Horn wont work, kinda unique problem SOLVED

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Thanos

Thanos

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OK I'm hoping someone can help. 71 Demon, original s/6 now 318 with console shift and I believe this along with the steering column switched out. Old restore, whomever did this did an excellent job on the console shift short of wiring lights to it, but that's not the problem...
I've been tiring to get the horns to work. Horns work on direct 12v, wiring from horns to bulkhead is intact, green w/red , tested with volt meter, and with 12v from bulkhead connector but on the inside of the bulkhead the wire is yellow w/blk and runs to the headlight buzzer. I've been using a 71 Dart diagram for the wiring and it shows that it should be green w/red running from relay to bulkhead. I cant seem to find a diagram that shows a headlight buzzer. Here is a pic of where it runs from the bulkhead. There are 2 black wires, one black from relay and the yellow w/blk from the bulkhead. One of the black wires is connected to the Yellow w/blk but I don't know where it goes from there.
IMG_20170419_214627.jpg

Here it is connected to the 2 wires that run to the buzzer. The buzzer is under the glove box and works correctly when the headlights are on and door open.
IMG_20170419_214800.jpg

Here is a pic of the horn relay
IMG_20170419_214432.jpg

I took the relay apart to clean an test. It is working properly. Press the horn and it clicks, conductivity is good thru the contact. But no horn. I cant find where the green w/red terminates. If anybody has a setup like this I'd like to know how it works. I'm guessing the other black wire tied into the yellow w/blk has something to do with this.

Also there is this
IMG_20170419_214955.jpg

I think this is for the key buzzer but I have no idea where it goes. Its not on my diagram ether and I'm guessing its for a newer model. Nether buzzer is that important to me as I want the horn to work but I would like to have this wired properly. Any help is appreciated.
 
Horn unit itself...poor ground, maybe? When you read the power at the horn (two wire?) one power, one ground, I understand you are getting power there? Can you slave into the connectors (while connected) at the horn and read the power when horn is activated? Power drop from high resistance from the relay?
Norm
 
You need to go over to MyMopar if you have not and download a 71 shop manual. Plymouth, Dodge, does not matter

Now there is a MISTAKE for several years concerning this circuit in the shop manuals. The T and L pin of the bulkhead connector is mis-drawn. BUT IT WOULD have been correct when original. Just look at what pin the green / red goes to on the engine side, and that is where it should come out of on the interior, unless someone has messed with the connector. IT MAY BE that the bulkhead connector itself is where you are losing connection. You should be able to trace the green/red from the relay to the horns. One way is to simply jumper battery power right to the green/ red at the relay. The horns should operate or a test light at the horn end should light

Judging from the crimp connectors in your photo..........the wiring HAS been fiddled with?

MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

Download the 71 Plymouth chassis manual:

http://www.mymopar.com/downloads/servicemanuals/1971_Plymouth_Chassis_Service_Manual.zip

The interior side is shown page 8-160 (381) and the engine bay side is 8-151 (372)
 
circlepilot said:
Horn unit itself...poor ground, maybe? When you read the power at the horn (two wire?) one power, one ground, I understand you are getting power there? Can you slave into the connectors (while connected) at the horn and read the power when horn is activated? Power drop from high resistance from the relay?
Norm
Click to expand...

Horns only 1 wire, grounded on body. I read good 12v coming off relay to the green w/red wire. And that's the problem. Power is going to the correct wire from the relay according to the schematics but there is no power at inside bulkhead which is the wire that runs to the headlight buzzer. And no there is no splice at bulkhead, look here
71Dart.jpg
 
67Dart273 said:
You need to go over to MyMopar if you have not and download a 71 shop manual. Plymouth, Dodge, does not matter

Now there is a MISTAKE for several years concerning this circuit in the shop manuals. The T and L pin of the bulkhead connector is mis-drawn. BUT IT WOULD have been correct when original. Just look at what pin the green / red goes to on the engine side, and that is where it should come out of on the interior, unless someone has messed with the connector. IT MAY BE that the bulkhead connector itself is where you are losing connection. You should be able to trace the green/red from the relay to the horns. One way is to simply jumper battery power right to the green/ red at the relay. The horns should operate or a test light at the horn end should light

Judging from the crimp connectors in your photo..........the wiring HAS been fiddled with?

MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

Download the 71 Plymouth chassis manual:

http://www.mymopar.com/downloads/servicemanuals/1971_Plymouth_Chassis_Service_Manual.zip

The interior side is shown page 8-160 (381) and the engine bay side is 8-151 (372)
Click to expand...
I have taken the bulkhead connectors apart and cleaned them. Good conductivity thru them at L. The splices you see in the back are the speaker wires. Radio itself is connected to a relay under the hood, it turns on from ignition. I did hook the battery directly to the yellow w/blk and horn sounds.
 
