Horn Relay

This might of been covered before but I have not been able to find anything in the search. I am trying to figure out where the horn relay is on my 68'. I was able to get another set of horns that are said to be good and I still only get a clicking when I hit the horn switch on the wheel. I see in the electrical diagram that there is a horn relay, but not sure where it is at. Also not sure if this problem is the relay, the fuse, or if it is in the steering wheel area?
Any ideas and help is great.

Thanks

have you removed the steering wheel /horn cover plate???

my 1st thought is to check the groung or are the horns bulted up tight.?? i'm not sure about a horn relay. i can try and look in to this,,,

I kinda thot this little beastie might be a horn relay if they are set up anything like a chevy.

This little mess was in the DS rear of the DH on a 66 van
Im just guessing tho on what it is...

Thanks for the help. I have tried to get any noise out of the 4 different horns that I have on a bench using a battery charger and still have nothing. I was able to find the relay by tracing the clicking noise that was made by the horn switch. Tried to check to see if that was good but am not sure on that either. Going to go out and see if I can buy a plastic horn to see if the rest of the system works and I just have 4 bad horns or if something else is not working right. I will post pics when I get something figured out.

I just went through this with my brothers car as 1 of his wouldn't work. There's a screw on the back of the horn. Remove it and spray some PB Blaster or Liquid wrench in it and shake it up. Let it sit few about a hour and them drop the horn or bang it on a table a couple times. Give it a good shock as this will break free the contacts. Re install the screw and adjust as needed to get the sound back. What happens is the contacts get rusted and causes horn problems. Good Luck

I have done that with both of the horns and have beat on them with a rubber mallet for over a good month. Have not dropped them but figured that if they were going to let go that they would do it by now. As for spraying them, have had it dripping out of the seams so know there is plenty of juice in it. Going to see if I can get a cheep $20 horn to see if the system works. I have not taken the cap off the wheel to see what is going on in there but know that it is making contact as it makes the relay click when hit. I was not sure if a relay will click but not shove enough power through the system to make the horn blow?

OK this is really a pain in the @s@. Here are the things that I have done and still sitting where with none functioning horns. What I started with was just a clicking sound of the relay, which is under the dash, when the horn switch on the steering wheel is pushed down.

1) take old horns off and remove the tone screw and soak the insides with PB Blaster, hitting them with a rubber mallet and also with an alum bar. (trying to break loose diaphram or moving parts)

2) tested on a spare battery, negative to mounting bracket and positive to post on horn. (No sound)

3) bought another set of vintage horns that were to be a working set and put on truck with same results as original horns (just clicking of relay). soaked and roughed them up also with no change in success

4) Checked the fuse. (Good)

5) Pulled relay and tested with a continutanty meter. Had it through the contacts between the horn switch in the steering wheel and the contact for the fuse box wire.

6) Tested all horns with battery charger with negative onto the mounting bracket and positive on terminal. (Nothing out of any horn, even after abusing them a bit more with the rubber mallet)

7) Went out and bought a new horn, tested it at the part store, installed on truck with ground wire between body and new horn and still only get a clicking of the relay.

At that point I gave up and had to get back to work as I was already 30 min late for lunch hr.

Tonight I am going to run a wire from the negative side of the battery to the mounting stud of the new horn to by pass any grounding issues to see if it works.

Does anyone have any other ideas as to what to try. I have been cussing on this and usualy that would be bleeped out by a horn noise but, well you know that situation.

With these old trucks, sometimes the connections are corroded just enough to not let all the power through, yet still show voltage on a meter.

Right now, that's all I got.

Digz, that's the starter solenoid and ballast resistor.

Blackace, step 2 is proving the horns are inop. Start with a known-good horn. It MUST pass Step 2. Do this FIRST!!!
Then, take a test light and connect it to a GOOD ground. Touch it to the relay. There should be one wire that has power at all times. This is the feed wire. It must have power! Next is the trigger side. This seems to be proven by the clicking noise. We will assume that the horn button and wiring for the trigger side is all good. Now touch the test light to the output wire to the horns at the relay. Press the horn button and make sure the relay is supplying power from the feed wire to the output wire. This MUST work!
Now, take the test light and go to the wire under the nose that connects to the horn. Again, it must have a good ground. Repeat the output test with the test light grounded and the tip on the horn wire. It must light up when the button is pressed. If you have power here, it's gotta be the horn ground. Sand down the spot where it's mounted.


