The last 2 steps were to reinstall the vinyl cover working the lip back over the nylon inner form, and check it with an ohm meter.
The horn now works, but let’s face it the stock horn is pretty anemic and when I use it I want people to hear it. I happened to have a spare insulated horn (you can’t use one that grounds thru the mounting bracket, it has to have separate terminals for power and ground) in my parts stash, so out came the grill and the second horn was mounted on the left side of the radiator support.
I unplugged the wired from the original horn so I could splice the new wiring for the second horn, hooked them both up and put the grill back in. It pretty much sounds like a small train now.
Nicely done Mike. I have a real nice two-tone air horn that I have yet to find the right place for it to fit. I've tried a bunch of different angles but still can't get it in there snug and still have room for everything else. Some day!
Kudos to you Mike. A horn seems like a fairly trivial thing to have malfunction and a lot of people just pull a wire or a fuse and live with it. But it being there when you need it can be the difference in a life and death situation (plus it is illegal to drive a vehicle without a working horn). This is a good little write up on a repair that anyone could tackle. Only thing that you could add to the repair is cleaning the copper contact plate for a good connection.
Air horns are the ultimate fun toy I will never do without. The first time I hit mine at a sleeping motorist waiting for a pole to turn green and seeing how high they jump out of their seat, I was sold. Instant reaction.
Originally Posted by Uncle Spence
It's awesome when people document this stuff so others can benefit later!
I went through this when I got my truck. Didn't realize it until I failed inspection because of it! Quick fix using foam I use in my aquarium filter.
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