The Green/R MUST come to and go through the bulkhead on one pin. It surely is either T or L It's ONLY job is to carry switched 12V from the horn relay, through the bulkhead, and out to the horns. NO OTHER wire should be spliced into that.
 
The horn circuit is pretty basic. There is a wire going from the relay to the horn switch in the steering column. When the horn button is pressed, it completes a ground and allows the 12 volts to flow through the horn relay through that ground. The current running through the relay activates the magnet and connects the 12 power to the wire going out to the horns. So I would do this:
1. Check The fuse. Simple, but easy to overlook. using some kind of a circuit tester, make sure you have power on both sides of the fuse. A fuse can look good but not have continuity.
2. Test the hons by unplugging them and use a jumper wire to give them 12 volts. If they work, good. If they don't work, it is either a bad horn at a bad ground. In that case make SURE the horn is properly grounded and give it 12 volts again. If it works, then the ground was the problem. If a properly grounded horn does not honk with 12 hot volts, you have a bad horn.
3. Once you are satisfied that you have good horns, use a circuit tester to see if you have power coming into the horn relay. If you do then press the horn button and see if the going out to the horns becomes hot (with 12 volts). If it does not, then you either have a bad horn relay or the horn switch in the steering column is bad. To test the horn switch, ground out the wire going to the steering column by the easiest means you have. That will do the same thing as pressing the horn button. If a horn relay that has 12 volts going into it does not activate when grounded directly like this, it is bad. If it does activate now and allow current to flow out through to the horns, then the relay is good, but either the horn switch is bad or there is a continuity break between the relay and the horn switch. In this case, take the steering wheel off and try grounding the round copper ring. That should activate the relay. If it does, continuity is good, ans cleaning everything up with some 600 grit will likely solve the problem.
4. If the relay is working and allowing current to flow out through to the horns the problem is a break in continuity between the horns and the relay; most likely at the firewall connector. One last test you could do is to run a wire from the known good relay directly to the horn. If it works now, you definitely have a break in continuity between the horns and the relay to find. Hope this helps. Feel free to PM me for more help. I am pretty good with this stuff.
 
67Dart273 said:
The Green/R MUST come to and go through the bulkhead on one pin. It surely is either T or L It's ONLY job is to carry switched 12V from the horn relay, through the bulkhead, and out to the horns. NO OTHER wire should be spliced into that.
Click to expand...

Sorry 67Dart, the Valiant schematics, which should be the same more or less, shows engine side L for horns (where it is on my car) but inside is T and that cannot be as T comes off the starter relay. But I think I'm getting closer, the schematic DOES show how the headlight buzzer wires in and its association with the horn relay, and I think the problem might be in the steering column. As I said I don't think its original. Ill crack it open tomorrow to have a look.
 
OK, after a good nights sleep and long day at work I went at this again an 67Dart I owe you. While the schematics didn't match they did show me how the headlight buzzer should be hooked up so I pulled the whole bulkhead connector off an sure enough I found a cut and bypassed wire...It ran to the buzzer while the horns were attached to said cut wire. It looked connected and when I ran power thru it at the bulkhead the horns would honk but I couldn't see it was cut till I pulled it all out. That's also why I couldn't get a reading from the wire in the relay even tho the relay was working. The guy who put this together must have mixed up the horn an buzzer wire and said screw it an bypassed it as it had no horns anyway. By the way the horns I bought were for a 2009 Charger, MOPAR original, guy just wanted air horns. Couldn't believe that they used the same one wire as my Demon did. Sound great and even used original brackets to mount them.
 
I got one for ya! 71 demon new horn relay and 1 day the lower horn quits. no reason I can find! upper horn honks when horn button is pushed but with lower horn wire attached it only makes bonk sound and shows drop on amp hand. I can unhook the wires from the lower mounted horn and the upper one works fine when horn button is pressed. I can jump 12 volts to the lower horn and it works perfect as will both when 12 volts are jumped directly to the lower wires. this is crazy to me! Is the lower horn drawing to much current? All wires are connected the relay is new so I give up?
 
My guess would be voltage drop in the wiring harness. If jumper direct from battery works, very close to the same power should get there through the many connections involved. Crusty fuse clips, bulkhead connectors, etc..?
 
One issue to store away in your memory banks. Horns that won't work, have seen this issue. A horns tone can be adjusted by a small screw on the back of the horn. I have had a couple of cases where that adjusting screw is frozen to the inner diaphragm, so that the diaphragm won't vibrate and produce a sound. The solution is to simply rotate the adjuster screw back and forth a 1/4 turn to free it up.
 
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