BTW, from the info provided, my guess is the output wire is broken somewhere or the relay trigger side is good, but the contacts or connections are bad. That's why a test light is a good way to quickly test the output side.

Thanks Rod. I had done most of this with not much success and I have just purchased a new horn so have that covered now. Does the relay need to be mounted (aka grounded also) in order for it to work properly. Also is it possible for the relay to click and not push power throught it. I have made the assumption that the clicking meant the relay was working.

Relay body grounded - it MAY need a good ground. Some of the older non-Bosch style did ground through the body for the trigger. I would clean and tighten it as a matter of course. However, since it DOES click, that sort of proves the trigger side. If it has 4 terminals, it's grounded through one wire. If it only has 3 terminals, it's grounded through the body of the relay.



Click without working - Yes, it can 'trigger' but not complete the feed circuit. This can be due to the contacts inside or even a loose wire from the contacts to the power feed or output terminals.
Here's a basic wiring diagram
http://www.steveshood.com/images/horn_wiring.jpg
Here's a description of a relay (Bosch style)
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

Thanks Rod. I do have the 3 post relay. Most of my testing yesterday was with it plugged in to the harness but I did not mount it back up under the dash as I was going in and out of truck testing different things. Might have hexed myself on that one. I did plot out the wiring diagram the night before. it is a very simple system, aka why it is so frustrating to not get it figured out much quicker. I will grind the area around where the horns mount to ensure a good ground, check with the test light per your instructions, and I was able to get one of the horns to start working. That abusing it seems to of helped so will now have 2 known working horns to test with. Will get pics and keep you updated how the weekend goes.

Boola, boola HEX!
Yes, it sounds like you started chasing your tail on that one!

One other thing I hesitate mentioning, but if you are careful and understand what you are doing (and don't jump when the horn blares) is to connect everything up properly, and using a jumper wire, connect the feed terminal to the
output terminal at the relay. You will probably get a spark. If the wiring horn and ground are good, you will get a horn! That proves the feed, output, horn and ground, leaving the relay and trigger circuit. Shorting across stuff is not as safe as fully checking each part of the circuit, but can shorten diagnostic time IF you are careful and understand what you are connecting!

Did I put in "CAREFUL" enough?
The reason being is that someone who doesn't know the difference between open and short can easily start an electrical fire which is a BAD thing.

Yea Rod that is usually a bad thing, especially when I am not real graceful getting out of the truck after laying on my back on the floor. Would not be pretty.

I will keep that as a last resort. I have a few different things to try over the weekend. Ground the horn at the front of the truck from the neg from battery. (Check ground of system)
Test power on the output terminal to see if the relay is putting power through it when tripped.
If all is good so far, then test out at horn and see if power is getting there.

Thanks for the help. and yea you did say careful a few times there.

Yep I knew the one was the ballast, the other just looked to cheezy for a starter sol. then i remembered how it grounded. I took a bunch of pics when I dismantled the 66 just for reference stuff. of course I didnt label them ,,lol

Well, they aren't the big honkin' solenoid that Ford uses (and most racers do too), but it's better than the Chevy on the starter deal.
They also fail only rarely. I can't think of more than one or two I ever had to replace, compared to 30 or so Fords, and Chevy starters? Don't even go there!
Mopars do have the ballast and the EI boxes that do go out.
Ford's first EI boxes were embarrasing until the aftermarket figured out how to build them. The TFI was another mess, and GM 2.8 V6 EI dist. had issues. No one is perfect.

UPDATE:: After more PB Blaster, and a bigger rubber mallet, was able to get a set of horns working. Got them tuned up and mounted on the truck. What a sound heck I was honking it all the way home from work. Is the loudest set of horns on any of the 7 vehicles in the stable. thanks everyone for all the help, and Rod you were correct, in that the horn relay needed to be mounted to ground out the system. Nothing like that sound of the old hi/low tone horns

Yahoo! Give that man a Star!