Phoenix8990

My horns were working recently but have stopped. When I press the horn I can hear the relay clicking but no sound. Any suggestion? I had a spare horn relay but don't recall if it was good or not and it did the same thing. I am confident the horns are fine. The horns are connected.

thanks,
Steve

ourkid2000

Start with this. Take the connectors off at the horns......with a test light connected to a known good ground, insert a test light into the horn connector . Honk the horns and look for light. If it lights, your horns are either not working or have a corroded ground where they bolt to the body.

oldcutlass

Or you can just jumper the output side of the horn relay to 12v. If the horns activate, then it's probably the relay.

ourkid2000

Yep, that's the easiest quick and dirty test. With those two tests should be able to narrow the issue down in about 5 mins.

joe_padavano

Good start, but you jumped to a conclusion.

Look the horn circuit is pretty simple, as is troubleshooting. Don't replace parts until you are sure of the problem. I just went though this on my new 69 Cutlass wagon.

1. Disconnect the green wire from the horn relay and jumper it to 12V. If the horns work, they are fine. If not, fix the horns.
2. Reconnect the green wire, disconnect the black wire, and jumper that terminal on the relay to ground. If the horns work, the relay is fine. If not, check for 12V on the junction stud. Clean all those terminals. If this still doesn't fix the problem, replace the relay.
3. If the relay tested good, the problem is in the black wire between the relay and the horn button. Reconnect the black wire. Disconnect the turn signal connector at the base of the steering column and jumper the black wire in the connector to ground (third wire in from the end - some have two black wires). If the horn works, the problem is in the turn signal switch or the horn contact in the steering wheel. If the horn doesn't work, find the open circuit between that connector and the horn relay - very likely in the firewall connector.
4. Reconnect the turn signal switch connector. Remove the steering wheel, lock plate (if 69-newer), and cancel cam. Short the horn contact button on the turn signal switch to the steering shaft. If the horn blows, the problem is the cancel cam or horn button. If not, the problem is the turn signal switch.

I literally just did this last weekend for my 69. The problem turned out to be a bad cancel cam.

Phoenix8990

Thanks for the suggestions. I'll work my way down Joes list later today and will update.
thanks,
Steve

Phoenix8990

So after testing it appears both horns decided to die at the same time. That just doesn't seem right. What would cause that?

Steve

joe_padavano

Are you sure one hasn't been dead for a while?

Sugar Bear

There is no sound reason...

Fun71

Yeah, it's kinda like when folks say both high beam headlights burned out at the same time.

Phoenix8990

It is definitely a possibility that one was bad but I just bought them from someone on the site a year or so ago. I guess they just didn't have much life left in them. I just wondered if a power surge or something would do that. Not that I can see that happening.

thanks all,
Steve

ourkid2000

My '66 Toronado had a non-working horn when I first got it. It took me about 5 mins to find that I had a dead horn relay. Not only that, but I only had the high note horn when I jumpered the feed to the horns. Not long after, during my testing, I lost the high note horn as well so they do go bad. I guess mine had been out of commission for so long that when I actually put power to them, the only working one started to malfunction as well.

I popped the top off the horn relay to find that the little coil inside was just floating around inside the case so I knew that needed to be replaced. I removed the horns and put them on my bench power supply hooked straight to 12V. One was completely dead and the high note horn would only honk when I wacked it with a rubber mallet.

I drilled out the rivets and separated the halves to find that the insides had corroded. The horns use a set of points to operate and they were terribly corroded but that was easily cleaned up with some De-oxit and a bit of emery paper. It was a bit tricky getting them back together as you have to get the gasket thickness correct. I had to use two paper gaskets sandwiched together and a small amount of RTV and used screws to put it back together. Adjusted them on the bench using the method in the manual and they work perfect once again after I replaced the horn relay.



Corroded points


Cleaned up, reassembled, painted. Used screws to reassemble.

Phoenix8990

I never thought about what's inside a horn, not much. I'll give that a shot, I've got nothing to lose. Buying another set of used horn may give me the same problem in 6 months.
thanks,
Steve

ourkid2000

Yeah, once you have the screws in there and figured out the gasket, they become very serviceable afterwards.

joe_padavano

Kudos for that! I'm also particularly impressed with the use of tri-wing fasteners.

ourkid2000

Many years of being an aircraft technician working on Bombardier Dash-8's has left me flush with old hardware. Might as well use what I got! Good eye!

joe_padavano

Interesting. We primarily use Torq-set fasteners on space hardware.

ourkid2000

Bombardier used those on the 900's (or Crj900 I should say). Not a Phillips or a Triwing to be found on those things. I've got tons of Torq-set in my box as well. I guess the Canadair arm decided they were better than tri wing for whatever reason but it makes it a pain to service due to the variety of fasteners on the different aircraft we fly.

matt69olds

🥁